The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
R Z Wang - One of the best experts on this subject based on the ideXlab platform.
-
an air source hybrid absorption compression heat pump with large Temperature Lift
Applied Energy, 2021Co-Authors: J Gao, R Z WangAbstract:Abstract High-Temperature heat pump is gaining more and more research attention due to the efficient heat supply for industrial uses, which includes waste heat-source, water-source, and air-source types. Although air heat source has lower energy grade, its superior availability is attractive. However, large Temperature Lift is necessary to fill in the gap between the low Temperature ambient air and high Temperature supply, which cannot be fulfilled by current heat pumps. In this study, a novel air-source hybrid absorption-compression heat pump is proposed to address this issue, in which the compression sub-cycle and absorption sub-cycle are thermally coupled for stepped Temperature Lift. Compared with the conventional air-source heat pump, a large Temperature Lift (over 90 °C) and relatively good thermodynamic perfectibility (0.34) are obtained. As the Temperature Lift increases from 70 °C to 110 °C, the coefficient of performance changes from 1.7 to 1.2. Moreover, heat recovery between the two sub-cycles is achieved to reduce the heat exchange capacity with air, thus saving air–liquid heat exchanger area and cost. Via the integration of relatively mature technologies, the proposed system provides a feasible and efficient way to upgrade ambient heat for industrial uses, and it is technologically available in different capacities.
-
Enlarged Temperature Lift of hybrid compression-absorption heat transformer via deep thermal coupling
Energy Conversion and Management, 2021Co-Authors: J Gao, R Z WangAbstract:Abstract The energy level mismatch between heat sources and industry users has posed a huge barrier for the wide application of local waste heat recovery, which cannot be efficiently addressed by traditional options due to the limited Temperature Lift. To fill this gap, a hybrid heat transformer is proposed to achieve large Temperature Lift via deep thermal coupling between compression and absorption sub-cycles. Firstly, simulation shows that 42.1 kW heat output (at 100 °C) is provided with the costs of 20.0 kW electricity and 67.4 kW waste heat (at 45 °C), resulting in a COP of 2.15 and a large Temperature Lift of 55 °C. Secondly, an experimental prototype was established for performance validation, which stably upgraded the waste heat from 47–51 °C to 99–102 °C with an overall COP of 1.81. Further investigation shows that the proposed system is quite flexible with waste heat source Temperatures of 30–60 °C and output Temperatures of 90–115 °C. Such an effective heat transformer with large Temperature Lift could be promoted for the efficient utilization of low-grade waste heat, and contribute to the industrial decarbonization.
-
experimental investigation on a dual mode thermochemical sorption energy storage system
Energy, 2017Co-Authors: T. Yan, R Z Wang, Jie ZhuAbstract:A dual-mode thermochemical sorption energy storage system using working pair of expanded graphite/SrCl2-NH3 was proposed for seasonal solar thermal energy storage. The proposed system has two working modes to produce useful heat with an expected Temperature during the discharging phase according to the different ambient Temperatures, including the direct heating supply and Temperature-Lift heating supply. Solar thermal energy is transformed into chemical bonds and stored in summer, and the stored energy is released in the form of chemical reaction heat in winter. The direct heating supply mode is adopted at a relatively high ambient Temperature in winter. The effective energy storage density is higher than 700 kJ/kg and the corresponding system COP is 0.41 when the heat output Temperature and ambient Temperature are 35 °C and 15 °C, respectively. The specific heating power increases with the decrease of heat output Temperature for a given ambient Temperature. The Temperature-Lift heating supply mode is adopted to upgrade the heat output Temperature at a low ambient Temperature below 0 °C in winter. It can produce heat with a Temperature above 70 °C although the ambient Temperature is as low as −15 °C. It is desirable to further improve the system performance using low mass ratio and high global conversion. Experimental results showed the advanced dual-mode thermochemical sorption energy storage technology is feasible and effective for seasonal solar thermal energy storage.
-
Multi-functional three-phase sorption solar thermal energy storage cycles for cooling, heating, and heat transformer
Applied Thermal Engineering, 1Co-Authors: Abel Mehari, R Z WangAbstract:Abstract Thermal energy storage based on sorption method is attractive in view of energy storage density, storage period, and flexibility. Three-phase sorption thermal energy storage is advantageous from high energy storage density, but its Temperature Lift is low. Besides, further energy storage density enhancement is needed to make the storage system more compact. In this paper, multi-functional three-phase sorption thermal energy storage cycles are proposed to achieve a higher Temperature Lift and energy storage density simultaneously, in which different applications can be evident including interseasonal heating, combined cooling and heating in summer, and heat transformer in summer and winter. The performance of the proposed cycles for three operating modes is evaluated analytically with a working pair of LiCl/H2O, due to its high absorption and crystallization enthalpy. Results showed that the multi-functional three-phase sorption thermal energy storage cycles obtained a Temperature Lift of 65°C and an energy storage density up to 1307 Wh/kg, which cannot be realized with a conventional three-phase cycle. Moreover, a combined cold and heat storages at 15°C and 60°C, respectively, and discharging Temperature more than 100°C are achieved. With these proposed cycles, a wider range of applications could be expected for three-phase sorption thermal energy storage.
Roberto Best - One of the best experts on this subject based on the ideXlab platform.
-
Theoretical and experimental comparison of the performance of a single-stage heat transformer operating with water/lithium bromide and water/Carrol™
International Journal of Energy Research, 2002Co-Authors: Wilfrido Rivera, Rosenberg J. Romero, M.j. Cardoso, J. Aguillón, Roberto BestAbstract:This paper compares under the same operating conditions, the theoretical and experimental performance of a single-stage heat transformer operating with the water/lithium bromide and the water/Carrol™ mixtures, where Carrol™ is a mixture of lithium bromide and ethylene glycol [(CH2OH)2] in the ratio 1:4.5 by weight patented by Carrier Corp. Flow ratios, gross Temperature Lifts, useful heat, and coefficients of performance are plotted for the heat transformer against Temperatures and solution concentrations. Because the water/Carrol™ mixture has higher solubility than water/lithium bromide and high experimental values were obtained for the gross Temperature Lift, it seems to be a better alternative mixture to be used in absorption heat transformers. Copyright © 2002 John Wiley & Sons, Ltd.
-
Experimental evaluation of a single-stage heat transformer operating with the water/Carrol™ mixture
Energy, 1999Co-Authors: Wilfrido Rivera, Roberto Best, Rosenberg J. Romero, C.l. HeardAbstract:Abstract This paper describes experimental results obtained with a single-stage heat transformer (SSHT). Many combinations of fluid pairs have been proposed although only the water/lithium bromide mixture has been widely used. The experimental work was done using the water/Carrol™ mixture, where Carrol™ is a mixture of LiBr and ethylene glycol [(CH2OH)2] in the ratio 1:4.5 by weight. Flow ratios, gross Temperature Lifts, useful heat, and coefficients of performance are plotted for the heat transformer vs Temperatures and solution concentrations. Because the water/Carrol™ mixture has higher solubility than water/lithium bromide and high experimental values are obtained for the gross Temperature Lift, it is a preferred mixture.
-
Experimental performance of ternary solutions in an absorption heat transformer
International Journal of Energy Research, 1998Co-Authors: R. M. Barragán, C.l. Heard, V. M. Arellano, Roberto BestAbstract:In this work, results from experiments with ternary solutions in an absorption heat transformer are presented. The experiments were performed under controlled conditions using water/lithium chloride/zinc chloride and water/calcium chloride/zinc chloride solutions as working pairs. The results showed that the gross Temperature Lift is increased with regard to the results obtained using binary solutions because the concentration of the solutions was enhanced. The water/lithium chloride/zinc chloride solution showed a generally better performance than the water/calcium chloride/zinc chloride mixture. The highest gross Temperature Lift for the former solution was 37.5°C for an absorber Temperature of 96°C. This result compared favourably to that previously obtained for water/lithium bromide in the University of Salford.
-
EXPERIMENTAL PERFORMANCE OF THE SYSTEM WATER/MAGNESIUM CHLORIDE IN A HEAT TRANSFORMER
International Journal of Energy Research, 1997Co-Authors: R. M. Barragán, C.l. Heard, Roberto Best, V. M. Arellano, F.a. HollandAbstract:Absorption heat transformers are devices with the unique capability of raising the Temperature of part of a low grade heat source whilst simultaneously rejecting the rest of the heat at a lower Temperature. The gross Temperature Lift that could be attained in the process depends on the characteristics of the working pair. Many combinations of working fluid/absorbent have been proposed although until now the water/lithium bromide system is the most widely used. Experimental results for the water/magnesium chloride working pair in an absorption heat transformer are presented. Two different ranges for the absorber Temperature were investigated. The absorber Temperature varied from 81 to 89°C and from 91 to 101°C. For the first case, the gross Temperature Lift was calculated between 7⋅8 and 10⋅2°C whilst for the second case the gross Temperature Lift was found to be between 15 and 18⋅4°C. For both sets of experiments, the heat input was maintained constant and the calculated coefficient of performance was related to the absorber Temperature, the flow ratio and the effectiveness of the economizer. © 1997 by John Wiley & Sons, Ltd.
Reinhard Radermacher - One of the best experts on this subject based on the ideXlab platform.
-
Performance enhancement of a compressive thermoelastic cooling system using multi-objective optimization and novel designs
International Journal of Refrigeration, 2015Co-Authors: Suxin Qian, Reinhard Radermacher, Yunho Hwang, Abdullah Alabdulkarem, Jiazhen Ling, Jan Muehlbauer, Ichiro TakeuchiAbstract:Abstract Thermoelastic cooling is a recently proposed, novel solid-state cooling technology. It has the benefit of not using high global warming potential (GWP) refrigerants which are used in vapor compression cycles (VCCs). Performance enhancements on a thermoelastic cooling prototype were investigated. A few novel design options aiming to reduce the cyclic loss were proposed. It was found that the maximum Temperature Lift increased from 6.6 K to 27.8 K when applying the proposed novel designs, corresponding to 0–152 W cooling capacity enhancement evaluated under 10 K water–water system Temperature Lift. In addition, a multi-objective optimization problem was formulated and solved using the genetic algorithm to maximize the system capacity and coefficient of performance (COP). With all the novel designs, the optimization could further enhance 31% COP, or 21% cooling capacity, corresponding to COP of 4.1 or 184 W maximum cooling capacity.
-
Analytical investigation of low Temperature Lift energy conversion systems with renewable energy source
Applied Thermal Engineering, 2014Co-Authors: Hoseong Lee, Yunho Hwang, Reinhard RadermacherAbstract:Abstract The efficiency of the renewable energy powered energy conversion system is typically low due to its moderate heat source Temperature. Therefore, improving its energy efficiency is essential. In this study, the performance of the energy conversion system with renewable energy source was theoretically investigated in order to explore its design aspect. For this purpose, a computer model of n -stage low Temperature Lift energy conversion (LTLEC) system was developed. The results showed that under given operating conditions such as Temperatures and mass flow rates of heat source and heat sink fluids the unit power generation of the system increased with the number of stage, and it became saturated when the number of staging reached four. Investigation of several possible working fluids for the optimum stage LTLEC system revealed that ethanol could be an alternative to ammonia. The heat exchanger effectiveness is a critical factor on the system performance. The power generation was increased by 7.83% for the evaporator and 9.94% for the condenser with 10% increase of heat exchanger effectiveness. When these low Temperature source fluids are applied to the LTLEC system, the heat exchanger performance would be very critical and it has to be designed accordingly.
-
Experimental investigation of novel heat exchanger for low Temperature Lift heat pump
Energy, 2013Co-Authors: Hoseong Lee, Reinhard Radermacher, Yunho Hwang, Ho-hwan ChunAbstract:Abstract In this paper, the thermal and hydraulic performance of a novel low Temperature Lift heat exchanger (LTLHX) was experimentally investigated. The novel LTLHX was developed to improve the performance of the conventional plate type heat exchanger (PHX) under low Temperature Lift operating conditions. The optimized novel LTLHX was fabricated and investigated experimentally with various operating conditions. The heat transfer coefficient correlation and friction factor correlation of the water-side in the novel LTLHX were formulated from the experimental data. The overall heat transfer coefficient of the novel LTLHX with ammonia ranged from 1300 to 2000 W K −1 m −2 , and the pressure drop per length of the water-side ranged from 4 to 10 kPa m −1 . The refrigerant-side heat transfer coefficient ranged from 2900 to 5000 W K −1 m −2 , and water-side heat transfer coefficient ranged from 3900 to 5100 W K −1 m −2 . The overall heat transfer performance of the novel LTLHX was more than double that of the PHX at the same operating conditions. Moreover, the water-side pressure drop of the novel heat exchanger was drastically lower than that of the PHX. It was due to the balanced thermal and hydraulic performance of the novel heat exchanger.
-
Thermal and hydraulic performance of sinusoidal corrugated plate heat exchanger for low Temperature Lift heat pump
International Journal of Refrigeration, 2013Co-Authors: Hoseong Lee, Reinhard Radermacher, Yunho Hwang, Ho-hwan ChunAbstract:Abstract Thermal and hydraulic performance of a sinusoidal corrugated plate heat exchanger (PHX) was investigated for the application of a low Temperature Lift heat pump (LTLHP), which requires unique operating conditions. The water-side heat transfer coefficient and pressure drop of the PHX were obtained through the experimental test. The refrigerant-side heat transfer performance was investigated by varying several parameters. The PHX performance was poor due to low refrigerant mass flux. The PHX needs better balance in two fluids for the LTLHP application. From the current study, it is concluded that the conventional PHX applied for the LTLHP application is limited by two main factors: a large pressure drop on the water-side due to corrugated shape, and a low heat transfer performance due to the low refrigerant-side heat transfer performance. In order to address these drawbacks, heat exchanger designs must be improved by optimizing its geometry and flow area asymmetrically for each fluid.
-
Development of a vapor compression cycle with a solution circuit and desorber/absorber heat exchange
International Journal of Refrigeration, 1997Co-Authors: Qin Zhou, Reinhard RadermacherAbstract:Abstract A vapor compression cycle with a solution circuit and desorber/absorber heat exchange (DAHX) has been investigated experimentally using the ammonia/water mixture. A breadboard heat pump was designed and built to measure the cycle performance. COPs in the range of 1.2–1.8 were obtained experimentally for a Temperature Lift between 60 and 80°C. The cooling capacities were between 7 and 12 kW, which increased with an increase of the ammonia concentration. The pressure ratios encountered were in the range of 2–6. A COP of 1.44 at the Temperature Lift of 79°C was recorded with a cooling capacity at 10.25 kW. The experimental results are compared to that of the single-stage and two-stage cycle. The two-stage system had the highest Temperature Lift (110–120°C) and the lowest COP (0.69–1.04). The single-stage system has the highest COP (2.2–3.5) but the lowest Temperature Lift (40°C). Also, a solution bypass between the Absorber I outlet and Desorber II inlet was proposed to improve the cycle performance. The experimental results showed that the COP varied in the range of 1–2%, while the Temperature Lift increased by the range between 0 and 6°C. In addition, the analysis of the test result uncertainties was made.
C.l. Heard - One of the best experts on this subject based on the ideXlab platform.
-
Experimental evaluation of a single-stage heat transformer operating with the water/Carrol™ mixture
Energy, 1999Co-Authors: Wilfrido Rivera, Roberto Best, Rosenberg J. Romero, C.l. HeardAbstract:Abstract This paper describes experimental results obtained with a single-stage heat transformer (SSHT). Many combinations of fluid pairs have been proposed although only the water/lithium bromide mixture has been widely used. The experimental work was done using the water/Carrol™ mixture, where Carrol™ is a mixture of LiBr and ethylene glycol [(CH2OH)2] in the ratio 1:4.5 by weight. Flow ratios, gross Temperature Lifts, useful heat, and coefficients of performance are plotted for the heat transformer vs Temperatures and solution concentrations. Because the water/Carrol™ mixture has higher solubility than water/lithium bromide and high experimental values are obtained for the gross Temperature Lift, it is a preferred mixture.
-
Performance study of a double‐absorption water/calcium chloride heat transformer
International Journal of Energy Research, 1998Co-Authors: C.l. HeardAbstract:In order to increase the Temperature Lift and efficiency of single-absorption heat transformers there are other possible arrangements. Double-absorption heat transformers have a relatively simple design and smaller size compared to two-stage heat transformers. In this work, the thermodynamic performance of the water/calcium chloride system was modelled for a double-absorption heat transformer. Results indicate that Temperature Lifts of up to 40°C are possible with coefficients of performance close to 0·3. © 1998 John Wiley & Sons, Ltd.
-
Experimental performance of ternary solutions in an absorption heat transformer
International Journal of Energy Research, 1998Co-Authors: R. M. Barragán, C.l. Heard, V. M. Arellano, Roberto BestAbstract:In this work, results from experiments with ternary solutions in an absorption heat transformer are presented. The experiments were performed under controlled conditions using water/lithium chloride/zinc chloride and water/calcium chloride/zinc chloride solutions as working pairs. The results showed that the gross Temperature Lift is increased with regard to the results obtained using binary solutions because the concentration of the solutions was enhanced. The water/lithium chloride/zinc chloride solution showed a generally better performance than the water/calcium chloride/zinc chloride mixture. The highest gross Temperature Lift for the former solution was 37.5°C for an absorber Temperature of 96°C. This result compared favourably to that previously obtained for water/lithium bromide in the University of Salford.
-
EXPERIMENTAL PERFORMANCE OF THE SYSTEM WATER/MAGNESIUM CHLORIDE IN A HEAT TRANSFORMER
International Journal of Energy Research, 1997Co-Authors: R. M. Barragán, C.l. Heard, Roberto Best, V. M. Arellano, F.a. HollandAbstract:Absorption heat transformers are devices with the unique capability of raising the Temperature of part of a low grade heat source whilst simultaneously rejecting the rest of the heat at a lower Temperature. The gross Temperature Lift that could be attained in the process depends on the characteristics of the working pair. Many combinations of working fluid/absorbent have been proposed although until now the water/lithium bromide system is the most widely used. Experimental results for the water/magnesium chloride working pair in an absorption heat transformer are presented. Two different ranges for the absorber Temperature were investigated. The absorber Temperature varied from 81 to 89°C and from 91 to 101°C. For the first case, the gross Temperature Lift was calculated between 7⋅8 and 10⋅2°C whilst for the second case the gross Temperature Lift was found to be between 15 and 18⋅4°C. For both sets of experiments, the heat input was maintained constant and the calculated coefficient of performance was related to the absorber Temperature, the flow ratio and the effectiveness of the economizer. © 1997 by John Wiley & Sons, Ltd.
Wilfrido Rivera - One of the best experts on this subject based on the ideXlab platform.
-
Modeling of a Double Effect Heat Transformer Operating with Water/Lithium Bromide
Processes, 2019Co-Authors: Itzel N. Balderas-sánchez, J. Camilo Jiménez-garcía, Wilfrido RiveraAbstract:Absorption heat transformers are effective systems for a wide variety of applications; however, their main purpose is to upgrade thermal energy from several sources at low-Temperature up to a higher Temperature level. In the literature, several advanced configurations for absorption heat transformers have been reported which are mainly focused on the improvement of the gross Temperature Lift by the use of a double absorption process; however, these systems usually offer a reduced coefficient of performance. The present study proposes a new advanced configuration of an absorption heat transformer that improves the coefficient of performance utilizing a double generation process. The operation of the new configuration was numerically modeled, and the main findings were discussed and presented emphasizing the effect of several parameters on the system performance. The highest coefficient of performance and gross Temperature Lift were 0.63 and 48 °C, respectively. From its comparison with a single-stage heat transformer, it is concluded that the proposed system may achieve coefficient of performance values up to 25.8% higher than those obtained with the single-stage system, although achieving lower gross Temperature Lifts.
-
Thermodynamic analysis of a novel absorption heat transformer
Applied Thermal Engineering, 2019Co-Authors: Itzel N. Balderas-sánchez, Wilfrido Rivera, J. Camilo Jiménez-garcíaAbstract:Abstract Heat transformers are very useful for upgrading thermal energy to a higher Temperature level. Up until now, several heat transformer configurations have been proposed and studied. In general, these configurations have been designed to enhance the coefficient of performance or the gross Temperature Lift. However, the systems that enhance the gross Temperature Lift significantly reduce the coefficient of performance. In the present study, we propose a novel double-stage-double-effect heat transformer that makes it possible to achieve a high gross Temperature Lift without a significant reduction in the coefficient of performance. The proposed system was modeled. The main results are graphically represented and discussed in this paper. Moreover, a comparison of the performance of several heat transformer configurations is presented. The new configuration achieved a gross Temperature Lift as high as 82 °C and a maximum coefficient of performance of 0.46. Compared to a single-stage heat transformer, it is shown that for specific conditions, the proposed system achieves similar coefficients of performance but with considerably higher gross Temperature Lifts. Compared to a double-stage heat transformer, it is shown that with the proposed system, the coefficients of performance are always considerably higher and similar or even higher gross Temperature Lifts can be achieved.
-
Theoretical and experimental comparison of the performance of a single-stage heat transformer operating with water/lithium bromide and water/Carrol™
International Journal of Energy Research, 2002Co-Authors: Wilfrido Rivera, Rosenberg J. Romero, M.j. Cardoso, J. Aguillón, Roberto BestAbstract:This paper compares under the same operating conditions, the theoretical and experimental performance of a single-stage heat transformer operating with the water/lithium bromide and the water/Carrol™ mixtures, where Carrol™ is a mixture of lithium bromide and ethylene glycol [(CH2OH)2] in the ratio 1:4.5 by weight patented by Carrier Corp. Flow ratios, gross Temperature Lifts, useful heat, and coefficients of performance are plotted for the heat transformer against Temperatures and solution concentrations. Because the water/Carrol™ mixture has higher solubility than water/lithium bromide and high experimental values were obtained for the gross Temperature Lift, it seems to be a better alternative mixture to be used in absorption heat transformers. Copyright © 2002 John Wiley & Sons, Ltd.
-
Experimental evaluation of a single-stage heat transformer operating with the water/Carrol™ mixture
Energy, 1999Co-Authors: Wilfrido Rivera, Roberto Best, Rosenberg J. Romero, C.l. HeardAbstract:Abstract This paper describes experimental results obtained with a single-stage heat transformer (SSHT). Many combinations of fluid pairs have been proposed although only the water/lithium bromide mixture has been widely used. The experimental work was done using the water/Carrol™ mixture, where Carrol™ is a mixture of LiBr and ethylene glycol [(CH2OH)2] in the ratio 1:4.5 by weight. Flow ratios, gross Temperature Lifts, useful heat, and coefficients of performance are plotted for the heat transformer vs Temperatures and solution concentrations. Because the water/Carrol™ mixture has higher solubility than water/lithium bromide and high experimental values are obtained for the gross Temperature Lift, it is a preferred mixture.
