Modeling Earth-to-Air Heat Exchangers In Severe Climate

Abstract

Harsh weather conditions often require heating during winters and cooling in summers. In many developing countries, power outages caused by energy shortages cause discomfort for the residents. Thus, more sustainable systems for air conditioning are desirable in these countries. The present study proposes an examination of the viability of Earth-to-Air Heat Ex-changers (EAHE) in severe environments (extreme summer and winter seasons) and comprises numerical modeling using COMSOL Multiphysics. In most existing studies, EAHE systems are examined and validated for particular field conditions. Despite the valuable information from these studies, it is vital to perform investigations within a regional context, considering specific environmental conditions at the regional scale. The current research addresses the performance of Earth-to-Air Heat Exchangers in a severe climate typical of the region of Islamabad. To this end, thermal properties are selected according to soil profiles specific of this region. The annual mean earth temperature is carefully chosen from RETScreen daily records in the same region. Models are tested against analytic solutions in a 2-D context and validated using large-scale field tests. The complete numerical model integrates heat transfer in the ground where em-bedded piping is subject to air circulation. Heat transfer occurs between the piping system and the surrounding soil, which results in heating or cooling of the circulating air mass, depending on the seasonal conditions. The results obtained in field conditions validated by actual experiments show interesting predictions of air temperatures at the outlet even in a severe climate. This depicts that ground temperatures preserved from climatic conditions can benefit EAHE systems even in severe climate conditions.

Keywords

• renewable energy
• eahe systems
• severe climate
• ground temperature
• comsol multiphysics
• airflow and heat transfer in pipes