CHEMICAL ENGINEER
University of Valladolid
Chemical Engineering Laboratory II
CHILLING ADSORPTION
Ana Celina Gondim Santos
Sara Pérez Nieto
(Group B - 22)
Valladolid, 20 de Octubre de 2011
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1. INTRODUCTION
2. ADSORPTION REFRIGERATOR
3. RESEARCHS
4. APLICATIONS
5. CONCLUSIONS
3/27
1. INTRODUCTION
Cooling adsorption systems
Oil crisis (1970)
Ecological problems (1990)
Advantages:
● environmentally friendly refrigerants
● can recover waste heat at low temperature levels
● low operation costs
Evaluation of an Adsorption cooling system:
● coefficient of performance (COP)
● specific cooling power (SCP)
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2. ADSORPTION REFRIGERATOR
2.1 System configuration and operation
ADSORBENT
ADSORBATE
Figure 1. General basis system layout of the adsorption chiller.
Adsorbent cooling:
Adsorbent heating:
adsorption process +
refrigerant evaporation
desorption process +
refrigerant condensation
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2. ADSORPTION REFRIGERATOR
2.1 System configuration and operation
Figure 2. Photograph of the silica gel-water adsorption chiller.
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2. ADSORPTION REFRIGERATOR
2.1 System configuration and operation
Figure 3. The adsorption icemaker
during ice production.
Figure 4. Solar-powered icemaker
without valves.
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2. ADSORPTION REFRIGERATOR
2.2 Parameters of work
Parameters that influence in the performance of
the system:
● Temperature of cooling water
● Adsorption temperature
● Heating source temperature
● Desorption temperature
● Cycle time
load control tool
T↑ and madsorbed ↓ (Pconst)
T↑ and P↑ (madsorbed-const)
to get more cooling.
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2. ADSORPTION REFRIGERATOR
2.3 Key issues for the development of adsorption
systems
● The hight cost of production is a drawback for
adsorption systems.
● To become more commercially attractive,
it is
necessary to make a cost and size reduction:
Increasing the SCP throught enhancement of the
internal and external heat transfer of the adsorber;
● Increasing the COP throught the improvement of the
heat management.
●
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2. ADSORPTION REFRIGERATOR
2.3 Key issues for the development of adsorption
systems
The main technologies to enhance the external
heat transfer are related to:
extended surfaces: to increase of the heat
exchange
area;
● coated adsorbers: to increase the wall heat transfer
coefficient;
● heat pipe technology: to have a high heat flux density
and less intermediate elements.
●
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2. ADSORPTION REFRIGERATOR
2.3 Key issues for the development of adsorption
systems
The main technologies to enhance the internal
heat transfer are related to:
consolidated adsorbents: because consolidated
adsorbents have lower mass transfer properties than
granular adsorbents, which could lead to very low
adsorption rates.
●
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3. RESEARCHS
3.1 Researches tendency
Increase in adsorption cooling systems
performance → compete with electric compression
machines.
●
Adsorbents
● R&D develop performing
Components
Sistems
Harmonization of
thermodynamic cycle.
●
the
adsorbent
with
the
12/27
3. RESEARCHS
3.1 Researches tendency
Investigation in adsorbing materials:
silica gel/water
● zeolite/water
● activated carbon
● activated carbon fibres/ammonia
● Methanol
● R134a
●
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3. RESEARCHS
3.1 Researches tendency
Adsorption refrigeration systems modelling:
Many modelling techniques;
● Simulate the adsorption refrigeration systems;
● Simulation techniques:
●
lumped-parameter ;
● lumped analytical ;
● dynamic ;
● distributed .
●
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3. RESEARCHS
3.1 Researches tendency
Simulation constant values:
Overall heat transfer coefficient for adsorbent
beds;
● Evaporator;
● Condenser.
●
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3. RESEARCHS
3.1 Researches tendency
Researches about adsorption cooling:
Divided into some specifics ways to improve adsorption
cooling systems.
evaluation of adsorption and physical-chemical
properties of the working-pairs;
● development of predictive models of their behaviour in
different working conditions.
● study of the different kinds of cycles.
●
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3. RESEARCHS
3.1 Researches tendency
Figura 5. Design drawing and a frontal view of the
adsorption chiler test facility.
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3. RESEARCHS
3.2 Read Researches
Development and test of two heat regenerative
adsorption systems:
●
ice making and air conditioning;
●
activated carbon-methanol adsorption pair;
●
cycle time was short → good heat transfer.
18/27
3. RESEARCHS
3.2 Read Researches
Synthesis and characterization of a new composite
sorbent:
Improve the adsorbent;
● Make the isobars of ads-/desorption steeper;
● Increase the mass of water exchanged at the same
boundary conditions;
● Improve the hydrothermal stability.
●
19/27
3. RESEARCHS
3.2 Read Researches
Testing of the lab scale adsorption chiller:
Study the influence of the cycle time;
● Study the relative duration of the isobaric steps;
● Relative duration of the isobaric steps on the
performance of an adsorption cooling system.
●
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3. RESEARCHS
3.2 Read Researches
Design and performance prediction of a new
generation adsorption chiller:
(Mathematical model)
● Describe
the heat and mass transfer process
● Adsorbent
bed
the composite adsorbent
● the metal of the tube
● the working fluids
●
● Condenser
cooling water
● the metal of the tube
● refrigerant
●
21/27
3. RESEARCHS
3.2 Read Researches
Optimization the operation strategy :
● Different temperatures of hot water inlet, cooling water
inlet and chilling water inlet → different COP and cooling
capacity;
● Conventional chiller;
● Composite adsorbent
higher cooling capacity
COP slightly higher
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4 . APLICATIONS
● Jiagsu Province, China
cool a grain depot during hot summers ;
● silica-gel adsorption chiller driven by a low
temperature heat source .
●
● Shanghai Research Institute of Building Science
●
chillers being used in the air conditioning system of a
“green” building.
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4 . APLICATIONS
(a)
(b)
Figure 6. (a) Shanghai ‘‘Green’’ Building; (b) equipment room.
24/27
4 . APLICATIONS
● European project Climasol
●
examples of buildings that already use solar-powered
sorption air conditioners
● System located in the cosmetic company
●
adsorption chillers powered by hot water in the
summer
● Chinese
● small
policy for energy exploitation
power adsorption chillers
● suitable for combined cooling, heating and power
systems or heating and power system
25/27
5 . CONCLUSIONS
We tried to synthesize the four articles, taking the best that
each had. It was observed that:
• Adsorption cooling systems are becoming increasingly
considered for applications where cooling is required and
low grade heat is available.
• Adsorption refrigerating machines consist essentially of an
evaporator, a condenser, valves, and an adsorber-reactor
containing a porous medium as adsorbent.
• Some parameters influence in the performance of the system
and there are drawbacks in these systems that don’t make
them so commercially attractive.
• Researches about adsorption cooling are divided into some
specifics ways to improve adsorption cooling systems.
• Looking for real application for the cooling adsorption, some
buildings and grain depot were found in Asia and Europe.
26/27
Thank you!
CHEMICAL ENGINEER
University of Valladolid
Chemical Engineering Laboratory II
CHILLING ADSORPTION
Ana Celina Gondim Santos
Sara Pérez Nieto
(Group B - 22)
Valladolid, 20 de Octubre de 2011