ABSTRACT

Among non-toxic and inflammable working fluids, carbon dioxide (CO₂) proving a possible choice of refrigerant is gaining full status because of its reducing capacity of global warming and ozone depletion. Heat pump (HP) equipment uses energy more rationally to heat water by reducing emissions and global warming caused by conventional refrigerants. HP capability demands an environmentally friendly refrigerant for their full utilization and high energy saving as well to attaining higher coefficient of performance (COP) without much design corrections. CO₂ is checked for sustainability to eliminate the standardized refrigerants such as chlorofluorocarbons (CFC) and hydro-CFC. In this work, the performance of CO₂ as an alternate refrigerant in HP for heating water at different pressure, flow rates, evaporator fan speed and preheating have been investigated. HP is accommodated with two condensers. The results showed that the increased mass flow rate had increased COP, overall heat transfer (HT) coefficient (U) and HT. However, logarithmic mean temperature difference was decreased for increasing evaporator’s fan speed and pressure. The outlet water temperature (T_WO) of second condenser increased with decreasing water flow rate. Improved COP, HT and T_WO of HP are observed from the experimental evaluation in case of preheating of water.

中文翻译：

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使用可再生跨临界 CO2 制冷剂加热水的热泵性能特征

摘要

在无毒和易燃的工作流体中，二氧化碳 (CO ₂ ) 证明是一种可能的制冷剂选择，由于其减少全球变暖和臭氧消耗的能力而获得了充分的地位。热泵 (HP) 设备通过减少传统制冷剂造成的排放和全球变暖，更合理地使用能源来加热水。HP 能力需要一种环保制冷剂，以充分利用它们并实现高节能，并在不进行大量设计修正的情况下获得更高的性能系数 (COP)。检查CO ₂的可持续性，以消除标准制冷剂，如氯氟烃 (CFC) 和氢氟氯化碳。在这项工作中，CO ₂的性能已经研究了作为 HP 中不同压力、流速、蒸发器风扇速度和预热水加热的替代制冷剂。HP 装有两个冷凝器。结果表明，增加的质量流量增加了 COP、总传热 (HT) 系数 ( U ) 和 HT。然而，对数平均温差随着蒸发器风扇速度和压力的增加而减小。出口水温（Ť _WO第二冷凝器的）随水的流速增加。改进的COP，HT和Ť _WO HP都是从实验评价在水预热的情况下观察到的。