室外氣象站與 溫室溫控 方 煒 台大生機系教授 也是室內感測元件 風向計 風速計 光度計 溫、濕度計 雨感器 室外氣象站七大感測元件 雨量計 雨感器相關之控制策略 • 偵測下雨後的動作 – 關閉天窗，避免飄雨進入溫室 – 打開室外的遮蔭網，允許落雨來 刷洗溫室屋頂 風速計相關之控制策略 • 當室外風速高於某設定值時的動作 – 關閉室外的遮蔭網，避免被強風吹壞.
Download ReportTranscript 室外氣象站與 溫室溫控 方 煒 台大生機系教授 也是室內感測元件 風向計 風速計 光度計 溫、濕度計 雨感器 室外氣象站七大感測元件 雨量計 雨感器相關之控制策略 • 偵測下雨後的動作 – 關閉天窗，避免飄雨進入溫室 – 打開室外的遮蔭網，允許落雨來 刷洗溫室屋頂 風速計相關之控制策略 • 當室外風速高於某設定值時的動作 – 關閉室外的遮蔭網，避免被強風吹壞.
Slide 1
室外氣象站與
溫室溫控
方 煒
台大生機系教授
Slide 2
也是室內感測元件
風向計
風速計
光度計
溫、濕度計
雨感器
室外氣象站七大感測元件
雨量計
Slide 3
雨感器相關之控制策略
• 偵測下雨後的動作
– 關閉天窗，避免飄雨進入溫室
– 打開室外的遮蔭網，允許落雨來
刷洗溫室屋頂
Slide 4
風速計相關之控制策略
• 當室外風速高於某設定值時的動作
– 關閉室外的遮蔭網，避免被強風吹壞
Slide 5
風向計相關之控制策略
• 南北座向溫室，溫室屋頂有東西兩側
天窗，可分別控制且溫室有側窗
• 偵測到風由西、西北、西南方來臨時，
自然通風模式下可打開東側的天窗、
關閉西側天窗與打開西側側窗
• 偵測到風由東、東北、東南方來臨時，
自然通風模式下可打開西側的天窗、
關閉東側天窗與打開東側側窗
Slide 6
朝東/西面開口分別為天窗1/2
兩者可分別控制
Slide 7
溫、濕度計相關之控制策略
•
自然通風溫室
–
溫升或濕度過高時
1. 開天窗
2. 開側窗
–
溫降或濕度過低時
1. 關側窗
2. 關天窗
• 自然/強制通風溫室
–
溫升或濕度過高時
1. 開天窗
2. 開側窗
3. 關天窗,風扇啟動
溫降或濕度過低時
1. 關風扇，開天窗
2. 關側窗
3. 關天窗
風扇啟動時天窗與側窗關閉
風扇啟動時也可分階段，有時
搭配水牆啟動
Slide 8
濕度的相關參數設定
濕度的相關參數設定
Slide 9
天窗控制溼度
Slide 10
光度計相關控制策略
• 室外光量
– 控制室外遮蔭網開啟與關閉
– 控制室內遮蔭網開啟與關閉
• 室內累積光量
– 允許計算作物累積生長狀況
– 做為灌溉控制的依據
Slide 11
溫室內外PAR與累積日總PAR
Slide 12
溫、濕度複合控制策略
室內濕度過高，調降室內溫度控制設定值來提早換氣
室內濕度過低，調高室內溫度控制設定值來延緩換氣
Slide 13
由溫室內溫溼度計算蒸氣壓差
Slide 14
複合環控 (溫度與溼度)
Slide 15
溫度、光量複合控制策略
• 室內溫度未達高溫範圍
–允許提高光量設定值
• 室內溫度已達高溫範圍
–允許降低光量設定值
• 加溫模式
–白天：打開所有遮蔭網（不遮蔭）
–夜間：關閉所有遮蔭網與保溫膜
Slide 16
遮蔭網設定
晨間溫度較低允許較高光量
4
3
2
1
4
Slide 17
溫室溫控與相關英文
方煒 (台大生機系)
Dr. McMahon (園藝與作物科學系，Ohio 州立大學)
Slide 18
溫室溫控的目的在調節溫室內
作物生長與分化
Controlling Greenhouse
Temperatures to Manipulate
Greenhouse Crop Growth and
Development
Slide 19
Controlling greenhouse temperatures
involves moving heat into or out of a
greenhouse.控制溫室的溫度涉及將
熱量搬進與搬出溫室
Really though, we are talking about
moving heat into or out of a plant to
manipulate how it grows and
develops. 仔細想想，其實是涉及將
熱量搬進與搬出作物來調控其生長
與分化
Slide 20
First, a quick reminder about the differences between growth and development.
首先複習一下生長與分化的差異
Growth is an irreversible increase in mass (dry weight).生長指質量增加的不可
逆過程，Development is a sequential movement through life stages. 分化則
是指生命發展經歷的階段
Which plant (both are the same age) has the most growth, the most
development? 這兩株作物栽培了同樣長的時間，哪一株有最大
的生長，哪一株有最大的分化？We use temperature to
manipulate both growth and development.我們使用溫度來調控兩
者造成差異.
Slide 21
Moving or Transfering Heat
熱量的搬移或輸送
•
•
•
•
Conduction傳導
Convection對流
Thermal Radiation輻射
Evaporation蒸發
Slide 22
Conduction傳導
• Direct transfer of heat熱
量的直接傳遞
• Kinetic energy transferred
due to collisions由於分子
碰撞造成動能傳遞
• Billiard balls撞球
• Boiling water on electric
stove電爐上的熱水
Slide 23
Convection對流
• Air or fluid moves to new location to transfer heat
空氣或液體移動到新的位置來傳輸熱量
• Chimney effect 煙囪效應 (Passive ventilation自
然通風)
– Hot air rises, cold air sinks 熱空氣上升，冷空氣下降
• Convection oven 對流烤爐
• Forced air heating and air conditioning熱風加熱
與冷凍空調
Slide 24
Radiation輻射
• Heat energy released as
Electromagnetic Radiation
(EMR)熱能以電磁波方式輻射
• Everything above absolute zero
emits electromagnetic radiation
任何物體溫度在絕對零度以
上都會輻射電磁波
• Wein’s law煒恩定律
– As temperature , energy
emitted as shorter 溫度月高
的物體輻射出來的波長越短
• Plant loses most of heat this
way 作物多以此種方式損失熱
量
• Some greenhouses use radiant
heating systems有些溫室內使
用輻射加熱系統
Slide 25
Evaporation蒸發
• Heat transfer associated with phase change (liquid
to gas)熱量傳遞與相變(液態變氣態)相關
• Latent heat of vaporization蒸發潛熱
– Water 水 = 540 cal/mL; 1,064 Btu/lb
– High compared to other liquids液體中是蠻大的
• Plant cools itself by evaporating water from
stomates作物透過氣孔蒸發水分來散熱
• Evaporative cooling pads help cool some
greenhouses某些溫室透過蒸發冷卻水牆來協助
降溫
Slide 26
Energy Budget of Greenhouse溫室內能源的
收支 =Gains minus Losses進入的- 出去的
Heat Gains獲得的熱 Heat Losses損失的熱
• Solar radiation and
‘trapped’ heat太陽輻
射與出不去的熱
• Heating system加熱
系統
• Other machines機械
設備
– Fan motors風扇馬達
– Lamps/ballasts燈具/
安定器
• Conduction傳導
– Direct transfer of heat through
glazing material
Air layer in glazing reduces
conduction loses熱量可透過被覆材
料傳遞，雙層被覆材料之間的空氣
層有助於減少熱傳導
• Ventilation/Infiltration通風/滲漏
– Loss of heat and openings.熱量與開
口的損失
– Can be deliberate (summer cooling)
可以是經過精密計算的(夏季通風
降溫)or unwanted不要的 (drafts)賊
風
Slide 27
Greenhouse Effect 溫室效應
An unventilated greenhouse heats up from solar radiation because light
enters the greenhouse and much of what is not absorbed by the plants for
photosynthesis is absorbed or reflected back by plants and other objects.一間
不通風的溫室會被太陽輻射加熱，因為進來的光線大多未被作物吸收用
於光合作用或者被作物和其他物體反射
Slide 28
Greenhouse Effect 溫室效應
The absorbed light can be reemitted as heat radiation.
Most greenhouse glazing
materials are opaque (meaning
they don’t transmit) heat
radiation. This means that
energy is trapped and the
greenhouse heats up, often to
very high and life threatening
levels.被吸收的光線可以再
以熱輻射方式傳出. 但是大
多數溫室被覆資材對熱輻射
而言，都是不透明的；換言
之，熱量被限制在溫室內造
成溫室可能升溫到危害作物
的情況
Slide 29
Greenhouse Effect 溫室效應
The problem can occur at any season. In the
winter it occurs on very cold bright, sunny
days when the vents cannot be opened.這問
題可能發生在任何季節. 冬季發生在很冷
卻晴朗的日子當通風口完全未打開
Slide 30
Greenhouse effect 溫室效應
• Increased CO2 and other gas
levels in atmosphere大氣層中
二氧化碳與其他溫室氣體含
量提高
• Absorb sun’s energy and trap
the energy in the atmosphere,
much like glass greenhouse
traps sun’s heat inside溫室氣體
吸收了太陽能並將能量侷限
於大氣層中，就像玻璃溫室
限制熱量出去
• Gives greenhouse a ‘bad rap’溫
室被污名化
Slide 31
Energy Budget of a Plant
作物的能量收支
• Gains獲得
– Solar radiation太陽輻射
– Thermal radiation熱輻射
(from radiant heaters由輻
射加熱器獲得)
– Convection from warm air
與暖空氣的對流
• Losses損失
– Radiation輻射
– Transpiration*蒸散
– Convection to cool air與
冷空氣的對流
* Transpiration is the primary way in which a plant loses
energy, it is its primary cooling mechanism. That’s why
keeping plants well-watered on hot days is so important.蒸散
是作物散熱的主要途徑，這是作物主要的降溫機制。也
是為什麼在熱天讓植物有良好的灌溉是那麼重要。
Slide 32
Determining Greenhouse Heat Requirements
溫室加熱需求的計算
• Calculate heat loss from g-house計算溫室的熱損失
Q = [(A1* x U1) + (A2* x U2)] x (T -T ) x W x C
Inside
Outside
– A = Surface Area of exposed walls 溫室各屋頂與牆面表面積- calculated
by grower業者計算
– U = Conductance factor 傳導係數- provided by manufacturer廠商提供
– Ti – T0 = Temperature Differential 溫度差 - calculated from climate data由氣
象資料瞭解
– W = Wind Factor 風速因子- calculated from climate data由氣象資料計算
– C = Construction Factor 結構因子- provided by manufacturer廠商提供
• Q is how much heat a heating system must be able to supply.Q
是加熱系統所需提供的加溫需求
* The subscript indicates different wall/glazing materials, e.g. wood, glass, concrete, plastics, etc.)
Slide 33
You ALWAYS consider the:永遠需要考慮紀錄
中存在的
Coldest temperature recorded最低溫度
Hottest temperature recorded最高溫度
Greatest snowfall recorded最大降雪量
Highest wind recorded最大風速
Why???
Slide 34
RB
G
L
H
W
Surface Area = 2(L x H) + 2(W x H) + 2(L x RB) + (G x W)
What’s so important about knowing surface area when we’re
talking about heating and cooling a greenhouse???當我們在談
溫室的加熱或降溫，為什麼溫室的表面積這麼重要？
Slide 35
Heating Systems加熱系統
• Localized Heating局部加熱
– Heater per section
– Unit heater or forced-air heater
– Radiant heater
• Central heating中央加熱
– Heat created in central location and moved throughout
greenhouse
– Perimeter heating
– Floor heating
– Bench heating
• Solar heating system太陽能加熱
Slide 36
Unit heaters單元加熱機
• Combust fuel to heat air
which is moved by fan
(convection)使用燃油來加
熱空氣並透過風扇送風
• Efficient for heating small
spaces小空間加熱有效率
– (2000-6000 ft2)(200-600m2)
– Polyhouses塑膠布溫室
• 175,000 Btu/hr
• e.g. Reznor (as in Trent Reznor of
Nine Inch Nails), Modine
Slide 37
Air Distribution空氣輸送
Horizontal airflow (HAF)
fans
Convection tube from
forced air heater.
Slide 38
Typical HAF fan placement
室內均風風扇的典型安置方法
• At eave height, pointing straight ahead, 50’ apart在屋簷高
度、朝前、50呎距離
• Arrange so that air moves in a circular pattern through
house or section讓空氣在溫室內或該區域內造成環場的
效果
• Air speed = 50-100 fpm空氣流速
– Leaves slightly moving葉片輕微擺動
• Smallest fan possible風扇愈小越好
– Less electricity耗電小
– Less shading遮蔭小
• First fan in row各列的第一個風扇
– 10-15’ from wall 距離牆面10~15英呎
– Could be unit heater可以是單元加熱器
• Important for many reasons很重要基於多重原因
Slide 39
HAF’s Over Bedding Plants
安裝於花壇作物上方
Slide 40
Radiant Heating輻射加熱
• Iron pipe running length of greenhouse鐵管沿溫室走向安
裝
– One end一端– burner (nat. gas or methane)燃燒爐(天然氣或丙烷)
– Far end of pipe遠端 – exhaust (outside)室外排氣
• As pipe heats up, radiates infrared 鐵管被加熱就能輻射
能量
– 900°F = 3800nm
• Anything containing water (e.g. plants) absorbs this energy
任何含有水分的物體(譬如作物)都能吸收此輻射熱能
• Aluminum reflector to aim radiation at plants使用鋁製反
射片來讓輻射管路對準作物
Slide 41
Advantages of Radiant Heating
輻射加熱的優點
• Fuel bill reduction燃料成本降低
– Less heat lost in exhaust較少熱量損失
– Cooler air temp in greenhouse溫室內空氣溫度
較低
Disadvantage缺點
• Most temperature control systems measure air
temperature to adjust temperatures. With radiant heaters,
actual plant/leaf temperature should be measured.大多數溫
度控制系統靠量測空氣溫度來做控制，使用輻射加熱需
要能夠量測作物/葉片溫度
Slide 42
InfraRed Heaters
紅外線加熱器
Slide 43
Central Heating中央加熱
• Centralized boiler burns fuel中央鍋爐
– Larger variety of fuels可以使用多種燃料
• Boiler heats water to: 鍋爐把水加熱
– Hot water (180°F – US)熱水(82 oC)
– Steam (215°F)蒸氣(101 oC)
• Move hot water or steam around greenhouse with
pipes and release heat將熱水或蒸汽在溫室內透
過管路輸送來傳遞熱量
Slide 44
*Hot water* vs. Steam
• 1 Btu/lb of water as
temp 1°F
• Circulating pumps
• To get more heat:
– Pressurize system
– Stack pipes
– Finned pipes ( SA)
• Heating more uniform
throughout greenhouse
• Steam water 970 Btu/lb
+ 1 Btu/lb as temp 1°F
• Moves on its own
• More expensive to operate
• Less pipe needed but
stronger fittings
• Safety concerns
Slide 45
Distribution of Central Heat
• Heating pipes under bench
• Overhead pipes
• HAF fans circulate air
Slide 46
Floor Heating地底加熱
• Most sense with floor
production
• Can only use hot water
– Steam too hot
• Plastic tubing in
concrete floor
• Heat supplied where
plants are located
• Floor dries faster after
getting wet.
Slide 47
Floor Heating Systems
Floor heating units and
pipes in a foliage house.
Floor heating unit in a
bedding plant house.
Slide 48
Bench Heating植床上底部加熱
• Bottom heat
• Plastic tubes with hot
water directly on
bench
• e.g. BiothermTM
• Single hot water
heater usually
sufficient
• Propagation
Slide 49
‘Bottom’ Heat for Benches used
for propagation and/or growing
Slide 50
Fuel Comparison (Hot water)
熱水系統的燃料比較
Fuel
Cost
Efficiency
(Btu/$)
Delivery
Bituminous
Coal
$41/ton
639,000
Hard to store,
shoveling?
#2 fuel oil
$0.84/gal
126,000
Buried tank
Natural gas*
$4.69/
1000ft3
229,000
Pipeline
Slide 51
Combustion Concerns 燃燒相關
• Vent heater exhaust to outside of greenhouse
– Ethylene (C2H4) generation from incomplete
combustion.
– Other unwanted products from incomplete
combustion (CO, sulfur compounds, etc.)
– Avoid re-entry of exhaust through ventilation
Slide 52
Solar Heating太陽能加熱
• Collect energy from sun and use for heating
– Store as hot water or rock
• Back-up heating system
• Expensive and to date not very efficient
Slide 53
Comparison of heating systems
加熱系統比較
Heating
system
Installation
costs
Fuel Used
Heat Transferred
to Plants
Unit
heaters
Radiant
heater
Central
heating
$0.501.00/ft2
$1.502.25/ft2
$2.503.25/ft2
N.g., P, K,
#2 oil
N.g., M
Convection
Wood, oil,
coal, N.g.
Convection
Solar
heating
$8-10/ft2
Sun
Convection/
Radiation
Radiation
Slide 54
Heat Conservation 節能的方法
• Reduced Surface Area to Volume
(SA/V)降低溫室總表面積對總
體積的比例
– Multiridged greenhouse連棟
• Double-layer glazing雙層被覆
• Thermal screen節能保溫膜
– Shade or black cloth
• Wall insulation牆壁隔熱
• Windbreaks 溫室外設立風阻
• Cool temperature crops選擇低溫
作物
Slide 55
Cooling and Ventilation
Slide 56
Why Ventilate? 為什麼要通風
1.
Reduce air temperature
降低空氣溫度
2.
Replenish補充CO2
Outside ~380 ppm, inside
can be much lower
3.
Reduce relative
humidity降低相對濕度
Condensation on leaves
Disease減少葉片的水
分凝結就能降低發生疾
病機率
Slide 57
Natural/Passive Ventilation
自然/被動通風
• Chimney effect – convection 煙囪效應 – 對流
– Buoyancy浮力
• Warm, less dense air rises暖空氣較輕，上升
• Cooler, more dense air sinks冷空氣較重，下降
• N-S orientation uses
prevailing west winds 南
北向可利用西向風
Slide 58
The effectiveness of passive ventilation is most
effective when side vents can be opened to increase
airflow out the top vent 最有效的自然通風是側窗
與上方開口都能打開
Slide 59
Staged Vents 分階段的開口
• As temp ↑, 溫升
– Open ridge vents先開上方開口
– Open side vents再開側窗
• As temp , 溫降
– Close side vents先關側窗
– Close ridge vents再關上方開口
• Manual or automated control
(connect to thermostat) and
program to open/close vents in
proper sequence. 手動或自動控
制都需要依照正確順序
Slide 60
Side Vents 側邊通風口
Slide 61
Advanced Passive Ventilation
先進的自然通風
With advent of plastics and
better engineering, able to
passive ventilation to
adequate levels
Slide 62
Vents can provide an entry for insects. 屋頂開口可能
有昆蟲進入Screening can be used to exclude insects.
防蟲網可以使用
Slide 63
In contrast to passive ventilation, many
greenhouses rely on mechanical (fan or
forced) ventilation system.
除了自然通風的溫室之外，許多溫室
仰賴強制通風
Slide 64
Mechanical or Fan or forced
Ventilation 機械(強制)通風
• Exhaust or ventilator fans
supplement natural ventilation
• Locate on side opposite
prevailing winds安裝於迎風
面對側
– Pull air through ghse.
• Exchange all air in greenhouse
once per minute維持每分鐘換
氣一次
• Distance from inlet to exhaust
no more than 150’空氣進出口
距離不超過45.7m.
Slide 65
Determining Cooling Requirement
降溫需求的決定
• 1 complete air exchange per minute每分鐘一個溫
室體積的空氣交換量
• Volume of greenhouse = volume of air to be
moved溫室體積=風扇必須搬運的空氣量
• Fan capacity = amount of air each fan moves風扇
能力=風扇可以搬運的空氣量
– Measured in cfm (cubic feet per min)以cfm為單位或
m3/s或m3/min
• Better to have two smaller fans than one big fan
兩個小風扇比一個大風扇好
– More uniform cooling降溫更均勻
– No more than 25’ apart相隔不超過7.6m
Slide 66
RB
G
L
H
W
L x W x H + (L x W x G)/2 = Volume
Why is volume important when designing cooling systems?
當要計算溫室降溫通風時，為什麼溫室體積的計算很重要
Slide 67
Fan Ventilation Stages
強制通風的控制分段
•
•
If fan running, ridge vent
closed風扇啟動時天窗與
側窗關閉
As temp ,溫升
1.
2.
3.
Open ridge vents開天窗
Open side vents開側窗
Close ridge, fans on關天窗與
側窗，開風扇
As temp ,溫降
1.
2.
3.
Fans off, open ridge關風扇，
開天窗
Close side vents關側窗
Close ridge vent關天窗
Slide 68
Fan Components風機組成
Louvers – “blinds” for fan 百葉
Closed while fan not in use風扇不用時關閉
In line with g-house wall與牆面對齊
Keep wind and rain out擋風與擋雨
Screen鐵網
Outside of fan安裝於風扇外
Mesh opening網目開口 1 in2
Safety reasons安全理由
Slide 69
Evaporative Cooling Pads
蒸發冷卻水簾片
Corrugated cellulose pad
located on opposite wall from
ventilator fans (windward
side)
• Water flows over and through
the cooling pad
• Fans pull warm outside air
through cooling pad
• Water absorbs heat from the
air as it evaporates which
cools the air as it enters the
greenhouse
540 cal/g of water!
That’s a lot of cooling
capability
Slide 70
Pad & Fan Specifications
•
•
•
•
•
Pad & fan systems work best when RH low
Optimal pad to fan distance = 100-150’
1 ft2 pad for 150 ft3 air per min
Correct for elevation and distance
Typically 4 or 8” thick 一般10或20公分厚
Slide 71
More on Cooling Pads
• Water distributed at top of the pad
– ½ gal per min per linear foot
– Recycled in sump tank
• Algae problems?長藻的問題
– Disinfectant in circulating water
• Small insects (e.g. thrips) sucked in小昆蟲
(譬如薊馬)被吸入
– Treat water with insecticide以殺蟲劑處理用水
Slide 72
Swamp or Package Coolers
單元式冷風機
• Evaporative coolers for small greenhouses小
溫室使用蒸發冷卻的冷風機
– Hobby greenhouse, small rooms
– Air drawn in by fan across cooling pads
• Cool air “pushed” into greenhouse冷空氣被
吹入溫室
Slide 73
Fog Cooling Systems
• Fog is created in the greenhouse在溫室內
造霧
– Water forced through small nozzles at high
pressure (~1000 psi)高壓噴霧產生小霧滴
• As fog evaporates, takes heat out of air
• Cannot use hard water, clogs nozzles不能使
用硬水，會使噴嘴阻塞
• Humidistat → 80-90% RH
Slide 74
Shading as Cooling Mechanism
以遮蔭來降溫
• Reduce light intensity and
reduce temperature透過降
低入射光量來降溫
– Shade Cloth遮蔭網
– Shading Compound塗料
• Adjust light intensity for
high quality crops調整光
量種出高品質作物
Slide 75
Shading as Cooling Mechanism
• Shade Cloth遮蔭網
– Can be applied and
removed as needed收放自
如
– Can be mechanized or
under computer control可
機械化與電腦化控制
– Does not reduce the radiant
energy (heat load) entering
the greenhouse安裝於室內
則無法減少進入的能量
Slide 76
Shading as Cooling Mechanism
• Shading Compound遮蔭塗料
– Cannot be removed and applied as
needed無法收放自如
– Must be manually removed in fall
在秋季必須人工清除
– Have to use specially formulated
shading compound有特殊配方
– Does reduce radiant heat load in
the greenhouse可減少進入溫室的
熱負荷
Slide 77
Winter Cooling Systems冬季降溫
• Passive ventilation被動通風
– Open ridge vents開天窗
– Have to be sure they do not
freeze open!確認不會被凍住
• Active cooling 主動降溫
– Convection tube通風管
• Bring in cool outside air or
circulate cooler air from ridge
area引入室外冷空氣會做內循
環
– HAF fan systems
• Draw cool air down from ridge
area由屋脊拉下較冷空氣
On bright, sunny subzero winter days, unvented greenhouses
can have temps well over 100F (37oC). Bad for plants and
workers.
Slide 78
Measuring Temperature溫度的量測
• Place sensors as close to plants
as possible and not in direct sun
• Aspirated thermostat 通風的溫
度計
– Fan blows air across thermometer
– Prevents ‘dead air’ space from
developing around the sensor
– Gives more accurate reading of
temperature
– Within 2-3° of real temp rather
than 4-5° with non-aspirated unit
Slide 79
室內溫、濕度感測器
Slide 80
Using temperature to
control plant growth.
使用溫度控制作物生長
Slide 81
Temperatures in Greenhouse
溫室內的溫度
• Air temperature空氣溫度
– Most commonly and easily measured最容易量測
– Night temp easier to control than day夜間溫度比白天
容易控制
• Leaf temperature葉片溫度
– Difficult to measure不容易量測
– Most likely different from air temp與空氣溫度多半不
同
• Media temperature介質溫度
– Roots根系
– Propagation種苗繁殖
Slide 82
How Temperature Affects Plants
溫度如何影響作物
• Flower induction in some species誘導開花
– e.g. Easter lily、Phalaenopsis 百合、蝴蝶蘭
• Interacts with photoperiod to control floral induction
與光週期合併來控制開花
– Heat delay
• Bud dormancy or vernalization花苞休眠或春化
– e.g. hydrangea & azalea繡球花與杜鵑
• Controls rate of stem elongation控制莖生長長度
– *Most important最重要
Slide 83
Adverse Effects of Temperature
溫度的不利影響
• Chilling injury often occurs at less than 50°F/10°C
–
–
–
–
–
–
–
African violets
Poinsettias聖誕紅
Hibiscus木槿
Gloxinia大岩桐
Tomatoes蕃茄
Foliage plants觀葉植物
Phalaenopsis蝴蝶蘭
• Chilling injury - membrane dysfunction膜功能障礙
Lipids in tropical and subtropical plant membranes solidify
Slide 84
Growth vs. Development
• Growth生長
– Increase in size
(volume or weight) of
plant or organ that is
irreversible and
permanent
• Development分化
– Aging process of the
plant – phases that
plant goes through as
gets older
•
•
•
•
•
Germination
Vegetative growth
Flowering
Fruit set
Seed release
Slide 85
Growth Rates of Plants
作物的生長速率
• Growth rate = The speed at which an organ
goes through a certain developmental stage
– Stem growth
– Flower production
– Leaf unfolding
• All growth processes have different
temperature response curves所有的生長過程
都有不同的溫度反應曲線
– Even within species即使是相同品種
– Cultivar specific依品系而定
Slide 86
Optimal Temperature最適溫度
• Every species has both optimal and tolerable temperature
range for growth各品種都有最適與可容忍的溫度範圍
• Optimal range: produce high quality plants most rapidly
最適範圍:可最快長成最高品質
– Mums = 61-64°F (night)菊花:16~17oC夜溫
• Tolerable range: still grow but more time and lower
quality可容忍範圍:仍可生長但是既慢且低品質
– Mums = 40-60°F & 65-80°F (night)
Slide 87
Cumulative Growth累積生長
• Instantaneous plant temperature controls growth at
any moment各瞬時的作物溫度控制當時的作物生
長
• Cumulative growth in 24 hr = average of individual
growth rates during that period累積24小時的作物生
長代表在該時段內作物的平均生長狀況
• Manipulating average daily temperature in the
greenhouse (within tolerable range) will change the
rate of plant development調控溫室內的日總平均溫
度可以改變作物分化速率
– Fast growth high quality growth長得快不代表高品質
Slide 88
Average Daily Temperature
日總溫度平均值
Greenhouse growers have target temps for day
and night溫室業者有設定的日溫與夜溫
Can calculate an average daily temp.
Weighted average加權平均
– Day 16 hr @ 77°F日間16小時，平均溫度77°F
– Night 8 hr @ 68°F夜間8小時，平均溫度68°F
– Weighted Avg. temp加權平均溫度
= [(16x77)+(8x68)]/24 = 74°F
Slide 89
Growth Curve生長曲線
Maximum
Maximum is
usually not
optimum.
最大通常不代表
最佳
Optimum is the
temp. that has
the plant at the
stage you want it
to be at!!!!!!
最佳溫度決定於
你希望作物的生
長速率是多少
Slide 90
Growth Curve
• Linear Range: portion of curve that is a
straight line線性範圍
• Base temperature: intersection of the straight
line (linear range) and the X-axis (X-intercept)
基礎溫度
• Maximum temperature: peak of growth rate
curve最大溫度
Slide 91
Degree-day Concept
度日數的觀念
• Slope: Dy/Dx Change in growth rate / change in temp
• e.g.# leaves/day/°F → leaf unfolding
• e.g. inches/day/°F → stem elongation
• Daily increase in leaf production or stem
elongation as you raise the average temp 1°F平
均溫度增加1°F，葉片生長或莖長的每天增加
量
Slide 92
Degree-day Concept
• The amount of heat (or degree-days) above the
base temp that must accumulate for a
developmental event to occur在基礎溫度以上累
積的熱量都用來提供作物生長發育所需
• 1 degree-day will accumulate when the day’s
average temp is 1°F above base temp
– Average temp = 55°F
– Base temp = 50°F
– 5 degree-days will accumulate that day
Slide 93
Degree-day Concept
• Degree-day constant associated with every
development stage 度日數與每個分化階段都相關
– e.g. 80 degree-days needed to reach a certain stage
• All of the following would accumulate 80 degreedays以下的幾項都可得到累積的80度日數
– 80 days @ 1° above base temp
– 40 days @ 2° above base temp
– 8 days @ 10° above base temp
• Allows crop growers to schedule and time crop
development允許作物栽培者可以用來針對作物的
生長分化進行規劃與排程
Slide 94
Application of Degree-days度日數的應用
(hypothetical numbers使用假設的數字)
• Easter Lily production during leaf development
– Slope = 0.02 leaves/degree-day
– Degree-day constant = 1/0.02 ≈50
• 50 degree-days/leaf
– What temp to produce 3 leaves in 10 days?
– Avg daily temp = total degree-days + Tbase*
desired time
* Tbase = base temperature
Slide 95
Example cont’d
• What avg. daily temp to produce 3 Easter lily
leaves in 10 days?
– Base temp = 55°F
• Avg temp = 3 x 50 + 55
≈ 70F
10
Maintain 70F avg. temp and you should have 3
new leaves in 10 days!
Slide 96
• Most E. Lily growers use a ‘bud meter’ once flower
buds are visible.百合業者使用花苞長度量尺
By measuring the
length of the bud, the
grower knows how
warm to keep the
greenhouse to get the
bud to the selling stage
by Easter. The bud
meter is based on
degree days.
量測花苞的長度，業者可以瞭解溫室溫度需
設定多少度才能趕上復活節銷售旺季。此
花苞量尺的設計就是依據度日數。
Slide 97
Original Applications of Degree-days
度日數的早期應用
• Field-grown crops田間栽培作物
– Count degree-days by measuring temp由量測溫度來計算
度日數
– Predict days to harvest預測收穫時間
• Apples蘋果: bloom開花 → harvest收穫 = 2800 degree-days
– Predict insect hatching/molting 預測昆蟲孵化/蛻皮
• Degree-days = (Tmax – Tmin)/2 – Tbase
• Prediction only - growers of field-grown crops have
no control over temperature 只能預測-因為田間溫
度無法控制
Slide 98
Temperature and
Growth (stem height) Regulation
溫度與株高調控
Slide 99
History of DIF
• Originally discovered in 1944
• “Rediscovered” and developed as a growth
regulation technique生長調節技術 in late 1980’s
by Dr. Royal Heins at MSU
• The DIFference between day and night
temperature in a greenhouse will affect internode
elongation and consequently, stem length.溫室內
日溫與夜溫的差會影響節間長度，影響莖高
Slide 100
DIF
DIF = Day temp日溫– Night temp夜溫
+ DIF when Day temp> Night temp
0 DIF when Day temp = Night temp
- DIF when Day temp < Night temp
Slide 101
DIF effects on internode elongation:
Within normal growing temperatures,
the more positive the DIF, the longer
the internodes.在正常生長狀況下，
DIF值正的越多，節間長度越長
Slide 102
Greenhouse
A
B
C
Day temp
60°F
55°F
50°F
Night temp
50°F
55°F
60°F
Avg. Daily
temp
DIF
55°F
55°F
55°F
+10
0
-10
Internode
length (plant
height)
Tall
Medium
Short
Slide 103
Effect of DIF on Stem Elongation
Slide 104
DIF Responding Species
受DIF影響的品種
•
•
•
•
•
•
•
•
•
Easter lilies百合
Poinsettias聖誕紅
Snapdragon金魚藻
Rose玫瑰
Petunia牽牛花
Carnation康乃馨
Impatiens鳳仙花
Tomato蕃茄
Pepper小黃瓜
DO NOT RESPOND
• Hyancith風信子
• Tulip鬱金香
• Narcissus水仙
• Squash南瓜
Slide 105
Degree-days vs. DIF
• Avg. daily temp (or degree-day accumulation)
control rate of plant development日總平均溫度
或者總度日數控制作物的生長速率
• DIF responsible only for plant height regulation
(internode elongation)DIF只用來調節作物的生
長高度(節間長度)
– More positive DIF → the taller the plant長得高
– More negative DIF → the shorter the plant長得矮
Slide 106
Greenhouse
A
B
C
Day temp
60°F
55°F
50°F
Night temp
50°F
55°F
60°F
Avg. Daily
temp
DIF
Internode
length (plant
height)
55°F
55°F
55°F
+10
Tall
0
Medium
-10
Short
Which greenhouse would have the tallest plants? The
shortest? The furthest along in development?
Slide 107
Side Effects 副作用
of Extreme極端的–DIF
• Chlorosis缺綠病;變色病 (esp.
DIF < -10F)
– Bedding plants (e.g. salvia)
• Leaf orientation 葉片走向
– Problem on Easter Lily
– (photos courtesy of Dr. Harold
Wilkins)
Slide 108
Other effects 其他效應of DIF
• DIF response is quick and reversible
– Adverse effects不良反應 of –DIF can be fixed修正
with a few days of 0 or + DIF
– Effects show up quickly反應快
• DIF and photoperiod
– As daylength , greater response to –DIF日長縮短，
對-DIF的反應更明顯
Slide 109
Limitations 限制of DIF
• Flower initiation誘導開花
– Poinsettia inhibited to flower at night temps
above 72°F聖誕紅在夜溫高於22.2oC不開花
• Seasons季節
– -DIF is not always achievable不見得達得到理
想的-DIF控制溫度(日溫低於夜溫)
– Summer in warm climates
– Sunny, clear days heat up g-house
Slide 110
DROP/DIP
• Lowering temp first few hrs of day日出前幾小時
降低溫度
– More effective than lowering temp at the end of day比
日落後降溫有效
– Majority of stem elongation occurs in these first
morning hrs莖部伸長多半發生在這幾小時
– Combining a morning DROP with slight – or 0 DIF is
better than more –DIF結合早晨的降溫與較小的-DIF
或0DIF會比較多的-DIF有效
– Drawing back thermal blanket or ventilating before
sunrise, good way to achieve DROP在日出前拉開保
溫膜或進行通風是達到DROP的好方法
Slide 111
Temp.
Midnight
Noon
Typical DROP/DIP daily
temperature pattern
8:00 pm
Slide 112
Graphical Tracking
Let you know
where your
crop is
compared to
where it
should be in
height
IMPORTANT
because of
shipping
container size
and aesthetic
appeal of crop
Slide 113
Graphical tracking used to determine temperature
requirements and other growth regulating practices.
Acceptable
finished height.
Above
Above this
this line,
line,
plants
plants too
too tall,
tall,
need
need growth
growth
regulation
regulation
Below
Below this
this line,
line,
plants
plants too
too short,
short,
need
need to
to elongate
elongate
plant
plant
Measure
representative
plants once or
twice a week and
adjust growing
techniques
accordingly.
Pot
Pot height
height
Before and just
after visible bud
is usually when
plants are most
responsive to
growth
regulation.
室外氣象站與
溫室溫控
方 煒
台大生機系教授
Slide 2
也是室內感測元件
風向計
風速計
光度計
溫、濕度計
雨感器
室外氣象站七大感測元件
雨量計
Slide 3
雨感器相關之控制策略
• 偵測下雨後的動作
– 關閉天窗，避免飄雨進入溫室
– 打開室外的遮蔭網，允許落雨來
刷洗溫室屋頂
Slide 4
風速計相關之控制策略
• 當室外風速高於某設定值時的動作
– 關閉室外的遮蔭網，避免被強風吹壞
Slide 5
風向計相關之控制策略
• 南北座向溫室，溫室屋頂有東西兩側
天窗，可分別控制且溫室有側窗
• 偵測到風由西、西北、西南方來臨時，
自然通風模式下可打開東側的天窗、
關閉西側天窗與打開西側側窗
• 偵測到風由東、東北、東南方來臨時，
自然通風模式下可打開西側的天窗、
關閉東側天窗與打開東側側窗
Slide 6
朝東/西面開口分別為天窗1/2
兩者可分別控制
Slide 7
溫、濕度計相關之控制策略
•
自然通風溫室
–
溫升或濕度過高時
1. 開天窗
2. 開側窗
–
溫降或濕度過低時
1. 關側窗
2. 關天窗
• 自然/強制通風溫室
–
溫升或濕度過高時
1. 開天窗
2. 開側窗
3. 關天窗,風扇啟動
溫降或濕度過低時
1. 關風扇，開天窗
2. 關側窗
3. 關天窗
風扇啟動時天窗與側窗關閉
風扇啟動時也可分階段，有時
搭配水牆啟動
Slide 8
濕度的相關參數設定
濕度的相關參數設定
Slide 9
天窗控制溼度
Slide 10
光度計相關控制策略
• 室外光量
– 控制室外遮蔭網開啟與關閉
– 控制室內遮蔭網開啟與關閉
• 室內累積光量
– 允許計算作物累積生長狀況
– 做為灌溉控制的依據
Slide 11
溫室內外PAR與累積日總PAR
Slide 12
溫、濕度複合控制策略
室內濕度過高，調降室內溫度控制設定值來提早換氣
室內濕度過低，調高室內溫度控制設定值來延緩換氣
Slide 13
由溫室內溫溼度計算蒸氣壓差
Slide 14
複合環控 (溫度與溼度)
Slide 15
溫度、光量複合控制策略
• 室內溫度未達高溫範圍
–允許提高光量設定值
• 室內溫度已達高溫範圍
–允許降低光量設定值
• 加溫模式
–白天：打開所有遮蔭網（不遮蔭）
–夜間：關閉所有遮蔭網與保溫膜
Slide 16
遮蔭網設定
晨間溫度較低允許較高光量
4
3
2
1
4
Slide 17
溫室溫控與相關英文
方煒 (台大生機系)
Dr. McMahon (園藝與作物科學系，Ohio 州立大學)
Slide 18
溫室溫控的目的在調節溫室內
作物生長與分化
Controlling Greenhouse
Temperatures to Manipulate
Greenhouse Crop Growth and
Development
Slide 19
Controlling greenhouse temperatures
involves moving heat into or out of a
greenhouse.控制溫室的溫度涉及將
熱量搬進與搬出溫室
Really though, we are talking about
moving heat into or out of a plant to
manipulate how it grows and
develops. 仔細想想，其實是涉及將
熱量搬進與搬出作物來調控其生長
與分化
Slide 20
First, a quick reminder about the differences between growth and development.
首先複習一下生長與分化的差異
Growth is an irreversible increase in mass (dry weight).生長指質量增加的不可
逆過程，Development is a sequential movement through life stages. 分化則
是指生命發展經歷的階段
Which plant (both are the same age) has the most growth, the most
development? 這兩株作物栽培了同樣長的時間，哪一株有最大
的生長，哪一株有最大的分化？We use temperature to
manipulate both growth and development.我們使用溫度來調控兩
者造成差異.
Slide 21
Moving or Transfering Heat
熱量的搬移或輸送
•
•
•
•
Conduction傳導
Convection對流
Thermal Radiation輻射
Evaporation蒸發
Slide 22
Conduction傳導
• Direct transfer of heat熱
量的直接傳遞
• Kinetic energy transferred
due to collisions由於分子
碰撞造成動能傳遞
• Billiard balls撞球
• Boiling water on electric
stove電爐上的熱水
Slide 23
Convection對流
• Air or fluid moves to new location to transfer heat
空氣或液體移動到新的位置來傳輸熱量
• Chimney effect 煙囪效應 (Passive ventilation自
然通風)
– Hot air rises, cold air sinks 熱空氣上升，冷空氣下降
• Convection oven 對流烤爐
• Forced air heating and air conditioning熱風加熱
與冷凍空調
Slide 24
Radiation輻射
• Heat energy released as
Electromagnetic Radiation
(EMR)熱能以電磁波方式輻射
• Everything above absolute zero
emits electromagnetic radiation
任何物體溫度在絕對零度以
上都會輻射電磁波
• Wein’s law煒恩定律
– As temperature , energy
emitted as shorter 溫度月高
的物體輻射出來的波長越短
• Plant loses most of heat this
way 作物多以此種方式損失熱
量
• Some greenhouses use radiant
heating systems有些溫室內使
用輻射加熱系統
Slide 25
Evaporation蒸發
• Heat transfer associated with phase change (liquid
to gas)熱量傳遞與相變(液態變氣態)相關
• Latent heat of vaporization蒸發潛熱
– Water 水 = 540 cal/mL; 1,064 Btu/lb
– High compared to other liquids液體中是蠻大的
• Plant cools itself by evaporating water from
stomates作物透過氣孔蒸發水分來散熱
• Evaporative cooling pads help cool some
greenhouses某些溫室透過蒸發冷卻水牆來協助
降溫
Slide 26
Energy Budget of Greenhouse溫室內能源的
收支 =Gains minus Losses進入的- 出去的
Heat Gains獲得的熱 Heat Losses損失的熱
• Solar radiation and
‘trapped’ heat太陽輻
射與出不去的熱
• Heating system加熱
系統
• Other machines機械
設備
– Fan motors風扇馬達
– Lamps/ballasts燈具/
安定器
• Conduction傳導
– Direct transfer of heat through
glazing material
Air layer in glazing reduces
conduction loses熱量可透過被覆材
料傳遞，雙層被覆材料之間的空氣
層有助於減少熱傳導
• Ventilation/Infiltration通風/滲漏
– Loss of heat and openings.熱量與開
口的損失
– Can be deliberate (summer cooling)
可以是經過精密計算的(夏季通風
降溫)or unwanted不要的 (drafts)賊
風
Slide 27
Greenhouse Effect 溫室效應
An unventilated greenhouse heats up from solar radiation because light
enters the greenhouse and much of what is not absorbed by the plants for
photosynthesis is absorbed or reflected back by plants and other objects.一間
不通風的溫室會被太陽輻射加熱，因為進來的光線大多未被作物吸收用
於光合作用或者被作物和其他物體反射
Slide 28
Greenhouse Effect 溫室效應
The absorbed light can be reemitted as heat radiation.
Most greenhouse glazing
materials are opaque (meaning
they don’t transmit) heat
radiation. This means that
energy is trapped and the
greenhouse heats up, often to
very high and life threatening
levels.被吸收的光線可以再
以熱輻射方式傳出. 但是大
多數溫室被覆資材對熱輻射
而言，都是不透明的；換言
之，熱量被限制在溫室內造
成溫室可能升溫到危害作物
的情況
Slide 29
Greenhouse Effect 溫室效應
The problem can occur at any season. In the
winter it occurs on very cold bright, sunny
days when the vents cannot be opened.這問
題可能發生在任何季節. 冬季發生在很冷
卻晴朗的日子當通風口完全未打開
Slide 30
Greenhouse effect 溫室效應
• Increased CO2 and other gas
levels in atmosphere大氣層中
二氧化碳與其他溫室氣體含
量提高
• Absorb sun’s energy and trap
the energy in the atmosphere,
much like glass greenhouse
traps sun’s heat inside溫室氣體
吸收了太陽能並將能量侷限
於大氣層中，就像玻璃溫室
限制熱量出去
• Gives greenhouse a ‘bad rap’溫
室被污名化
Slide 31
Energy Budget of a Plant
作物的能量收支
• Gains獲得
– Solar radiation太陽輻射
– Thermal radiation熱輻射
(from radiant heaters由輻
射加熱器獲得)
– Convection from warm air
與暖空氣的對流
• Losses損失
– Radiation輻射
– Transpiration*蒸散
– Convection to cool air與
冷空氣的對流
* Transpiration is the primary way in which a plant loses
energy, it is its primary cooling mechanism. That’s why
keeping plants well-watered on hot days is so important.蒸散
是作物散熱的主要途徑，這是作物主要的降溫機制。也
是為什麼在熱天讓植物有良好的灌溉是那麼重要。
Slide 32
Determining Greenhouse Heat Requirements
溫室加熱需求的計算
• Calculate heat loss from g-house計算溫室的熱損失
Q = [(A1* x U1) + (A2* x U2)] x (T -T ) x W x C
Inside
Outside
– A = Surface Area of exposed walls 溫室各屋頂與牆面表面積- calculated
by grower業者計算
– U = Conductance factor 傳導係數- provided by manufacturer廠商提供
– Ti – T0 = Temperature Differential 溫度差 - calculated from climate data由氣
象資料瞭解
– W = Wind Factor 風速因子- calculated from climate data由氣象資料計算
– C = Construction Factor 結構因子- provided by manufacturer廠商提供
• Q is how much heat a heating system must be able to supply.Q
是加熱系統所需提供的加溫需求
* The subscript indicates different wall/glazing materials, e.g. wood, glass, concrete, plastics, etc.)
Slide 33
You ALWAYS consider the:永遠需要考慮紀錄
中存在的
Coldest temperature recorded最低溫度
Hottest temperature recorded最高溫度
Greatest snowfall recorded最大降雪量
Highest wind recorded最大風速
Why???
Slide 34
RB
G
L
H
W
Surface Area = 2(L x H) + 2(W x H) + 2(L x RB) + (G x W)
What’s so important about knowing surface area when we’re
talking about heating and cooling a greenhouse???當我們在談
溫室的加熱或降溫，為什麼溫室的表面積這麼重要？
Slide 35
Heating Systems加熱系統
• Localized Heating局部加熱
– Heater per section
– Unit heater or forced-air heater
– Radiant heater
• Central heating中央加熱
– Heat created in central location and moved throughout
greenhouse
– Perimeter heating
– Floor heating
– Bench heating
• Solar heating system太陽能加熱
Slide 36
Unit heaters單元加熱機
• Combust fuel to heat air
which is moved by fan
(convection)使用燃油來加
熱空氣並透過風扇送風
• Efficient for heating small
spaces小空間加熱有效率
– (2000-6000 ft2)(200-600m2)
– Polyhouses塑膠布溫室
• 175,000 Btu/hr
• e.g. Reznor (as in Trent Reznor of
Nine Inch Nails), Modine
Slide 37
Air Distribution空氣輸送
Horizontal airflow (HAF)
fans
Convection tube from
forced air heater.
Slide 38
Typical HAF fan placement
室內均風風扇的典型安置方法
• At eave height, pointing straight ahead, 50’ apart在屋簷高
度、朝前、50呎距離
• Arrange so that air moves in a circular pattern through
house or section讓空氣在溫室內或該區域內造成環場的
效果
• Air speed = 50-100 fpm空氣流速
– Leaves slightly moving葉片輕微擺動
• Smallest fan possible風扇愈小越好
– Less electricity耗電小
– Less shading遮蔭小
• First fan in row各列的第一個風扇
– 10-15’ from wall 距離牆面10~15英呎
– Could be unit heater可以是單元加熱器
• Important for many reasons很重要基於多重原因
Slide 39
HAF’s Over Bedding Plants
安裝於花壇作物上方
Slide 40
Radiant Heating輻射加熱
• Iron pipe running length of greenhouse鐵管沿溫室走向安
裝
– One end一端– burner (nat. gas or methane)燃燒爐(天然氣或丙烷)
– Far end of pipe遠端 – exhaust (outside)室外排氣
• As pipe heats up, radiates infrared 鐵管被加熱就能輻射
能量
– 900°F = 3800nm
• Anything containing water (e.g. plants) absorbs this energy
任何含有水分的物體(譬如作物)都能吸收此輻射熱能
• Aluminum reflector to aim radiation at plants使用鋁製反
射片來讓輻射管路對準作物
Slide 41
Advantages of Radiant Heating
輻射加熱的優點
• Fuel bill reduction燃料成本降低
– Less heat lost in exhaust較少熱量損失
– Cooler air temp in greenhouse溫室內空氣溫度
較低
Disadvantage缺點
• Most temperature control systems measure air
temperature to adjust temperatures. With radiant heaters,
actual plant/leaf temperature should be measured.大多數溫
度控制系統靠量測空氣溫度來做控制，使用輻射加熱需
要能夠量測作物/葉片溫度
Slide 42
InfraRed Heaters
紅外線加熱器
Slide 43
Central Heating中央加熱
• Centralized boiler burns fuel中央鍋爐
– Larger variety of fuels可以使用多種燃料
• Boiler heats water to: 鍋爐把水加熱
– Hot water (180°F – US)熱水(82 oC)
– Steam (215°F)蒸氣(101 oC)
• Move hot water or steam around greenhouse with
pipes and release heat將熱水或蒸汽在溫室內透
過管路輸送來傳遞熱量
Slide 44
*Hot water* vs. Steam
• 1 Btu/lb of water as
temp 1°F
• Circulating pumps
• To get more heat:
– Pressurize system
– Stack pipes
– Finned pipes ( SA)
• Heating more uniform
throughout greenhouse
• Steam water 970 Btu/lb
+ 1 Btu/lb as temp 1°F
• Moves on its own
• More expensive to operate
• Less pipe needed but
stronger fittings
• Safety concerns
Slide 45
Distribution of Central Heat
• Heating pipes under bench
• Overhead pipes
• HAF fans circulate air
Slide 46
Floor Heating地底加熱
• Most sense with floor
production
• Can only use hot water
– Steam too hot
• Plastic tubing in
concrete floor
• Heat supplied where
plants are located
• Floor dries faster after
getting wet.
Slide 47
Floor Heating Systems
Floor heating units and
pipes in a foliage house.
Floor heating unit in a
bedding plant house.
Slide 48
Bench Heating植床上底部加熱
• Bottom heat
• Plastic tubes with hot
water directly on
bench
• e.g. BiothermTM
• Single hot water
heater usually
sufficient
• Propagation
Slide 49
‘Bottom’ Heat for Benches used
for propagation and/or growing
Slide 50
Fuel Comparison (Hot water)
熱水系統的燃料比較
Fuel
Cost
Efficiency
(Btu/$)
Delivery
Bituminous
Coal
$41/ton
639,000
Hard to store,
shoveling?
#2 fuel oil
$0.84/gal
126,000
Buried tank
Natural gas*
$4.69/
1000ft3
229,000
Pipeline
Slide 51
Combustion Concerns 燃燒相關
• Vent heater exhaust to outside of greenhouse
– Ethylene (C2H4) generation from incomplete
combustion.
– Other unwanted products from incomplete
combustion (CO, sulfur compounds, etc.)
– Avoid re-entry of exhaust through ventilation
Slide 52
Solar Heating太陽能加熱
• Collect energy from sun and use for heating
– Store as hot water or rock
• Back-up heating system
• Expensive and to date not very efficient
Slide 53
Comparison of heating systems
加熱系統比較
Heating
system
Installation
costs
Fuel Used
Heat Transferred
to Plants
Unit
heaters
Radiant
heater
Central
heating
$0.501.00/ft2
$1.502.25/ft2
$2.503.25/ft2
N.g., P, K,
#2 oil
N.g., M
Convection
Wood, oil,
coal, N.g.
Convection
Solar
heating
$8-10/ft2
Sun
Convection/
Radiation
Radiation
Slide 54
Heat Conservation 節能的方法
• Reduced Surface Area to Volume
(SA/V)降低溫室總表面積對總
體積的比例
– Multiridged greenhouse連棟
• Double-layer glazing雙層被覆
• Thermal screen節能保溫膜
– Shade or black cloth
• Wall insulation牆壁隔熱
• Windbreaks 溫室外設立風阻
• Cool temperature crops選擇低溫
作物
Slide 55
Cooling and Ventilation
Slide 56
Why Ventilate? 為什麼要通風
1.
Reduce air temperature
降低空氣溫度
2.
Replenish補充CO2
Outside ~380 ppm, inside
can be much lower
3.
Reduce relative
humidity降低相對濕度
Condensation on leaves
Disease減少葉片的水
分凝結就能降低發生疾
病機率
Slide 57
Natural/Passive Ventilation
自然/被動通風
• Chimney effect – convection 煙囪效應 – 對流
– Buoyancy浮力
• Warm, less dense air rises暖空氣較輕，上升
• Cooler, more dense air sinks冷空氣較重，下降
• N-S orientation uses
prevailing west winds 南
北向可利用西向風
Slide 58
The effectiveness of passive ventilation is most
effective when side vents can be opened to increase
airflow out the top vent 最有效的自然通風是側窗
與上方開口都能打開
Slide 59
Staged Vents 分階段的開口
• As temp ↑, 溫升
– Open ridge vents先開上方開口
– Open side vents再開側窗
• As temp , 溫降
– Close side vents先關側窗
– Close ridge vents再關上方開口
• Manual or automated control
(connect to thermostat) and
program to open/close vents in
proper sequence. 手動或自動控
制都需要依照正確順序
Slide 60
Side Vents 側邊通風口
Slide 61
Advanced Passive Ventilation
先進的自然通風
With advent of plastics and
better engineering, able to
passive ventilation to
adequate levels
Slide 62
Vents can provide an entry for insects. 屋頂開口可能
有昆蟲進入Screening can be used to exclude insects.
防蟲網可以使用
Slide 63
In contrast to passive ventilation, many
greenhouses rely on mechanical (fan or
forced) ventilation system.
除了自然通風的溫室之外，許多溫室
仰賴強制通風
Slide 64
Mechanical or Fan or forced
Ventilation 機械(強制)通風
• Exhaust or ventilator fans
supplement natural ventilation
• Locate on side opposite
prevailing winds安裝於迎風
面對側
– Pull air through ghse.
• Exchange all air in greenhouse
once per minute維持每分鐘換
氣一次
• Distance from inlet to exhaust
no more than 150’空氣進出口
距離不超過45.7m.
Slide 65
Determining Cooling Requirement
降溫需求的決定
• 1 complete air exchange per minute每分鐘一個溫
室體積的空氣交換量
• Volume of greenhouse = volume of air to be
moved溫室體積=風扇必須搬運的空氣量
• Fan capacity = amount of air each fan moves風扇
能力=風扇可以搬運的空氣量
– Measured in cfm (cubic feet per min)以cfm為單位或
m3/s或m3/min
• Better to have two smaller fans than one big fan
兩個小風扇比一個大風扇好
– More uniform cooling降溫更均勻
– No more than 25’ apart相隔不超過7.6m
Slide 66
RB
G
L
H
W
L x W x H + (L x W x G)/2 = Volume
Why is volume important when designing cooling systems?
當要計算溫室降溫通風時，為什麼溫室體積的計算很重要
Slide 67
Fan Ventilation Stages
強制通風的控制分段
•
•
If fan running, ridge vent
closed風扇啟動時天窗與
側窗關閉
As temp ,溫升
1.
2.
3.
Open ridge vents開天窗
Open side vents開側窗
Close ridge, fans on關天窗與
側窗，開風扇
As temp ,溫降
1.
2.
3.
Fans off, open ridge關風扇，
開天窗
Close side vents關側窗
Close ridge vent關天窗
Slide 68
Fan Components風機組成
Louvers – “blinds” for fan 百葉
Closed while fan not in use風扇不用時關閉
In line with g-house wall與牆面對齊
Keep wind and rain out擋風與擋雨
Screen鐵網
Outside of fan安裝於風扇外
Mesh opening網目開口 1 in2
Safety reasons安全理由
Slide 69
Evaporative Cooling Pads
蒸發冷卻水簾片
Corrugated cellulose pad
located on opposite wall from
ventilator fans (windward
side)
• Water flows over and through
the cooling pad
• Fans pull warm outside air
through cooling pad
• Water absorbs heat from the
air as it evaporates which
cools the air as it enters the
greenhouse
540 cal/g of water!
That’s a lot of cooling
capability
Slide 70
Pad & Fan Specifications
•
•
•
•
•
Pad & fan systems work best when RH low
Optimal pad to fan distance = 100-150’
1 ft2 pad for 150 ft3 air per min
Correct for elevation and distance
Typically 4 or 8” thick 一般10或20公分厚
Slide 71
More on Cooling Pads
• Water distributed at top of the pad
– ½ gal per min per linear foot
– Recycled in sump tank
• Algae problems?長藻的問題
– Disinfectant in circulating water
• Small insects (e.g. thrips) sucked in小昆蟲
(譬如薊馬)被吸入
– Treat water with insecticide以殺蟲劑處理用水
Slide 72
Swamp or Package Coolers
單元式冷風機
• Evaporative coolers for small greenhouses小
溫室使用蒸發冷卻的冷風機
– Hobby greenhouse, small rooms
– Air drawn in by fan across cooling pads
• Cool air “pushed” into greenhouse冷空氣被
吹入溫室
Slide 73
Fog Cooling Systems
• Fog is created in the greenhouse在溫室內
造霧
– Water forced through small nozzles at high
pressure (~1000 psi)高壓噴霧產生小霧滴
• As fog evaporates, takes heat out of air
• Cannot use hard water, clogs nozzles不能使
用硬水，會使噴嘴阻塞
• Humidistat → 80-90% RH
Slide 74
Shading as Cooling Mechanism
以遮蔭來降溫
• Reduce light intensity and
reduce temperature透過降
低入射光量來降溫
– Shade Cloth遮蔭網
– Shading Compound塗料
• Adjust light intensity for
high quality crops調整光
量種出高品質作物
Slide 75
Shading as Cooling Mechanism
• Shade Cloth遮蔭網
– Can be applied and
removed as needed收放自
如
– Can be mechanized or
under computer control可
機械化與電腦化控制
– Does not reduce the radiant
energy (heat load) entering
the greenhouse安裝於室內
則無法減少進入的能量
Slide 76
Shading as Cooling Mechanism
• Shading Compound遮蔭塗料
– Cannot be removed and applied as
needed無法收放自如
– Must be manually removed in fall
在秋季必須人工清除
– Have to use specially formulated
shading compound有特殊配方
– Does reduce radiant heat load in
the greenhouse可減少進入溫室的
熱負荷
Slide 77
Winter Cooling Systems冬季降溫
• Passive ventilation被動通風
– Open ridge vents開天窗
– Have to be sure they do not
freeze open!確認不會被凍住
• Active cooling 主動降溫
– Convection tube通風管
• Bring in cool outside air or
circulate cooler air from ridge
area引入室外冷空氣會做內循
環
– HAF fan systems
• Draw cool air down from ridge
area由屋脊拉下較冷空氣
On bright, sunny subzero winter days, unvented greenhouses
can have temps well over 100F (37oC). Bad for plants and
workers.
Slide 78
Measuring Temperature溫度的量測
• Place sensors as close to plants
as possible and not in direct sun
• Aspirated thermostat 通風的溫
度計
– Fan blows air across thermometer
– Prevents ‘dead air’ space from
developing around the sensor
– Gives more accurate reading of
temperature
– Within 2-3° of real temp rather
than 4-5° with non-aspirated unit
Slide 79
室內溫、濕度感測器
Slide 80
Using temperature to
control plant growth.
使用溫度控制作物生長
Slide 81
Temperatures in Greenhouse
溫室內的溫度
• Air temperature空氣溫度
– Most commonly and easily measured最容易量測
– Night temp easier to control than day夜間溫度比白天
容易控制
• Leaf temperature葉片溫度
– Difficult to measure不容易量測
– Most likely different from air temp與空氣溫度多半不
同
• Media temperature介質溫度
– Roots根系
– Propagation種苗繁殖
Slide 82
How Temperature Affects Plants
溫度如何影響作物
• Flower induction in some species誘導開花
– e.g. Easter lily、Phalaenopsis 百合、蝴蝶蘭
• Interacts with photoperiod to control floral induction
與光週期合併來控制開花
– Heat delay
• Bud dormancy or vernalization花苞休眠或春化
– e.g. hydrangea & azalea繡球花與杜鵑
• Controls rate of stem elongation控制莖生長長度
– *Most important最重要
Slide 83
Adverse Effects of Temperature
溫度的不利影響
• Chilling injury often occurs at less than 50°F/10°C
–
–
–
–
–
–
–
African violets
Poinsettias聖誕紅
Hibiscus木槿
Gloxinia大岩桐
Tomatoes蕃茄
Foliage plants觀葉植物
Phalaenopsis蝴蝶蘭
• Chilling injury - membrane dysfunction膜功能障礙
Lipids in tropical and subtropical plant membranes solidify
Slide 84
Growth vs. Development
• Growth生長
– Increase in size
(volume or weight) of
plant or organ that is
irreversible and
permanent
• Development分化
– Aging process of the
plant – phases that
plant goes through as
gets older
•
•
•
•
•
Germination
Vegetative growth
Flowering
Fruit set
Seed release
Slide 85
Growth Rates of Plants
作物的生長速率
• Growth rate = The speed at which an organ
goes through a certain developmental stage
– Stem growth
– Flower production
– Leaf unfolding
• All growth processes have different
temperature response curves所有的生長過程
都有不同的溫度反應曲線
– Even within species即使是相同品種
– Cultivar specific依品系而定
Slide 86
Optimal Temperature最適溫度
• Every species has both optimal and tolerable temperature
range for growth各品種都有最適與可容忍的溫度範圍
• Optimal range: produce high quality plants most rapidly
最適範圍:可最快長成最高品質
– Mums = 61-64°F (night)菊花:16~17oC夜溫
• Tolerable range: still grow but more time and lower
quality可容忍範圍:仍可生長但是既慢且低品質
– Mums = 40-60°F & 65-80°F (night)
Slide 87
Cumulative Growth累積生長
• Instantaneous plant temperature controls growth at
any moment各瞬時的作物溫度控制當時的作物生
長
• Cumulative growth in 24 hr = average of individual
growth rates during that period累積24小時的作物生
長代表在該時段內作物的平均生長狀況
• Manipulating average daily temperature in the
greenhouse (within tolerable range) will change the
rate of plant development調控溫室內的日總平均溫
度可以改變作物分化速率
– Fast growth high quality growth長得快不代表高品質
Slide 88
Average Daily Temperature
日總溫度平均值
Greenhouse growers have target temps for day
and night溫室業者有設定的日溫與夜溫
Can calculate an average daily temp.
Weighted average加權平均
– Day 16 hr @ 77°F日間16小時，平均溫度77°F
– Night 8 hr @ 68°F夜間8小時，平均溫度68°F
– Weighted Avg. temp加權平均溫度
= [(16x77)+(8x68)]/24 = 74°F
Slide 89
Growth Curve生長曲線
Maximum
Maximum is
usually not
optimum.
最大通常不代表
最佳
Optimum is the
temp. that has
the plant at the
stage you want it
to be at!!!!!!
最佳溫度決定於
你希望作物的生
長速率是多少
Slide 90
Growth Curve
• Linear Range: portion of curve that is a
straight line線性範圍
• Base temperature: intersection of the straight
line (linear range) and the X-axis (X-intercept)
基礎溫度
• Maximum temperature: peak of growth rate
curve最大溫度
Slide 91
Degree-day Concept
度日數的觀念
• Slope: Dy/Dx Change in growth rate / change in temp
• e.g.# leaves/day/°F → leaf unfolding
• e.g. inches/day/°F → stem elongation
• Daily increase in leaf production or stem
elongation as you raise the average temp 1°F平
均溫度增加1°F，葉片生長或莖長的每天增加
量
Slide 92
Degree-day Concept
• The amount of heat (or degree-days) above the
base temp that must accumulate for a
developmental event to occur在基礎溫度以上累
積的熱量都用來提供作物生長發育所需
• 1 degree-day will accumulate when the day’s
average temp is 1°F above base temp
– Average temp = 55°F
– Base temp = 50°F
– 5 degree-days will accumulate that day
Slide 93
Degree-day Concept
• Degree-day constant associated with every
development stage 度日數與每個分化階段都相關
– e.g. 80 degree-days needed to reach a certain stage
• All of the following would accumulate 80 degreedays以下的幾項都可得到累積的80度日數
– 80 days @ 1° above base temp
– 40 days @ 2° above base temp
– 8 days @ 10° above base temp
• Allows crop growers to schedule and time crop
development允許作物栽培者可以用來針對作物的
生長分化進行規劃與排程
Slide 94
Application of Degree-days度日數的應用
(hypothetical numbers使用假設的數字)
• Easter Lily production during leaf development
– Slope = 0.02 leaves/degree-day
– Degree-day constant = 1/0.02 ≈50
• 50 degree-days/leaf
– What temp to produce 3 leaves in 10 days?
– Avg daily temp = total degree-days + Tbase*
desired time
* Tbase = base temperature
Slide 95
Example cont’d
• What avg. daily temp to produce 3 Easter lily
leaves in 10 days?
– Base temp = 55°F
• Avg temp = 3 x 50 + 55
≈ 70F
10
Maintain 70F avg. temp and you should have 3
new leaves in 10 days!
Slide 96
• Most E. Lily growers use a ‘bud meter’ once flower
buds are visible.百合業者使用花苞長度量尺
By measuring the
length of the bud, the
grower knows how
warm to keep the
greenhouse to get the
bud to the selling stage
by Easter. The bud
meter is based on
degree days.
量測花苞的長度，業者可以瞭解溫室溫度需
設定多少度才能趕上復活節銷售旺季。此
花苞量尺的設計就是依據度日數。
Slide 97
Original Applications of Degree-days
度日數的早期應用
• Field-grown crops田間栽培作物
– Count degree-days by measuring temp由量測溫度來計算
度日數
– Predict days to harvest預測收穫時間
• Apples蘋果: bloom開花 → harvest收穫 = 2800 degree-days
– Predict insect hatching/molting 預測昆蟲孵化/蛻皮
• Degree-days = (Tmax – Tmin)/2 – Tbase
• Prediction only - growers of field-grown crops have
no control over temperature 只能預測-因為田間溫
度無法控制
Slide 98
Temperature and
Growth (stem height) Regulation
溫度與株高調控
Slide 99
History of DIF
• Originally discovered in 1944
• “Rediscovered” and developed as a growth
regulation technique生長調節技術 in late 1980’s
by Dr. Royal Heins at MSU
• The DIFference between day and night
temperature in a greenhouse will affect internode
elongation and consequently, stem length.溫室內
日溫與夜溫的差會影響節間長度，影響莖高
Slide 100
DIF
DIF = Day temp日溫– Night temp夜溫
+ DIF when Day temp> Night temp
0 DIF when Day temp = Night temp
- DIF when Day temp < Night temp
Slide 101
DIF effects on internode elongation:
Within normal growing temperatures,
the more positive the DIF, the longer
the internodes.在正常生長狀況下，
DIF值正的越多，節間長度越長
Slide 102
Greenhouse
A
B
C
Day temp
60°F
55°F
50°F
Night temp
50°F
55°F
60°F
Avg. Daily
temp
DIF
55°F
55°F
55°F
+10
0
-10
Internode
length (plant
height)
Tall
Medium
Short
Slide 103
Effect of DIF on Stem Elongation
Slide 104
DIF Responding Species
受DIF影響的品種
•
•
•
•
•
•
•
•
•
Easter lilies百合
Poinsettias聖誕紅
Snapdragon金魚藻
Rose玫瑰
Petunia牽牛花
Carnation康乃馨
Impatiens鳳仙花
Tomato蕃茄
Pepper小黃瓜
DO NOT RESPOND
• Hyancith風信子
• Tulip鬱金香
• Narcissus水仙
• Squash南瓜
Slide 105
Degree-days vs. DIF
• Avg. daily temp (or degree-day accumulation)
control rate of plant development日總平均溫度
或者總度日數控制作物的生長速率
• DIF responsible only for plant height regulation
(internode elongation)DIF只用來調節作物的生
長高度(節間長度)
– More positive DIF → the taller the plant長得高
– More negative DIF → the shorter the plant長得矮
Slide 106
Greenhouse
A
B
C
Day temp
60°F
55°F
50°F
Night temp
50°F
55°F
60°F
Avg. Daily
temp
DIF
Internode
length (plant
height)
55°F
55°F
55°F
+10
Tall
0
Medium
-10
Short
Which greenhouse would have the tallest plants? The
shortest? The furthest along in development?
Slide 107
Side Effects 副作用
of Extreme極端的–DIF
• Chlorosis缺綠病;變色病 (esp.
DIF < -10F)
– Bedding plants (e.g. salvia)
• Leaf orientation 葉片走向
– Problem on Easter Lily
– (photos courtesy of Dr. Harold
Wilkins)
Slide 108
Other effects 其他效應of DIF
• DIF response is quick and reversible
– Adverse effects不良反應 of –DIF can be fixed修正
with a few days of 0 or + DIF
– Effects show up quickly反應快
• DIF and photoperiod
– As daylength , greater response to –DIF日長縮短，
對-DIF的反應更明顯
Slide 109
Limitations 限制of DIF
• Flower initiation誘導開花
– Poinsettia inhibited to flower at night temps
above 72°F聖誕紅在夜溫高於22.2oC不開花
• Seasons季節
– -DIF is not always achievable不見得達得到理
想的-DIF控制溫度(日溫低於夜溫)
– Summer in warm climates
– Sunny, clear days heat up g-house
Slide 110
DROP/DIP
• Lowering temp first few hrs of day日出前幾小時
降低溫度
– More effective than lowering temp at the end of day比
日落後降溫有效
– Majority of stem elongation occurs in these first
morning hrs莖部伸長多半發生在這幾小時
– Combining a morning DROP with slight – or 0 DIF is
better than more –DIF結合早晨的降溫與較小的-DIF
或0DIF會比較多的-DIF有效
– Drawing back thermal blanket or ventilating before
sunrise, good way to achieve DROP在日出前拉開保
溫膜或進行通風是達到DROP的好方法
Slide 111
Temp.
Midnight
Noon
Typical DROP/DIP daily
temperature pattern
8:00 pm
Slide 112
Graphical Tracking
Let you know
where your
crop is
compared to
where it
should be in
height
IMPORTANT
because of
shipping
container size
and aesthetic
appeal of crop
Slide 113
Graphical tracking used to determine temperature
requirements and other growth regulating practices.
Acceptable
finished height.
Above
Above this
this line,
line,
plants
plants too
too tall,
tall,
need
need growth
growth
regulation
regulation
Below
Below this
this line,
line,
plants
plants too
too short,
short,
need
need to
to elongate
elongate
plant
plant
Measure
representative
plants once or
twice a week and
adjust growing
techniques
accordingly.
Pot
Pot height
height
Before and just
after visible bud
is usually when
plants are most
responsive to
growth
regulation.