This study investigated the optimal design of a capillary heat exchanger device for the heat pump system and its innovative engineering application in a building. The overall aim was to use a capillary heat exchanger to obtain energy in coastal areas for promoting renewable energy in low-carbon building design. Initially, the main factors affecting the efficiency of the capillary heat exchanger were identified, a mathematical model was then established to analyse the heat transfer process. The analysis showed the flow rate and the capillary length are the key factors affecting the efficiency of the capillary heat exchanger. Secondly, to optimize the structural design of the capillary heat exchanger, the heat energy transfer is calculated with different lengths of the capillary under various flow rates in summer and winter conditions, respectively. Thirdly, a typical building is selected to analyse the application of the capillary heat exchanger for extracting energy in the coastal area. The results show the performance of the selected capillary heat exchanger heat pump system, in winter, the heat energy transfer rate is 60 W/m² when the seawater temperature is 3.7 °C; in summer, the heat energy transfer rate is 150 W/m² when the seawater temperature is 24.6 °C. Finally, the above field test results were examined using a numerical simulation model, the test and simulation results agree with each other quite well. This paper is conducive in promoting the development of the capillary heat exchanger heat pump as an innovative sustainable technology for net-zero energy and low carbon buildings using renewable energy in coastal areas.

Practical application: A recently proposed capillary heat exchanger is used as an energy extraction and utilisation device to obtain energy in coastal areas for promoting renewable energy in low-carbon building design. This paper explores the application of a capillary heat exchanger as both cold and heat sources for application in typical low-rise buildings. The analysis of the heat energy transfer rate of a typical low-rise building located in a coastal area in summer and winter provides guidance for the application of capillary heat exchangers.

本研究研究了用于热泵系统的毛细管换热器的最佳设计及其在建筑中的创新工程应用。总体目标是使用毛细管热交换器在沿海地区获取能源，以促进低碳建筑设计中的可再生能源。最初，确定影响毛细管热交换器效率的主要因素，然后建立一个数学模型来分析传热过程。分析表明，流速和毛细管长度是影响毛细管热交换器效率的关键因素。其次，为了优化毛细管热交换器的结构设计，分别在夏季和冬季条件下，在不同流量下，使用不同长度的毛细管来计算热能传递。第三，选择一栋典型的建筑物来分析毛细管热交换器在沿海地区提取能量的应用。结果表明，所选的毛细管换热器热泵系统的性能，在冬季，热能传递速率为60 W / m²当海水温度为3.7°C时; 在夏季，海水温度为24.6°C时，热能传递速率为150 W / m ²。最后，使用数值模拟模型对上述现场测试结果进行了检验，测试结果与仿真结果非常吻合。本文有助于促进毛细管热交换器热泵的发展，将其作为沿海地区使用可再生能源的零能耗和低碳建筑的可持续创新技术。

实际应用：最近提出的毛细管热交换器被用作能量提取和利用装置，以在沿海地区获取能量，以促进低碳建筑设计中的可再生能源。本文探讨了毛细管热交换器作为典型低层建筑中的冷热源的应用。对夏季和冬季位于沿海地区的典型低层建筑的热能传递速率的分析为毛细管热交换器的应用提供了指导。