scholarly journals Improving the Energy Efficiency of Adsorption Chillers by Intensifying Thermal Management Systems in Sorbent Beds

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Brian K. Paul ◽  
Kijoon Lee ◽  
Hailei Wang
Keyword(s):  
Thermal Management ◽  
Heat Exchangers ◽  
System Performance ◽  
Thermal Model ◽  
Coefficient Of Performance ◽  
Management Systems ◽  
Cooling Power ◽  
Thermal Mass ◽  
Adsorption Refrigeration ◽  
Microchannel Heat Exchanger

The objective of this study was to develop a strategy for miniaturizing heat exchangers (HXs) used for the thermal management of sorbent beds within adsorption refrigeration systems. The thermal mass of the microchannel heat exchanger (MCHX) designed and fabricated in this study is compared with that of commercially available tube-and-fin HXs. Efforts are made to quantify the overall effects of miniaturization on system coefficient of performance (COP) and specific cooling power (SCP). A thermal model for predicting the cycle time for desorption is developed, and experiments are used to quantify the effect of the intensified HX on overall system performance.

Improving the Energy Efficiency of Adsorption Chillers by Intensifying Thermal Management Systems in Sorbent Beds

2017 ◽  
Author(s):  
Brian K. Paul ◽  
Kijoon Lee ◽  
Hailei Wang
Keyword(s):  
Heat Exchanger ◽  
Thermal Management ◽  
Heat Exchangers ◽  
Thermal Model ◽  
Coefficient Of Performance ◽  
Management Systems ◽  
Cooling Power ◽  
Thermal Mass ◽  
Adsorption Refrigeration ◽  
Microchannel Heat Exchanger

The objective of this study was to develop a strategy for miniaturizing heat exchangers used for the thermal management of sorbent beds within adsorption refrigeration systems. The thermal mass of the microchannel heat exchanger designed and fabricated in this study is compared with that of commercially available tube-and-fin heat exchangers. Efforts are made to quantify the overall effects of miniaturization on system coefficient of performance and specific cooling power. A thermal model for predicting the cycle time for desorption is developed and experiments are used to quantify the effect of the intensified heat exchanger on overall system performance.

Performance Investigation of Single Adsorption Refrigeration System Driven by Solar Heat Storage

2018 ◽  
Vol 26 (03) ◽  
pp. 1850025
Author(s):  
Hicham Boushaba ◽  
Abdelaziz Mimet
Keyword(s):  
System Performance ◽  
Heat Storage ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Solar Irradiation ◽  
Cooling Power ◽  
Condensation Temperature ◽  
Adsorption Refrigeration ◽  
Solar Heat

The aim of this paper is to provide a global study of an adsorption refrigeration machine driven by solar heat storage and collected by parabolic trough collector. The system operates with ammonia (as refrigerant) and activated carbon (as adsorbent). A mathematical model interpreting the progression of the heat and the mass transfer at each element of the prototype has been developed. The solar irradiation and the real ambient temperature variations corresponding to a usual summer day in Tetouan (Morocco) are considered. The system performance is evaluated trough specific cooling power (SCP) as well as solar coefficient of performance (SCOP), which was estimated by a dynamic simulation cycle. The pressure, temperature and adsorbed mass profiles in the Adsorber have been calculated. The effects of significant design and operating parameters on the system performance have been investigated. The results show the capability of our system to realize an encouraging performance and to overcome the intermittence of the adsorption refrigeration machines. For a daily solar irradiation of 18[Formula: see text]MJ[Formula: see text]m[Formula: see text] and operating conditions of evaporation temperature [Formula: see text]C, condensation temperature [Formula: see text]C and generation temperature [Formula: see text]C, the results show that the process could achieve an SCP of 115[Formula: see text]W[Formula: see text]kg[Formula: see text] and it could produce a daily specific cooling capacity of 3310[Formula: see text]kJ[Formula: see text]kg[Formula: see text], whereas its SCOP could attain 0.141.

Modeling of a Refrigerator in Disaster Vehicle, Using Solar Energy and Engine Exhaust Gases Heat

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Shahram Derakhshan ◽  
Alireza Yazdani
Keyword(s):  
Solar Energy ◽  
Electrical Energy ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Refrigeration Cycle ◽  
Adsorption Refrigeration ◽  
Engine Exhaust ◽  
Exhaust Gases ◽  
Exhaust Heat ◽  
Heat Adsorption

In critical situations such as floods and earthquakes, the relief forces require a refrigeration for pharmaceuticals and vaccines, which could operate without an electrical energy and the alternative energies, such as solar energy, engine exhaust gases heat, and wind energy. In this paper, a refrigeration cycle has been modeled as an adsorption refrigeration cycle with an activated carbon/methanol as adsorbent/adsorbate pair and two sources of energy—solar energy and engine exhaust gases heat. The solar cycle had a collector with area of 1 m2 and the exhaust gas cycle included a heat exchanger with 100 °C temperature difference between inlet and outlet gases. The temperature profile in adsorbent bed, evaporator, and condenser was obtained from modeling. Moreover, the pressure profile, overall heat transfer coefficient of collector and adsorbent bed, concentration, and the solar radiation were reported. Results represented the coefficient of performance (COP) of 0.55, 0.2, and 0.56 for complete system, solar adsorption refrigeration, and exhaust heat adsorption refrigeration, respectively. In addition, exhaust heat adsorption refrigeration has a value of 2.48 of specific cooling power (SCP). These results bring out a good performance of the proposed model in the climate of Iran.

scholarly journals Performance Prediction of Solar Adsorption Refrigeration System by Ann

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
V. Baiju ◽  
C. Muraleedharan
Keyword(s):  
Neural Network ◽  
Performance Prediction ◽  
Conjugate Gradient ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Performance Parameters ◽  
Refrigeration System ◽  
Back Propagation Algorithm ◽  
Adsorption Refrigeration ◽  
Discharge Temperature

This paper proposes a new approach for the performance analysis of a single-stage solar adsorption refrigeration system with activated carbon-R134a as working pair. Use of artificial neural network has been proposed to determine the performance parameters of the system, namely, coefficient of performance, specific cooling power, adsorbent bed (thermal compressor) discharge temperature, and solar cooling coefficient of performance. The ANN used in the performance prediction was made in MATLAB (version 7.8) environment using neural network tool box.In this study the temperature, pressure, and solar insolation are used in input layer. The back propagation algorithm with three different variants namely Scaled conjugate gradient, Pola-Ribiere conjugate gradient, and Levenberg-Marquardt (LM) and logistic sigmoid transfer function were used, so that the best approach could be found. After training, it was found that LM algorithm with 9 neurons is most suitable for modeling solar adsorption refrigeration system. The ANN predictions of performance parameters agree well with experimental values with R2 values close to 1 and maximum percentage of error less than 5%. The RMS and covariance values are also found to be within the acceptable limits.

Simulation Study of the Heat and Mass Recovery on the Performance of Adsorption Cooling Systems

2014 ◽  
Author(s):  
K. C. Chan ◽  
C. Y. Tso ◽  
Christopher Y. H. Chao
Keyword(s):  
System Performance ◽  
Heat Recovery ◽  
Cooling System ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Cooling Systems ◽  
Heating And Cooling ◽  
Adsorption Cooling System ◽  
Heat And Mass Recovery ◽  
Mass Recovery

In this study, simulation was conducted to investigate the effect of mass recovery, heat recovery, pre-heating and pre-cooling time on the system performance of a double-bed adsorption cooling system. Pressures of different system components were considered in the simulation. The adsorbent-adsorbate pair used was silica-gel and water. The heating and cooling temperatures were selected to be 85°C and 27°C respectively. Both the adsorption and desorption phase times were set at 15 minutes. The coefficient of performance (COP) and specific cooling power (SCP) were used to quantify the performance of the system. From the simulation, the basic cycle provided COP and SCP of 0.20 and 40.9W/kg respectively. By conducting heat recovery for 120 seconds, the system COP was largely increased by 99% to 0.40 compared to the basic cycle. The SCP was also increased to 42.3W/kg. Mass recovery, however, did not have too much effect on the system performance. The COP and SCP only increased by 4.5% and 3.9% respectively when conducting mass recovery for 4.7 seconds. For conducting heat and mass recovery, the COP and SCP were increased to 0.36 and 44.68W/kg, respectively. Pre-heating and pre-cooling can also be beneficial in improving both COP and SCP. The COP and SCP were increased by 14.5% and 10.1% respectively, to 0.23 and 45.0W/kg by conducting pre-heating and pre-cooling for 50.3 seconds. The combinations of these processes were also studied. It is suggested heat and mass recovery then pre-heating and pre-cooling should be conducted to improve COP and SCP. The improvements showed 31.2% for COP, increasing to 0.27, and 11.9% for SCP, increasing to 45.7W/kg.

scholarly journals Performance evaluation of an adsorption refrigeration system powered by solar heat storage based on Moroccan irradiation

2020 ◽  
Vol 307 ◽  
pp. 01014
Author(s):  
Hicham BOUSHABA ◽  
Abdelaziz MIMET ◽  
Mohammed El GANAOUI ◽  
Abderrahman MOURADI
Keyword(s):  
Heat Storage ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Solar Irradiation ◽  
Cooling Power ◽  
Condensation Temperature ◽  
Refrigeration System ◽  
Adsorption Refrigeration ◽  
The Real ◽  
Solar Heat

The aim of this paperwork is to provide a performance comparative study of an adsorption refrigeration system powered by solar heat storage based on Moroccan irradiation. The system operates with ammonia as refrigerant and activated carbon as adsorbent. A parabolic through collector is used to collect the solar energy and store it in a heat storage tank. A dynamic simulation program interpreting the real behavior of the system has been developed. The pressure, temperature and adsorbed mass profiles in the Adsorber have been revealed. The system performance is estimated in terms of the specific cooling power (SCP) and the solar coefficient of performance (SCOP). The solar irradiation and the real ambient temperature variations corresponding to the six climatic zones in Morocco are considered. The effect of those conditions on the performance of the system has been investigated. The results show the capability of our system to realize more than one cycle and produce cold during the day. For an optimal configuration of the system and operating conditions of evaporation temperature, Tev=0 °C, condensation temperature, Tcon=30 °C and generation temperature, T3=100 °C, the process could achieve a SCP of 151 W.kg-1and its solar COP could attain 0.148. The system performances improve especially in sunny area.

Reviews of Studying on Thermal Management System in EV/HEV Battery Pack

2011 ◽  
Vol 291-294 ◽  
pp. 1674-1678 ◽  
Author(s):  
Zhen Po Wang ◽  
Chun Lu ◽  
Peng Liu
Keyword(s):  
Temperature Field ◽  
Thermal Management ◽  
Management System ◽  
Battery Pack ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Closed Cycle ◽  
Safe Operation ◽  
Thermal Management System ◽  
Battery Packs

Keeping appropriate temperature of battery pack is crucial for EV/HEV’s safe operation and optimal performance. Existing literatures mainly concerned theoretical analysis on comparison of different cooling/heating methods and distribution of temperature field in a battery pack. This paper reviewes recent research about design, test and optimization of thermal management system, and presents a prediction of development. Further research should focus on coefficient-of-performance (COP) analysis, closed-cycle control of heating/cooling power, optimizing the theoretical designs and testing more battery packs.

scholarly journals Adsorbents, Working Pairs and Coated Beds for Natural Refrigerants in Adsorption Chillers—State of the Art

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4707
Author(s):  
Piotr Boruta ◽  
Tomasz Bujok ◽  
Łukasz Mika ◽  
Karol Sztekler
Keyword(s):  
Cooling System ◽  
Fundamental Problem ◽  
Thermodynamic Cycle ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Adsorption Refrigeration ◽  
Cooling Systems ◽  
Sustainable Solutions ◽  
Improved Performance

Adsorption refrigeration systems are promising, sustainable solutions for many cooling applications. The operating range and the performance of an adsorption cooling cycle are strongly dependent on the properties of adsorbents, adsorbates, and bed coatings. Therefore, further research and analysis may lead to improved performance of adsorption coolers. In this paper, studies on working pairs using natural refrigerants and the properties of adsorbent coatings were reviewed. The selected working pairs were then thermodynamically characterised and ranked in terms of refrigerant evaporation temperature values. This was found to be a key parameter affecting the applicability of a given adsorbent/adsorbate pair and the value of SCP (Specific Cooling Power), COP (Coefficient of Performance) parameters, which are now commonly used comparison criteria of adsorption chillers. In the analysis of the coating studies, the focus was on the effect of individual parameters on the performance of the cooling system and the effect of using coated beds compared to packed beds. It was found that a fundamental problem in comparing the performance of different cooling systems is the use of different operating conditions during the tests. Therefore, the analysis compares the performance of the systems along with the most important thermodynamic cycle parameters for the latest studies.

scholarly journals Simultaneous Optimization of Process Operational and Material Parameters for a 2-Bed Adsorption Refrigeration Process

2020 ◽  
Vol 4 (2) ◽  
pp. 31
Author(s):  
Marc Scherle ◽  
Ulrich Nieken
Keyword(s):  
Structural Material ◽  
Material Model ◽  
Heat Pumps ◽  
Simultaneous Optimization ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Operational Parameters ◽  
Adsorption Refrigeration ◽  
Adsorption Chiller ◽  
Material Parameters

In process engineering, optimization is usually carried out without the simultaneous consideration of material and process. This issue is addressed in the following contribution. A model-based optimization is presented to improve the performance of adsorption heat pumps. Optimization is carried out in two steps. First, we optimize the operational parameters, the cycle time, and the thickness of the adsorbent for a given adsorption material. In a second step we use a material model to predict heat and mass transfer and adsorption capacity from structural material parameters. This allows us to vary the structural material parameters and calculate the optimal operational parameters for each adsorbent. The two-step optimization thus identifies optimal material properties together with corresponding optimal operational parameters. As constraints, a minimum specific cooling power (SCP) and the passive mass of heat transfer pipes are used. The coefficient of performance (COP) is taken as the objective function. We exemplarily demonstrate the approach for a two-bed adsorption chiller, carbide-derived carbon as the adsorbent, methanol as the sorptive and boron-nitrate as additive to improve heat conductivity. The approach can be easily extended to multi-bed installations and more sophisticated material models.

Aerodynamic and Thermal Measurements in a Standing Wave Thermoacoustic Refrigerator

2010 ◽  
Author(s):  
Gaelle Poignand ◽  
Emmanuel Jondeau ◽  
Philippe Blanc-Benon
Keyword(s):  
Heat Transfer ◽  
Standing Wave ◽  
Heat Exchangers ◽  
System Performance ◽  
Heat Fluxes ◽  
Acoustic Energy ◽  
Working Fluid ◽  
Cooling Power ◽  
Thermal Measurements ◽  
Thermoacoustic Refrigerator

Thermoacoustic refrigerators produce a cooling power from an acoustic energy. Over the last decades, these devices have been extensively studied since they are environment-friendly, robust and miniaturizable. Despite all these advantages, their commercialization is limited by their low efficiency. One reason for this limitation comes from the complex thermo-fluid process between the stack and the two heat exchangers which is still not sufficiently understood to allow for optimization. In particular, at high acoustic pressure level, vortex shedding can occur behind the stack as highlight by [Berson & al., Heat Mass Trans, 44, 10151023 (2008)]. The created vortex can affect heat transfer between the stack and the heat exchangers and thus, they can reduce the system performance. In this work, aerodynamic and thermal measurements are both conducted in a standing wave thermoacoustic refrigerator allowing investigation of vortex influence on the system performance. The proposed device consists on a resonator operated at frequency of 200 Hz, with hot and cold heat exchangers placed at the stack extremities. The working fluid is air at ambient temperature and atmospheric pressure. The aerodynamic field behind the stack is described using high-speed Particle Image Velocimetry. This technique allows the acoustic velocity field measurement at a frequency up to 3000 Hz. Thermal measurements consist on the acquisition of both the temperature evolution along the stack and the heat fluxes extracted at the cold heat exchanger. These measurements are performed by specific micro-sensors developed by MEMS technology. The combination of these two measurements should be helpful for the further understanding of the heat transfer between the stack and the heat exchangers.

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