Chotivisarut, N; Kiatsirirot, T & Lu Aye 2007 'Design of central solar heating with underground seasonal storage in Australia', the 6th Academic conference on Heat & Mass Transfer in Thermal Equipment (Eds: Kiatsiriroat, T; Vorayos, N; Wongsuwan, W & Sampattagul, S), Department of Mechanical Engineering, Chiang Mai University, 15-16 March 2007, Chiang Mai, pp.116-120.
Abstract
The simulation of the central solar heating system with seasonal storage has done by using TRNSYS to predict thermal performances and economic aspects. The location of the simulated site is at Glenroy, Melbourne, a southern part of Australia (latitude: 37º 42´ S, longitude: 144º 5´ E, altitude: 97 m.). The meteorological conditions data are prepared by Meteonorm, based on 10 years of measurements. The central solar heating system consist of solar collector, a well-insulated underground seasonal thermal storage tank with heater, fan coil unit that installed in the heating zone and two single speed pump. In the daytime, water from the underground storage tank will feed pass through the solar collector, collecting energy and return to underground storage tank, that will keep the water temperature gradually goes up. In the winter time, and when the indoor house temperature is below 21 ºC, the warm water from the underground storage tank will feed into the house. The heating coil, install in the house, will work as heat exchanger so that energy from water could transfer to an air space in the house to keep the indoor temperature above 21 ºC and the residents may feel comfortable. The sizing of the underground storage tank and also the auxiliary heater capacity are limited by its initial cost and availability, so it will be set as selected parameters. After that, the area of solar collector, initial water temperature would selected by the simulation. The simulation result has shown that, the underground storage tank suitable for this application is around 50 m3 with 5m2 solar collector area. The initial water temperature in the staring of January should be at 50 ºC. The solar factor for this application is 0.76. The economical analysis has shown that the Internal Rate of Return (IRR) of this investment when compare with widely used natural gas heater is around 8.5% that seems to be very economically and favorably.
Keywords: solar heating; underground storage; seasonal storage.