The effect of air humidity on the exergy efficiency of domestic heat pumps
The effect of air humidity on the exergy efficiency of domestic heat pumps
复制标题
DOI：
10.1016/j.enconman.2020.113054
复制
发表时间：
2020-10
影响因子：
10.4
通讯作者：
R. Zevenhoven;Özer Arnas
中科院分区：
文献类型：
--
作者：
R. Zevenhoven;Özer Arnas
热泵系统已经在制冷和将热量升级到消费者要求的温度水平中使用了几十年。北方和其他国家的私人住房正在放弃直接电加热、燃烧加热甚至区域加热，而转向使用廉价的可再生热源和电力的热泵。该系统的购买是由一个有吸引力的性能系数（COP），选择扭转热泵运行从冬季加热到夏季冷却，以及（廉价）零二氧化碳电力的可用性不断增加。使用火用分析评估热泵系统的能源效率是复杂的热源的功能，如建筑物围护结构中的空气湿度，变得重要，除了温度水平。在现代建筑物中，排气热回收（EAHR）系统每隔几个小时就更换一次建筑物内的空气，并伴随着湿度的净流入或流出。在本文中，火用分析，提出了量化的热泵系统的能量效率，部分取决于被加热使用地源热泵或空气源热泵的建筑围护结构的湿度。湿度控制引入了显著的能量损失。如图所示，EAHR单元可以导致显着增加的有效能效率，增加热泵提供的好处，这取决于室内与室外的温度和湿度，以及是否使用地源热泵或空气源热泵。使用2018年的天气数据，在最冷的月份，地源热泵显然比空气源热泵更有效，可以将芬兰的现代住宅空间全年保持在22 °C和50%的相对湿度。与地源热泵相比，空气源热泵的（火用）（实际上是电力）消耗高20%，最大（火用）效率分别为14%和11.5%。与EAHR系统的集成可以增加高达20%点的有效能效率，无论热泵的类型如何，这也是一项强大的投资。
Heat pump systems have been used for decades in refrigeration and the upgrading of heat to temperature levels demanded by consumers. Private housing in Northern Europe and other countries is moving away from direct electric heating, combustion-based heating and even district heating in favour of heat pumps that use a cheap renewable heat source and electricity. The system purchase is motivated by an attractive coefficient of performance (COP), the option to reverse the heat pump operation from heating during winter to cooling during summer, and the increasing availability of (cheap) zero-CO2electricity. Assessment of the energy efficiency of heat pump systems using exergy analysis is complicated by features of the heat reservoirs, such as humidity of air in a building envelope, becoming important besides temperature levels. In modern buildings, exhaust air heat recovery (EAHR) systems replace the air inside a building every few hours, with a net in- or outflux of humidity as side-effect. In this paper, an exergy analysis is presented that quantifies energy efficiency of a heat pump system as partly determined by the humidity of a building envelope being heated using a ground source or air source heat pump. Humidity control introduces a significant energy penalty. As shown, an EAHR unit can result in a significant increased exergy efficiency, adding to the benefits offered by the heat pump, depending on indoor versus outdoor temperature and humidity, and whether a ground source or air source heat pump is used. Using weather data for 2018, during the coldest months a ground heat source heat pump is clearly more efficient than an air source heat pump for maintaining a modern housing space in Finland at 22 °C and 50% relative humidity year-round. Exergy (in practice electricity) consumption is 20% higher for an air source heat pump compared to a ground source heat pump, with maximum exergy efficiencies of 14% and 11.5%, respectively. Integration with an EAHR system can add up to 20%-points to the exergetic efficiency, irrespective of the type of heat pump making also that a powerful investment.