Energy and carbon emission savings in Spanish housing air-conditioning using solar driven absorption system

Abstract

Air conditioning (AC) is spreading in Spain, where summer weather reaches temperatures above 35 °C. This causes the increase, not only of electricity consumption, but also organic refrigerant leakage due to the use of vapour-compression machines.

An experimental research on solar absorption cooling has been carried out at Universidad Carlos III de Madrid (UC3M) in order to evaluate alternative lower impact AC techniques. The facility is based on an on-Campus field of 50 m2 flat plate solar collectors driving a single-effect commercial LiBr/H2O absorption machine through a hot-water storage tank.

Experimental operating parameters have been recorded during 2004 summer season in periods of 10 min showing all the relevant figures of merit.

Results show that absorption machine cooling power reaches 6–10 kW, with a generator driving power input of 10–15 kW, achieving a mean cooling period of 6.5 h of complete solar autonomy on a seasonal average day.

In order to measure the market applicability of this setup, the instantaneous thermal load and demand of a single detached housing of total floorspace of 90 m2 were calculated using standard techniques. Its peak ranged from 6 to 8 kW. Seasonal solar fraction of AC provided by the facility reached 56%.

This work shows results on system performance, economic investing, energy and economic savings and includes environmental impact reduction, when comparing the solar absorption system with a conventional vapour-compression machine. A sensitivity study to solar field size has been performed to yield the reasonable share of the absorption machine in the seasonal cooling demand. The result indicates that the dimensioning of the facility is correct.