Transcript Selling an Idea or a Product

The Benefits of Heat Pipes in
Hot & Humid Climates
Allan Westbury
Managing Director
S & P Coils Ltd.
Leicester, UK
Presentation Contents

Problems of Hot & Humid Climatic
Conditions

What is a Heat Pipe?

Heat Pipes & how they can HELP

Conclusion
Problems of Hot & Humid
Climates

Main influences on comfort:





Dry bulb temperature
Air speed
Air humidity
Radiation
Ideal Comfort Conditions:


RH 40 - 60 %
Temperature 20 - 23°C (68 - 75°F)
Proper humidity levels
ASHRAE Recommended
Safety margin
Health Problems
0
10
20
Mildew Growth
30
40
50
60
70
80
90
100
% Relative Humidity
Typical Ambient conditions
35°C @ 80% RH
45°C @ 30% RH
35°C @ 20% RH
20°C @ 90% RH
35°C @ 80% RH
45°C @ 30% RH
20°C @ 90% RH
35°C @ 20% RH
Comfort conditions
35°C @ 80% RH
Comfort condition,
20 to 24°C,
40 to 70% RH
45°C @ 30% RH
20°C @ 90% RH
35°C @ 20% RH
Historical Air Conditioning
Examples of wind towers
on some older buildings.
Modern Air Conditioning
Dubai Convention Centre
Pyramid Centre
Mercato Mall
Doha – Sheraton Hotel
Decorative features
Recent Practice

Air is cooled to supply conditions
Warm humid
air, 42°C
Condensation
Saturated
air, 18°C
Recent Practice
Taking a point in this
envelope, 42°C @ 35% RH,
and then cooling to 18°C
the air becomes saturated
and unsuitable for
supply.
Recent Practice

If this saturated air with a high
moisture content is supplied into
the space we will have two major
problems:
Problem 1
The building occupants will feel very
uncomfortable and health problems may
arise.
HOTEL
OFFICE
Dissatisfied, unhappy
customers and even potential
insurance claims.
Reduction in employee
efficiency and, at worst, lost
working days due to sickness.
Problem 2
•
•
•
•
The building fabric and fittings will deteriorate
due to the high moisture levels creating
excessive maintenance costs.
This can manifest itself in several ways
Discolouration of walls
Mould growth
Corrosion of metalworks
Detachment of tiles etc. from walls/ceilings
Dehumidifying with coils

Generally the air is overcooled
Comfortable air,
18- 22°C
Warm humid
air, 42°C
Condensation
Reheat Coil
Increase in running costs
Overcooling the air and
then re-heating gives rise
to additional cooling &
heating loads.
A
B
C
D
The downside of reheat

The cost of reheating the air is
high.

It also means we have to
include a whole package of
extra equipment and controls.
The pay-off




Overcooling means an increased cooling
load.
= increased running costs.
This in turn means a larger chiller unit.
= increased capital costs.
Re-heating will require energy.
= increased running costs.
Re-heating also adds equipment and
complexity.= increased capital costs.
The Economic Solution



So, while the theory is very attractive, the
economics present a large deterrent.
Ideally we would like to cool the air to a
comfortable temperature and remove
moisture, but without the need for expensive
reheat.
It sounds impossible, but by using heat
pipes it can be achieved.
Heat Pipes

The principle of heat pipe operation

Heat Pipes and dehumidification

Heat Pipes and heat recovery
What is a Heat Pipe ?

A heat pipe is an extremely efficient
conductor of heat.

By using the latent capacity of the fluid the
heat pipe transfers heat at a very high rate.
Basic principle of operation
A simple heat pipe
comprises a hollow
tube partly filled
with a working fluid
Using the latent
capacity of the fluid,
we can transfer large
amounts of heat very
rapidly from a hot
point to a cold point
on the tube wall.
Heat
out
Heat
in
Heat
out
Heat
in
Summary of Characteristics



Heat is transferred by latent means giving a
heat transfer rate of around 1000 times that
of a solid copper rod
Vaporisation and condensation take place at
the same temperature allowing high heat
transfer at low temperature differences
Heat pipes without wicks (Thermosyphons)
rely on gravity to return the condensed
liquid.
Heat Pipe applications
1.) Heat Pipes for enhanced
dehumidification.
Adding a Heat Pipe

The heat pipe improves the efficiency of the
system.
18°C
42°C
36°C
12°C
Heat Pipe in practice

Plan view of cooling coil.
Heat Pipe
pre-cool
Airflow
42/28.5°C
36/27.1°C
Heat Pipe
re-heat
Cooling
Coil
Airflow
18/14.1°C
12/11.8°C
o
18 / 14.1 C
o
42 / 28.5oC
Airflow
36 / 27.1 C
12 / 11.8oC
2-Row ‘Horseshoe’.

‘Horseshoe’ Heat Pipes
are used either for
original supply or for
retrofit applications.

The unit will be
installed around an
existing cooling coil.
2-Row ‘Combi Coil’.
Heat Pipe Effect
1-2 Heat Pipe pre-cool
2-3 Cooling coil
3-4 Heat Pipe re-heat
Resultant energy
saving of up
to 30%.
3
4
2
1
In Practice
If the heatpipe is designed
for a maximum temperature.
What would the off condition
be at other conditions?
Economic Design

Base design on commonest conditions not
maximum conditions.

This in turn means removing need for
additional reheat.

For close control some additional cooling
may be required.
Bin Data

By using Bin Data we can identify the
commonest or average condition.
Worked Example
Based on average ambient
condition, 32 °C @ 58% RH.
Cooling load - 51.3kW
Heating load - 7.2kW
Total load - 58.5kW
Worked Example
Air
Addvolume
in the Heat
: 4.0 Pipe,
m3/s
Air
Heat
on:
Pipe
40/27.8°C,
Pre-cool40%RH
- 7.2kW
Supply
Heat Pipe
air Re-heat
to room:- 7.2kW
20/14.8°C
New Clg load - 44.1kW
New Htg load - 0kW
Saving 14.4kW
Worked Example
At
alternative
If the
final airconditions:
condition is
Heat
Pipeatpre-cool
: 9.5 akW
required
18 °C, then
Heat
Pipe re-heat
: 9.5
secondary
cooling
unitkW
Cooling load - 54.3kW
can trim the temperature.
Heating load - 0kW
Saving 19kW
Secondary Cooling Schematic
Primary Cooling
Secondary Cooling
19.5 / 14.5oC
(60%RH)
Fan Coil Unit
o
38 / 27.5 C
(45% RH)
o
18 / 14 C
(65% RH)
FAHU
Air Handling Unit
18 / 14oC
(65% RH)
Duct Mounted Coil
o
18 / 14 C
(65% RH)
Summary






Requires no energy to run, being “driven” by
the cooling coil.
Nett energy savings of around 30% compared
to standard cooling and reheat.
Lower cooling load = smaller chiller/
compressor.
Design for average conditions to eliminate
reheat.
Easy installation.
Controlled by the cooling coil.
Heat Pipe applications
2.) Heat and “coolth” recovery.
Heat and “coolth” recovery
Used to transfer heat between supply
and exhaust air streams where :
There is a large difference between supply
and exhaust temperatures.

There are high air volumes involved.
Efficiencies of up to 65% can be achieved
giving significant energy savings.
Basic design features




The Heat Pipe unit straddles the supply and
exhaust ducts
A centre tube plate prevents cross
contamination between airflows
No pump requirement to transfer the heat as
with a run around coil system
Airstreams must be in counterflow
Orientation


Available in both
vertical & horizontal
arrangements.
The warmer
airstream must be at
the bottom in the
vertical mode.
Exhaust Air
Supply Air
Horizontal orientation
Benefits

Requires no energy to run.

No maintenance.

No cross contamination.

Can be sized to suit the ductwork or AHU.

Easy condensation removal.
Conclusion





Heat Pipes are extremely efficient heat
transfer devices
By installing across supply and exhaust ducts
we can recover waste energy.
Typical efficiencies – 50% to 60 %
By wrapping The Heat Pipe around a cooling
coil we bypass a certain amount of heat,
saving on the cooling load and giving free
reheat.
Nett energy savings - around 30 %
Completed projects
Contractor
Consultant
Garmco BAH
Al Hamad - Shj.
AHU Supplier
Qty.
Type of
Project
York
Artek
SAS Raddison Muscat
Project
Aluminium Store
Clever
8
New
Pyramid shopping center
Saiver
4
Retrofit
Raddison
Thermo - Dubai
Mario & Ass.
SKM
2
Retrofit
Crown Plaza
Al Hamed
GHQ
Carrier
3
Retrofit
MW-1699
Nael Est. - Al Ain
Syna dev.
Clever
4
New
Hiltonia Beach
Al Hamad - Shj.
Clever
2
New
Samar Tower- Shj.
Al Hamad - Shj.
Clever
2
New
Al Ansari Bldg.
Geco - Sharjah
Sharjah Municipality
SKM
6
New
Swimm. Pool
Sensaire - Dubai
Dubai Municipality
Clever
3
New
Children's City
Saiver
2
Retrofit
City Center
Majid Al Futtaim
Verger Delport
W.S. Atkins
York
145
New
Industrial city - ADH
Viking
RPW
Viking
2
New
Al Nahdha Shopping
Viking
RPW
Viking
2
New
Sharjah Mega Mall
Al Futtaim
Arab Consultants
SKM
1
New
Sharjah Cricket Stadium
ETA
Spectrum - Delhi
Novair
5
New
Grand Hayat - Mumbai
Carrier
Carrier
37
Retrofit
Le-Meridian - Dubai
Gibca - Sharjah
Petra
1
Retrofit
Coral Beach Resort
Completed projects (Cont..)
Type of
Project
Contractor
Consultant
AHU Supplier
Qty.
Transgulf
RPW
York
8
New
Spinneys - Jumeira
ETA
RMJM
Clever
33
New
World Convention centre
Geco - Sharjah
Cab - Sharjah
SKM
90
New
Indoor Sports Hall
B K Gulf
RMJM
Interklima
6
New
World Convention centre
Sensaire - Dubai
Arif & Bintouk
Carrier
8
New
Novotel & Ibis Hotel
Clever
4
New
Coral Beach Resort
Gibca - Sharjah
Project
Transgulf
RPW
York
24
New
Royal Mirage hotel
Remco
Shadid Engg.
Euroclima
6
New
Dubai Women's association
Mekar
RMJM
Mekar
30
New
Exhibition Hall 1 & 2
DPA
Aftron
1
New
DPA club
Shadid Engg.
Carrier
1
New
Emaar bank
Gulf Star - ADH
Pvt. Deptt.
SKM
2
New
pvt. Villa at Jebel Dana
SKM - Sharjah
Ian Banhem
SKM
8
New
Kharbash Bldg.
Al Turath
Clever
14
New
Wedding hall
McQuay
Mott / EMS
McQuay
6
New
West Side Marina
FNC
Arkiteknik
Dunham Bush
41
New
Neighborhood centre
Gemac
Mekar
2
Retrofit
Ruler's villa
Artek
Junker
8
New
Dawoodi Bohra center
Al Futtaim
Carrier
Dhabi Contracting
Bu-Haleeba
Junker
Dehumidification selection
Heat Recovery Selection
Any Questions ?
For further information or to download latest
copies of our selection software, visit our
website:
www.spcoils.co.uk
HEAT PIPES:
The Benefits of Heat Pipes in Hot & Humid Climates
Allan Westbury
Managing Director
S & P Coils Ltd. Leicester, UK
Problems of Hot & Humid Climatic Conditions

Main influences on comfort:





Dry bulb temperature
Air speed
Air humidity
Radiation
Ideal Comfort Conditions:


RH 40 - 60 %
Temperature 20 - 23°C (68 - 75°F)