Thermal Characteristics of the Hybrid Ventilation Using Solar Chimney and Earth Tube Heat Exchanger

Abstract

This paper presents an experimental finding on the thermal characteristic of the hybrid ventilation by combining a Solar Chimney, SC, Earth Tube Heat Exchanger, ETHE, and small fan. A buoyancy driven natural ventilation causes an air flow inside the chimney. The latter is the pipe system buried underground, the ground operated as a heat sink. The combination of two effects would enhance the ventilation performance in which an indoor temperature could be reduced further than using just one. In this research, the square chimney made of steel plates with the outlet area of 0.09 m² and an underground pipe system made of PVC pipe diameter of 7.62 cm (3 inch) were assembled in the small demonstration house with the volume of 0.512 m³. The thermal characteristic of the chimney and earth tube heat exchanger was investigated by an outdoor test on the two identical houses, the reference and the hybrid ventilating houses. Air flow velocity, temperature and solar radiation were measured and be used in the analysis. It was found that the stack effect could provide natural ventilation according to the airflow velocity measurement; however, the better result can be achieved when the force flow due to the use of a small fan, 4.5 W, was adopted to increase the air velocity through the ETHE thus greater indoor temperature reduction can be achieved. The hybrid ventilation system proposes good thermal characteristic under the current study criteria evident by the indoor temperature reduction of 3.6^oC which is higher than other configuration by 33%. This technique is considered a prominent part of the building application