Performance analysis of building-integrated earth-air heat exchanger retrofitted with a supplementary water system for cooling-dominated climate in Taiwan

Abstract The thermal performance of a building-integrated earth-air heat exchanger (EAHE) retrofitted with a supplementary water piping system has been analyzed. The EAHE system has no excavation cost by integrating with the building foundation and gets better cooling performance by flowing supplementary water from residential water well to the foundation-integrated water-based EAHE (FIWEAHE) system. The experimental and numerical investigation was conducted to analyze the air conditioning performance of the FIWEAHE system. The simulated bulk temperature and humidity ratio of outlet air were validated with the year-round experimental data. After mixing with the circulating water from the residential water well, the cooling capacity of the FIWEAHE system enhanced from 3.21 kW to 4.84 kW, and its moisture removal rate soared from 1.97 kg/h to 4.24 kg/h during summer operation. The outlet air temperature varying from 24-26°C in summer and 20-21°C in winter can meet the standard of indoor thermal comfort. The mean COP of the FIWEAHE system during summer and winter operation is calculated as 10.5 and 1.74, respectively. Relation curves among air velocity and energy-efficient design of pipe geometry were developed to be the future design guideline of the FIWEAHE system.