Numerical analysis of the efficiency of earth to air heat exchange systems in cold and hot-arid climates

Abstract

In order to examine and compare the efficiency of earth to air heat exchanger (EAHE) systems in hot-arid (Yazd) and cold (Hamadan) climates in Iran a steady state model was developed to evaluate the impact of various parameters including inlet air temperatures, pipe lengths and ground temperatures on the cooling and heating potential of EAHEs in both climates. The results demonstrated the ability of the system to not only improve the average temperature and decrease the temperature fluctuation of the outlet air temperature of EAHE, but also to trigger considerable energy saving. It was found that in both climates, the system is highly utilized for pre-heating, and its usage is unfeasible in certain periods throughout the year. In winter, EAHEs have the potential of increasing the air temperature in the range of 0.2-11.2°C and 0.1-17.2°C for Yazd and Hamadan, respectively. However, in summer, the system decreases the air temperature for the aforementioned cities in the range of 1.3-11.4°C and 5.7-11.1°C, respectively. The system ascertains to be more efficient in the hot-arid climate of Yazd, where it can be used on 294 days of the year, leading to 50.1-63.6% energy saving, when compared to the cold climate of Hamadan, where it can be used on 225 days of the year resulting in a reduction of energy consumption by 24.5-47.9%.

Earth-Cooling Air Tunnels for Thermal Power Plants: Initial Design by CFD Modelling

“…The three-dimensional and steady-state fluid dynamic fundamental equations are applied for solving the air flow dynamic and the heat transfer process between the air, the pipe and the soil. Heat transfer occurs by convection between the air and the pipe, and by conduction between the air and the soil through the pipe wall and the soil surrounding the pipe [51]. The air is assumed incompressible [52,53].…”

Utilization of Earth-to-Air Heat Exchanger to Pre-Cool/Heat Ventilation Air and Its Annual Energy Performance Evaluation: A Case Study

“…The evaporative cooling [18] and photovoltaic thermal (PVT) system [19] can be used to precool and preheat ventilation air in the cooling and heating seasons, respectively. Moreover, the earth-to-air heat exchanger (EAHE) can be treated as a low-grade heat source in winter and cold source in summer for preheating and precooling ventilation air, respectively [20].…”

A literature review of night ventilation strategies in buildings

“…Given that HVAC constitutes a significant proportion of building energy end use [4], energy efficient heating and cooling are critical to sustainable development. To reduce the energy demand of buildings whilst maintaining comfort levels, the adoption of various passive energy saving techniques such as night ventilation, exclusively or coupled with novel thermal energy storage like phase change materials (PCMs) [5][6][7] or other energy-efficient systems such as wind-catchers [8], earth to air heat exchange systems [9,10], atriums [11], and so forth is required.…”