Experimental analysis and model verification of a new earth-to-air heat exchanger system

Abstract

Utilizing renewable energy and associated energy-efficient technology has developed a strategy for energy-saving in the most energy consumer sectors, especially for buildings. Geothermal energy as an energy-saving and environment-friendly renewable technology has been widely adopted in the building sector. In this study, a new earth-to-air heat exchanger (EAHE) system with vertically buried tubes utilizing geothermal energy was proposed. Compared to the conventional EAHE systems, its advantages mainly include high geothermal energy utilization efficiency and ease of condensate water discharge. To evaluate the thermal performance of the proposed new EAHE system, an experimental set-up was established and a series of tests were conducted. Meanwhile, a numerical model for this proposed system was developed and then validated by the monitored experimental data. The monitored result show that the outlet air temperature ranges from 22.4°C to 24.2°C as the air flow velocity set at 1 m/s, enabling it to be used as an efficient energy-saving technology for summer cooling of buildings. The validated result show that the developed numerical model has a highly consistent result with the monitored experimental data, and their maximum error for outlet air temperatures is less than 0.74°C with a relative deviation of 3.11%. Based on the developed numerical model, the inlet air velocity is certified with an important influence on the thermal performance of this proposed system.