Thermoelectric Cooler Based Regenerative Adsorption Refrigeration System for High Temperature Electronics

2007 ◽  
Author(s):  
Ashish Sinha ◽  
Yogendra Joshi ◽  
Bruce H. Storm
Keyword(s):  
Coefficient Of Performance ◽  
Thermoelectric Cooler ◽  
Adsorption Refrigeration ◽  
Evaporator Temperature ◽  
Excess Heat ◽  
High Temperature Electronics ◽  
Bed Temperature ◽  
Heat Regeneration ◽  
A Tec ◽  
Adsorption Cycle

This paper presents the analytical study of a thermoelectric cooler (TEC) based two-stage regenerative adsorption cycle with evaporator temperature ranging from 80°C to 180°C and heat rejection temperature ranging from 200°C to 230°C. This proposed cycle restricts the highest temperature at which the TEC regenerates heat by reducing the maximum bed temperature during the desorption phase, which leads to the possibility of the system being realized with commercially available TECs and a reasonable TEC coefficient of performance (COP∼ 0.4). The low COP (<1) of the TEC results in excess heat at the desorption bed during heat regeneration. If the excess heat is rejected to the environment, COP gains arising from regeneration are reduced. Using the TEC to regenerate only part of the heat helps to mitigate this problem. The adsorption cycle in conjunction with TEC can pump heat through larger temperature differences with system efficiency much greater than that of a TEC used alone under identical conditions. The study aims to extend the limits of the adsorption refrigeration systems to provide compact cooling devices for harsh environments.

Performance of Thermoelectric Based Regenerative Adsorption Cooling System for Harsh Environment

2009 ◽  
Author(s):  
Ashish Sinha ◽  
Yogendra Joshi
Keyword(s):  
Heat Flow ◽  
Cycle Time ◽  
Cooling System ◽  
Fixed Time ◽  
Coefficient Of Performance ◽  
Thermoelectric Device ◽  
Harsh Environment ◽  
Evaporator Temperature ◽  
Heat Regeneration ◽  
Adsorption Cooling System

Performance of a cooling system designed for thermal management of harsh environment electronics has been presented. The system is based on regenerative adsorption-desorption cycle and mainly comprises of two beds with zeolite-water as adsorbent-adsorbate pair, a condenser and an evaporator. Heat regeneration was achieved by a thermoelectric (TE) device placed in between the zeolite beds. Use of a thermoelectric device for heat transfer in between beds allows for miniaturization of usually bulky adsorption cooling systems. This also provides a cooling system with nearly no moving parts, hence suitable for harsh environment electronic cooling applications. Zeolite beds alternately carry out adsorption and desorption depending on the direction of heat flow in between them. Direction of heat flow is governed by the polarity of voltage applied across the TE device. Polarity is switched at fixed time intervals that determine the cycle time. Tests were carried out during which the condenser temperature hovered around 165 °C, heat load was up to 5W, the cycle time kept close to 12 minutes and the targeted evaporator temperature was 140 °C. System was analyzed in terms of the extent of cooling below the heat rejection ambient temperature of 160 °C and coefficient of performance. A COP of 0.2 was obtained. The study could be used to extend the working envelopes of existing electronics towards hotter surroundings. A mathematical model was also prepared and the experimental results have been compared with the simulations.

Performance Analysis of a Cascading Adsorption Cycle Powered by High-Temperature Heat Sources for Low-Temperature Cooling in Hot Climates

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Dalila Abbaz ◽  
Abla Chaker ◽  
Mahmoud Bourouis
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Thermal Conditions ◽  
Coefficient Of Performance ◽  
Large Temperature ◽  
Heat Sources ◽  
Adsorption Refrigeration ◽  
Temperature Heat ◽  
Adsorption Cycle

Abstract Cascade adsorption refrigeration technology using high-temperature driving heat is a very promising option for low-temperature cooling applications due to the large temperature difference between the heat source and the cold distributed. The present work carried out a feasibility and parametric study in order to analyze the functioning of a cascading adsorption cycle using the working pair zeolite/ammonia in beds operating at high temperatures and activated carbon/ammonia in those operating at low temperatures. At the nominal thermal conditions, namely, heating, condensing, and evaporating temperatures of 280 °C, 35 °C, and (−5) °C, respectively, the coefficient of performance (COP) and the specific refrigerating capacity (SCP) of the cycle were 0.53 and 67.1 W/kg. When the driving temperature is varied from 260 °C to 320 °C, the COP increases by 57% and the SCP by 36%. The performance of the cascading adsorption cycle at negative evaporating temperatures is very satisfactory.

scholarly journals Performance Analysis of an Adsorption Refrigeration System Working on Activated Carbon/Methanol Pair Using Finned Tube Type Adsorber Bed

2021 ◽  
Vol 39 (4) ◽  
pp. 1335-1342
Author(s):  
Palash Soni ◽  
Sruthi Lolalis ◽  
Bidyut Mazumdar ◽  
Shubhankar Bhowmick ◽  
Vivek Kumar Gaba
Keyword(s):  
Activated Carbon ◽  
Finned Tube ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Adsorption Refrigeration ◽  
Evaporator Temperature ◽  
Tube Type ◽  
Finite Difference Discretization ◽  
The Mathematical Model ◽  
Difference Discretization

Adsorption refrigeration, being a unique and eco-friendly technology, has gained popularity over conventional refrigeration systems. The present study is aimed at developing an annular finned tube adsorber model which serves as a thermal compressor in adsorption refrigeration systems. The mathematical model is addressed numerically using finite difference discretization method and explicit scheme was used for the solution. The generalized model has been simulated for activated carbon–methanol working pair. The system has an optimum cycle time of 1800s. It was found to have a highest refrigeration capacity of 260.66 kJ/kg at a regeneration temperature of 393 K and evaporator temperature of 283 K. The highest COP (Coefficient of Performance) achieved by the system is 0.3706 at a regeneration temperature of 353 K and evaporator temperature of 283 K. A highest SCP (Specific Cooling Power) of 144.8 W/kg was obtained at an evaporator temperature of 283 K and regeneration temperature of 393 K.

Thermodynamic analysis of triple effect ammonia–water absorption compression (hybrid) cycle

2021 ◽  
pp. 095440892199568
Author(s):  
CP Jawahar
Keyword(s):  
Water Absorption ◽  
Energy Analysis ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Performance Parameters ◽  
Evaporator Temperature ◽  
Ammonia Water ◽  
Absorption Cycle ◽  
Hybrid Cycle

This paper presents the energy analysis of a triple effect absorption compression (hybrid) cycle employing ammonia water as working fluid. The performance parameters such as cooling capacity and coefficient of performance of the hybrid cycle is analyzed by varying the temperature of evaporator from −10 °C to 10 °C, absorber and condenser temperatures in first stage from 25 °C to 45 °C, degassing width in both the stages from 0.02 to 0.12 and is compared with the conventional triple effect absorption cycle. The results of the analysis show that the maximum cooling capacity attained in the hybrid cycle is 472.3 kW, at 10 °C evaporator temperature and first stage degassing width of 0.12. The coefficient of performance of the hybrid cycle is about 30 to 65% more than the coefficient of performance of conventional triple effect cycle.

Performance Characteristics of a Combined Ejector-Absorption Heat Pump Using NH3-H2O

1999 ◽  
Author(s):  
D. A. Kouremenos ◽  
E. D. Rogdakis ◽  
G. K. Alexis
Keyword(s):  
Heat Pump ◽  
Gain Factor ◽  
Coefficient Of Performance ◽  
Detailed Calculation ◽  
Absorption System ◽  
Evaporator Temperature ◽  
Pump System ◽  
Heat Gain ◽  
Absorption Heat Pump ◽  
Heat Pump System

Abstract Absorption system have been investigated for many years. However, coefficient of performance COP or heat gain factor HGF for absorption systems are significantly lower than those for conventional compression systems. This has restricted their wide application. This paper discusses the behavior of mixture NH3-H2O through of an ejector, operating in an absorption heat pump system. This combination improves the performance of conventional absorption system and with the phasing out of ozone-damaging refrigerants, absorption refrigerators, heat pumps and air-conditioning now provide a potential alternative. For the detailed calculation of the proposed system a method has been developed, which employs analytical functions describing the thermodynamic properties of die mixture. The influence of three major parameters: generator, condenser and evaporator temperature, on ejector efficiency and heat gain factor of the system is discussed. Also the maximum value of HGF was estimated by correlation of above three temperatures.

Three-Dimensional Analysis on the Performance of the Thermoelectric Micro-Cooler

2005 ◽  
Author(s):  
Kong Hoon Lee ◽  
Ook Joong Kim
Keyword(s):  
Temperature Difference ◽  
Three Dimensional ◽  
Coefficient Of Performance ◽  
Thermoelectric Cooler ◽  
Small Temperature ◽  
Small Current ◽  
Thermoelectric Element ◽  
Maximum Value ◽  
Column Type ◽  
P Type

Three-dimensional numerical analysis has been carried out using the FEMLAB software package to figure out the performance of the thermoelectric micro-cooler. A small-size and column-type thermoelectric cooler is considered and Bi2Te3 and Sb2Te3 are selected as the n- and p-type thermoelectric materials, respectively. The thickness of the thermoelectric element considered is 5 to 20 μm and the thickness affects the performance of the cooler. The effect of parameters such as the temperature difference, the current, and the thickness of the thermoelectric element on the performance of the cooler has also been investigated. The coefficient of performance (COP) is the primary factor to evaluate the performance of the cooler and the COP varies with the parameters. The COP has the maximum value at a certain current and the value decreases with the temperature difference or the thickness. The predicted results also show that the performance can be improved for thick thermoelectric element at the small temperature difference and small current.

scholarly journals Calculation algorithm for operating parameters of steam-compressive chilling machine with adsorptive chillling unit

2020 ◽  
Vol 8 (2) ◽  
pp. 3-9
Author(s):  
E.A. Belyanovskaya ◽  
◽  
G.M. Pustovoy ◽  
A.I. Sklyarenko ◽  
M.P. Sukhyy ◽  
...  
Keyword(s):  
Silica Gel ◽  
Thermal Energy ◽  
Sodium Acetate ◽  
Operating Conditions ◽  
Energy Utilization ◽  
Coefficient Of Performance ◽  
Adsorptive Capacity ◽  
Operating Parameters ◽  
Adsorption Refrigeration ◽  
Refrigeration Unit

The work is focused on the development of an effective algorithm for calculating the operational characteristics of a steamcompressive chilling machine with an adsorptive chilling unit, which involves a cold box, an adsorber, an evaporator and a condenser, water being used as a refrigerant. An algorithm for calculating the operating parameters of the adsorptive chilling unit has been developed, which includes the determination of the cooling capacity of the steam compressor refrigeration unit, the heat load on the condenser, the power consumed by the compressor, the coefficient of performance of the steam compressor refrigeration unit, as well as the calculation of the mass of water, the mass of the adsorbent, the refrigerating capacity, the coefficient of performance of the adsorptive chilling unit and the coefficient of useful energy utilization of a steam compressive chilling machine with an adsorption chilling unit. The chilling capacity and the coefficient of performance of the adsorption chilling unit are estimated under the operating conditions of a typical steam compression chilling machine. The crucial factors affecting the efficiency of the adsorptive chilling unit are analyzed. It has been established that the chilling capacity, the coefficient of performance of the adsorption refrigeration module and the energy efficiency of the installation are determined by the thermal load on the condenser, and, therefore, by the mass of water that is desorbed and evaporated. The coefficient of performance of the adsorption chilling unit and the efficiency of the steam compressor chilling machine with the adsorptive chilling unit are estimated to be 0.878 and 4.64. The criteria for the selection of adsorbents for the adsorption module are analyzed. The temperature of regeneration is determined by the temperatures in the condenser, and the limit adsorption affects the mass of the adsorbent and the size of the adsorber. A comparison of the efficiency of adsorptive chi l l ing uni t based on silicoaluminophosphates and composite adsorbents «silica gel – sodium acetate» is carried out. The prospects of using composites «silica gel – СН3СООNa» are shown. The optimal composition of the composite was established, which corresponds to the minimal size of the adsorber, (80% sodium acetate and 20% silica gel). The prospects of using adsorptive conversion of thermal energy for utilization of low-potential thermal energy during the operation of steam compressive chilling machine are shown. Keywords: adsorptive conversion of heat energy, composite adsorbent, steam compressive chilling unit, adsorption, adsorptive capacity.

Optimized Refrigerant Flow Rate and Dimensions of the Ejector Employed in a Modified Ejector Vapor Compression System

2020 ◽  
Vol 28 (04) ◽  
pp. 2050038
Author(s):  
Dishant Sharma ◽  
Gulshan Sachdeva ◽  
Dinesh Kumar Saini
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Evaporator Temperature ◽  
Proposed Model ◽  
Condenser Temperature ◽  
Vapor Compression System ◽  
Vapor Compression Cooling

This paper presents the analysis of a modified vapor compression cooling system which uses an ejector as an expansion device. Expanding refrigerant in an ejector enhances the refrigeration effect and reduces compressor work. Therefore, it yields a better coefficient of performance. Thermodynamic analysis of a constant area ejector model has been done to obtain primary dimensions of the ejector for given condenser and evaporator temperature and cooling capacity. The proposed model has been used to design the ejector for three refrigerants; R134a, R152a and R1234yf. The refrigerant flow rate and the diameters at various sections of the ejector have been obtained by doing numerical modeling in Engineering Equation Solver (EES). Refrigerant R1234yf demanded the highest diameter requirements at a fixed 5∘C evaporator temperature and 40∘C condenser temperature for a given range of cooling load. Both primary and secondary refrigerants flow rates are higher for R1234yf followed by R134a and then R152a.

Experimental Investigation of Ejector-Assisted Vapor Compression System

2019 ◽  
Vol 27 (03) ◽  
pp. 1950029
Author(s):  
Vikas Kumar ◽  
Gulshan Sachdeva
Keyword(s):  
Capillary Tube ◽  
Area Ratio ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Evaporator Temperature ◽  
Compression System ◽  
Wide Range ◽  
Expansion Valve ◽  
Maximum Improvement ◽  
Vapor Compression System

The performance of an ejector as an expansion device rather than the conventional expansion valve or capillary tube in a vapor compression system is experimentally analyzed. Experiments have been conducted using 28 ejectors of different dimensions at the same condenser and evaporator temperatures, and it has been observed that for utmost performance, an optimum area ratio of the ejector is required. One of the ejector geometry has been experimented further for a wide range of condenser and evaporator temperatures. The coefficient of performance is found to be enhanced by at least 10% in comparison to the conventional vapor compression system for the considered range of condenser and evaporator temperatures and the maximum improvement in COP obtained is 12.83% at 14.3∘C evaporator temperature and 32.4∘C condenser temperature with 17.9211 ejector area ratio. The refrigerant R134a has been used as the working substance.

Study on Single- and Multi-Stage Adsorption Cooling Cycles Working at Sub and Above Atmospheric Conditions

2008 ◽  
Author(s):  
Bidyut B. Saha ◽  
Ibrahim I. El-Sharkawy ◽  
Anutosh Chakraborty ◽  
Shigeru Koyama ◽  
Kim Choon Ng
Keyword(s):  
Activated Carbon ◽  
Atmospheric Pressure ◽  
Activated Carbon Fiber ◽  
Coefficient Of Performance ◽  
Atmospheric Conditions ◽  
Surface Cooling ◽  
Multi Stage ◽  
Theoretical Results ◽  
Partial Vacuum ◽  
Adsorption Cycle

This study deals with the performance analysis of single- and multi-stage adsorption cooling cycles working at partial vacuum and pressurized conditions for cooling applications. Four adsorbent-refrigerant pairs namely activated carbon fiber-ethanol, silica gel-water, Maxsorb II-R134a and Fluka-R134a pairs have been investigated. The former two pairs are deemed to be suitable for adsorption cycles working at pressures ranging from 1 to 11 kPa while the latter two are suitable for those working at above atmospheric pressure conditions typically between about 0.3 and 0.8 MPa. Invoking the adsorption isotherms of the assorted pairs, the pressure-temperature-concentration (P-T-W) diagrams have been presented. Pertaining a thermodynamic framework, the performance of both single- and multi-stage cycles in terms of specific cooling effect (SCE) and coefficient of performance (COP) has also been studied. Theoretical results show that the former two pairs i.e., the adsorption cycles working at partial vacuum pressures are suitable for surface cooling while latter two are suitable for micro cooling applications. Moreover, the multi-stage adsorption cycles can be operational at a heat source temperature below about 55°C, a region that could not be reached by any conventional adsorption cycle.

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