基于实际运行数据的不同气候区冬季空气源热泵结霜特征分析

空气源热泵运行中存在的突出问题是室外机结霜而导致的机组性能下降。在实际应用中,当地气候条件下空气源热泵结霜的难易程度决定了大多数除霜技术的适用性。空气源热泵结霜的难易程度除了受气候影响外,还受系统运行性能甚至用户使用习惯的影响,难以做出定量的判断。因此本文提出结霜度时数的概念,以专门表征气候条件对结霜的影响。通过在国内多地采集空气源热泵实际运行数据,使得结霜度时数的计算更接近实际情况,再对运行数据进行拟合分析得到了不同功率类型的热泵系统的蒸发温度与室外干球温度之间的特征温差,此温差可以用来修正传统设计上所假设的某个定值。最后,根据不同特征温差下的结霜度时数分析,结合不同功率类型的热泵系统在国内275个城市的结霜特征,对这些城市进行了结霜气候分区,为空气源热泵系统进行气候适应性的设计以及控制策略开发提供参考。

Analysis of Frosting Characteristics of Air Source Heat Pumps in Winter Based on Actual Operation Data

A serious problem confronting theoperation of air source heat pumps is the degradation in performance caused by frosting ofoutdoor units. In practical applications, the probability of frosting in local climatic conditions determines the applicability of most defrosting technologies. The degree of frosting of air source heat pumps is not only affected by climate, but also affected by system performance and even the user''s usage habits. Consequently, it has been difficult to make a quantitative judgment of how to overcome these problems. Therefore, the concept of freezing degree hours is proposed to characterize the effects of climatic conditions on frost formation. In order to make the calculation of freezing degree hours closer to reality, this study collected operational data of air source heat pumps in many cities. The characteristic temperature difference between evaporation temperature and outdoor dry bulb temperature, with different power types, was obtained by fitting the operational data. The characteristic temperature difference can be used to correct the specific fixed value that is assumed in traditional designs. Finally, according to the analysis of freezing degree hours under different characteristic temperature differences, combined with the frost characteristics of different power types in 275 cities, the frost climate zones of these cities were classified, thereby providing a reference for the design of air source heat pump systems across different frost climate zones and the development of control strategies.