Modeling a Novel Composite Adsorbent Based Adsorption Chiller Driven by Solar Energy

2013 ◽  
Author(s):  
C. Y. Tso ◽  
S. C. Fu ◽  
Christopher Y. H. Chao
Keyword(s):  
Coefficient Of Performance ◽  
Seasonal Effects ◽  
Cooling Power ◽  
Insulation Material ◽  
Composite Adsorbent ◽  
Adsorption Chiller ◽  
Flat Type ◽  
Collector Temperature ◽  
Typical Summer ◽  
Solar Powered

This paper aims to study the performance of a solar-powered adsorption chiller with a novel composite adsorbent material (silica activated carbon/CaCl2) operating during some typical months in Hong Kong. Modeling is established to investigate the cooling performance of this adsorption chiller driven by flat-type solar collectors with three different configurations of glaze: 1) single glazed cover; 2) double glazed cover and 3) transparent insulation material (TIM) cover. The simulation results show that the higher the solar collector temperature is, the better the coefficient of performance (COP) and the specific cooling power (SCP) of the adsorption chiller are. It is suggested to select a double glazed collector with a small value of the lumped capacitance for this adsorption chiller. Seasonal effects are discussed in which the solar COP achieves its highest value during autumn. However, the cooling capacities in spring, summer and autumn are similar. All in all, this newly developed composite material as adsorbent used in the adsorption chiller could achieve a mean solar COP of 0.36 and SCP of 94W/kg on a typical summer day of operation.

scholarly journals Absorption and adsorption chillers applied to air conditioning systems

2010 ◽  
Vol 31 (2) ◽  
pp. 77-94 ◽  
Author(s):  
Agnieszka Kuczyńska ◽  
Władysław Szaflik
Keyword(s):  
Heat Source ◽  
Air Conditioning ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Geothermal Heat ◽  
Pump System ◽  
Desorption Process ◽  
Heat Pump System ◽  
Adsorption Chiller ◽  
Air Conditioning Systems

Absorption and adsorption chillers applied to air conditioning systemsThis work presents an application possibility of sorption refrigerators driven by low temperature fluid for air conditioning of buildings. Thermodynamic models were formulated and absorption LiBr-water chiller with 10 kW cooling power as well as adsorption chiller with silica gel bed were investigated. Both of them are using water for desorption process with temperatureTdes= 80 °C. Coefficient of performance (COP) for both cooling cycles was analyzed in the same conditions of the driving heat source, cooling waterTc= 25 °C and temperature in evaporatorTevap= 5 °C. In this study, the computer software EES was used to investigate the performance of absorption heat pump system and its behaviour in configuration with geothermal heat source.

scholarly journals Performance Results of a Solar Adsorption Cooling and Heating Unit

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1630 ◽  
Author(s):  
Tryfon C. Roumpedakis ◽  
Salvatore Vasta ◽  
Alessio Sapienza ◽  
George Kallis ◽  
Sotirios Karellas ◽  
...  
Keyword(s):  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Solar Thermal Energy ◽  
Cooling Mode ◽  
Heating Unit ◽  
Adsorption Chiller ◽  
Maximum Coefficient ◽  
Solar Powered ◽  
Evacuated Tube Collectors ◽  
Performance Results

The high environmental impact of conventional methods of cooling and heating increased the need for renewable energy deployment for covering thermal loads. Toward that direction, the proposed system aims at offering an efficient solar powered alternative, coupling a zeolite–water adsorption chiller with a conventional vapor compression cycle. The system is designed to operate under intermittent heat supply of low-temperature solar thermal energy (<90 °C) provided by evacuated tube collectors. A prototype was developed and tested in cooling mode operation. The results from the testing of separate components showed that the adsorption chiller was operating efficiently, achieving a maximum coefficient of performance (COP) of 0.65. With respect to the combined performance of the system, evaluated on a typical week of summer in Athens, the maximum reported COP was approximately 0.575, mainly due to the lower driving temperatures with a range of 75 °C. The corresponding mean energy efficiency ratio (EER) obtained was 5.8.

scholarly journals Effect of Metal Additives in the Bed on the Performance Parameters of an Adsorption Chiller with Desalination Function

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7226
Author(s):  
Karol Sztekler ◽  
Wojciech Kalawa ◽  
Łukasz Mika ◽  
Marcin Sowa
Keyword(s):  
Silica Gel ◽  
Electricity Consumption ◽  
Sorption Kinetics ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Adsorption Chiller ◽  
Cycle Times ◽  
Metal Additives ◽  
Low Performance ◽  
Kinetics Of

Adsorption chillers with desalination functionality, being devices characterised by very low electricity consumption, provide an alternative to conventional sources of cooling and water. The option of desalinating water means that the use of a single device enables obtaining two useful products. Adsorption chillers are not widely used at present. due to their low performance characteristics; these are, however, constantly being improved. This paper presents a verification of the possibility of increasing the cooling coefficient of performance (COP) and specific cooling power (SCP) of a laboratory adsorption chiller by optimising the length of cycle times and using a copper additive to silica gel with a mass fraction of 15% to increase heat transport in the bed. The choice of copper among other considered additives was determined by the conclusions from the research on the sorption kinetics of various mixtures, price and availability, and a high thermal conductivity. The device was operated in a two-bed mode aimed at producing cooling. The adsorbate was distilled water. The results were compared with those obtained under similar conditions when the beds were only filled with silica gel. As a result of the testing, it was found that the use of the copper additive with the sorbent increased both the COP and SCP. The tests were performed for different cycle times, of 100, 200, 300 and 600 s. With increasing cycle time COP also increased. In contrast, the specific cooling power increased only up to a certain point, whereafter its value decreased.

scholarly journals Experimental and Theoretical Study of the Energy Flow of a Two Stages Four Generators Adsorption Chiller

2019 ◽  
Vol 14 (2) ◽  
pp. 129-136
Author(s):  
Faeza Mahdi Hadi
Keyword(s):  
Activated Carbon ◽  
Cold Water ◽  
Water Cycle ◽  
Electrical Power ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Low Grade ◽  
Adsorption Chiller ◽  
Two Stages

This work is concerned with a two stages four beds adsorption chiller utilizing activated carbon-methanol adsorption pair that operates on six separated processes. The four beds that act as thermal compressors are powered by a low grade thermal energy in the form of hot water at a temperature range of 65 to 83 °C.  As well as, the water pumps and control cycle consume insignificant electrical power. This adsorption chiller consists of three water cycles. The first water cycle is the driven hot water cycle. The second cycle is the cold water cycle to cool the carbon, which adsorbs the methanol. Finally, the chilled water cycle that is used to overcome the building load. The theoretical results showed that average cycle cooling power is 2.15kW, while the experimental measurement revealed that the cooling capacity of the cycle is about 1.98 kW with a relative error of % 0.02. The generator and condensing temperatures are 83 and 30 °C, respectively. The coefficient of performance (COP) of that chiller was in the range of 0.37 to 0.49. The best operating point and the best working conditions were also investigated. The present chiller is superior more than the single stage, two beds adsorption chiller that works on the activated carbon methanol pair that needs a high ambient temperature.

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.

scholarly journals Experimental Study on Heat Transfer and Adsorption Cooling Performance of MIL-101/Few Layer Graphene Composite

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4970
Author(s):  
Yu Yin ◽  
Junpeng Shao ◽  
Lin Zhang ◽  
Qun Cui ◽  
Haiyan Wang
Keyword(s):  
Heat Transfer ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Cyclic Stability ◽  
Cooling Performance ◽  
Adsorption Chiller ◽  
Layer Graphene ◽  
Conductive Additive ◽  
Few Layer Graphene ◽  
Adsorption Desorption

MIL-101 is a promising metal-organic frameworks (MOFs) material in adsorption chiller application due to its high adsorption capacity for water and excellent adsorption/desorption cyclic stability. Few layer graphene (FLG) as the thermal conductive additive was added into MIL-101 to improve inferior heat transfer of MIL-101 in the adsorption cooling process. The heat transfer characteristic of MIL-101/FLG adsorber and the adsorption cooling performance of the MIL-101/FLG-water working pair were studied. Results show that thermal conductivity of MIL-101/20%FLG composite is 5.79-6.54 times that of MIL-101. Adding FLG is conducive to the formation of heat transfer channels in MIL-101/FLG adsorber and the rapid removal of adsorption heat. The heating and cooling rate of MIL-101/FLG adsorber is ~2.2 times that of MIL-101 adsorber. Under typical adsorption water chiller conditions, the specific cooling power (SCP) and coefficient of performance (COP) of the MIL-101/FLG-water working pair is 72.2–81.0 W kg−1 and 0.187–0.202, respectively, at desorption temperatures of 70 °C and 90 °C, which is 1.43–1.56 times higher than the MIL-101-water working pair. The excellent structural and adsorption/desorption cyclic stability of MIL-101/FLG composite is verified after 50 consecutive cycles. It can provide a promising adsorbent candidate (MIL-101/FLG composite) in adsorption water chiller process.

scholarly journals Effects of Evaporator and Condenser in the Analysis of Adsorption Chillers

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1901
Author(s):  
Woo Su Lee ◽  
Moon Yong Park ◽  
Xuan Quang Duong ◽  
Ngoc Vi Cao ◽  
Jae Dong Chung
Keyword(s):  
Numerical Models ◽  
Numerical Approach ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Parameter Method ◽  
Adsorption Chiller ◽  
Numerical Studies ◽  
Lumped Parameter ◽  
Condenser Temperature ◽  
Lumped Parameter Method

In a survey of the literature from the last 20 years, 20% of the numerical models used to analyze the performance of adsorption chillers assumed the evaporator and condenser were ideal, with a fixed evaporation temperature and condenser temperature, and ignored interactions between the adsorption bed and evaporator/condenser. Even when the interaction with the evaporator and condenser was included, the other 80% of studies modeled the adsorption bed based on the LPM (lumped parameter method), which ignores the geometry effect and contact resistance of the bed, and thus reduces the accuracy of the analysis. As a consequence, these earlier numerical studies overestimated the system performance of the adsorption chiller. In this study, we conducted a refined numerical approach which avoids these limitations, producing estimates in close agreement with experimental results. Compared with our approach, the models with ideal treatment of evaporator and condenser overestimated COP (coefficient of performance) and SCP (specific cooling power) by as much as 16.12% and 24.64%, respectively. The models based on LPM overestimated COP and SCP by 22.82% and 11.28%, compared to our approach.

scholarly journals Performance Results of a Solar Adsorption Cooling and Heating Unit

2020 ◽  
Author(s):  
Tryfonas Roumpedakis ◽  
Salvatore Vasta ◽  
Alessio Sapienza ◽  
George Kallis ◽  
Sotirios Karellas ◽  
...  
Keyword(s):  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Solar Thermal Energy ◽  
Cooling Mode ◽  
Heating Unit ◽  
Adsorption Chiller ◽  
Maximum Coefficient ◽  
Solar Powered ◽  
Evacuated Tube Collectors ◽  
Performance Results

The high environmental impact of conventional methods of cooling and heating has increased the need for renewable energy deployment for covering thermal loads. Towards that direction, the proposed system aims at offering an efficient solar powered alternative, coupling a zeolite-water adsorption chiller with a conventional vapor compression cycle. The system is designed to operate under intermittent heat supply of low-temperature solar thermal energy (&lt;90 &deg;C) provided by evacuated tube collectors. A prototype was developed and tested in cooling mode operation. The results of separate components testing showed that the adsorption chiller was operating efficiently, achieving a maximum coefficient of performance (COP) of 0.65. With respect to the combined performance of the system, evaluated on a typical week of summer in Athens, the maximum reported COP was approximately 0.575, mainly due to the lower driving temperatures at a range of 75 &deg;C. The corresponding mean energy efficiency ratio (EER) obtained was 5.8.

scholarly journals Using adsorption chillers for utilising waste heat from power plants

2019 ◽  
Vol 23 (Suppl. 4) ◽  
pp. 1143-1151 ◽  
Author(s):  
Karol Sztekler ◽  
Wojciech Kalawa ◽  
Sebastian Stefanski ◽  
Jaroslaw Krzywanski ◽  
Karolina Grabowska ◽  
...  
Keyword(s):  
Power Generation ◽  
Energy Efficiency ◽  
Power Plant ◽  
Power Plants ◽  
Waste Heat ◽  
Primary Energy ◽  
Simulation Software ◽  
Coefficient Of Performance ◽  
Low Grade ◽  
Adsorption Chiller

At present, energy efficiency is a very important issue and it is power generation facilities, among others, that have to confront this challenge. The simultaneous production of electricity, heat and cooling, the so-called trigeneration, allows for substantial savings in the chemical energy of fuels. More efficient use of the primary energy contained in fuels translates into tangible earnings for power plants while reductions in the amounts of fuel burned, and of non-renewable resources in particular, certainly have a favorable impact on the natural environment. The main aim of the paper was to investigate the contribution of the use of adsorption chillers to improve the energy efficiency of a conventional power plant through the utilization of combined heat and power waste heat, involving the use of adsorption chillers. An adsorption chiller is an item of industrial equipment that is driven by low grade heat and intended to produce chilled water and desalinated water. Nowadays, adsorption chillers exhibit a low coefficient of performance. This type of plant is designed to increase the efficiency of the primary energy use. This objective as well as the conservation of non-renewable energy resources is becoming an increasingly important aspect of the operation of power generation facilities. As part of their project, the authors have modelled the cycle of a conventional heat power plant integrated with an adsorption chiller-based plant. Multi-variant simulation calculations were performed using IPSEpro simulation software.

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