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A configuration of the prototype of the cascade heat pump system
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Transient performance of a cascade heat pump system is experimentally investigated. The cascade heat pump consists of 4 systems: the chilled water system, the low-temperature refrigeration cycle using R22, the high-temperature heat pump cycle using R134a and the hot water system. The cascade heat pump produces both chilled water for cooling applica...
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... effect of the low and high hot water flow rate is investigated. Fig.1 shows the experimental setup of a cascade heat pump system. ...
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Citations
... The instantaneous heat transfer coefficient of the cold water phase-change heat exchanger [24] is calculated using Formulas (11)- (14), and the results are shown in Figure 10. From the above analysis, it can be seen that, as the intermediate side inlet water temperature decreased, the average heat transfer coefficients of the CPHE were 0.60, 0.66, 0.71, and 0.75 kW/m 2 ·K for each operating condition. ...
Under active icing conditions, the heat transfer performance of the CPHE has a significant impact on the system’s efficiency and energy consumption. Using the enthalpy-porosity method for describing the solidification process of liquids, the simulation and analysis of the effects of different parameter changes on the CPHE heat transfer performance were conducted to clarify the effects of the changes in the intermediary side inlet water temperature, intermediate water flow rate, and cold water flow rate on the heat transfer process in the CPHE. According to our results, changing the intermediary inlet water temperature has a greater impact on the heat transfer process in the cold-water phase-change heat exchangers. For every decrease of 0.5 °C in the intermediary side inlet water temperature, the average heat transfer coefficient increases by approximately 50 W/m2-K. Changes in the intermediary water flow rate affect the cold water phase-change heat exchanger’s heat transfer process. By increasing the intermediary water flow rate, the average heat transfer coefficient of a cold water phase-change heat exchanger can be improved, but the growth decreases, and the maximum flow rate of the intermediary water should not exceed 0.5 m per second. A change in the cold water flow rate in the cold water phase-change heat exchanger’s heat transfer process has a small impact on the cold water flow rate, increasing by 0.02 m/s each, with the average heat transfer coefficient increasing by 20 W/m2-K.
... With the operation of the system, the COP gradually decreases to a certain range and fluctuates steadily until the unit is shut down [23], and the COP is reduced to 0. Considering that the heat pump system operates at a constant flow rate, the unit COP changes as the operation time. ...
In order to study the influence on the effective energy efficiency ratio, the energy consumption characteristics of a cold-water phase change heat pump system are discussed in this article. An experimental system of the cold-water phase-change energy heat pump system is designed and constructed, and then the deicing energy consumption and unit energy consumption of the heat pump system are analyzed by computational intelligence-powered methods. At last, the primary energy utilization ratio of the heat pump system is calculated. The results show that under the setting conditions, the deicing capacity of the heat pump system is about 0.135, the primary energy utilization ratio is about 1.145, and the COP (coefficient of performance) of the heat pump unit is between 2.8 and 3.2. Considering the system’s deicing energy consumption, the effective COP of the unit is between 2.42 and 2.76, so from this point, this kind of heat pump system can be widely used in the future. In order to improve the effective COP of the unit, the processes of ice making and melting should be further optimized to reduce heat loss and power loss.
... Kim et al. [13] investigated the optimal intermediate temperature of a cascade heat pump used for hot water generation. Nenkaew and Tangthien [14] conducted an experimental study on the transient performance of cascade heat pump used for cooling, refrigeration, heating and hot water generation. Soltani et al. [15] compared the performance of single stage and hydronic cascade heat pumps for generating hot water. ...
The use of cascade heat pumps for hot water generation has gained much attention in recent times. The big question that has attracted much research interest is how to enhance the performance and energy saving potential of these cascade heat pumps. This study therefore proposed a new cycle to enhance performance of the cascade heat pump by adopting an auxiliary heat exchanger (AHX) in desuperheater, heater and parallel positions at the low stage (LS) side. The new cascade cycle with AHX in desuperheater position was found to have better performance than that with AHX at heater and parallel positions. Compared to the conventional cycle, heating capacity and coefficient of performance (COP) of the new cascade cycle with AHX in desuperheater position increased up to 7.4% and 14.9% respectively.
