Experimental Investigation of the Performance of a Building Integrated Thermal Solar Collector for Domestic Water Heating

Abstract

The recent increased interest in renewable energy has created a need for research in the area of solar technology, particularly solar water heating collectors and systems. In this study a new design of a building integrated thermal (BIT) collector was developed and experimentally tested. The subsequent result of this was the viability of its use in a water heating system for domestic application in a country like New Zealand, can be investigated.

Experimental results showed that the unglazed and glazed collector can achieve thermal efficiencies of 39% and 75%, respectively. A comparison of the glazed BIT with an integrated collector of a similar design showed that the maximum thermal efficiency of 75% was relatively high; however, the downside to this is that high losses also occurred.

A theoretical viewpoint of the collector showed that the improvement in efficiency was attributed to the high fin efficiency which resulted from using a high thermal conductivity material relative to the integrated collector previously studied. Moreover, the high heat loss from the collector was shown to be a result of the lack of side insulation and the presence of air gaps between the collector and the rear insulation, contributing to the overall heat loss from the collector and system.

A control strategy was also developed for the control of the system and simulated tests showed that the controller was indeed effective in controlling the system. However, it was highlighted that an improvement is needed for the method of simulating the load required by the household. Additionally, transient simulation of the developed system showed that accurate predictions of the systems performance can be made. Moreover, using a hypothetical scenario where the heat loss from the BIT collector-system is reduced, it was shown that a significant improvement in its performance for water heating can be made.

This work has shown that the use of integrated collectors for domestic household heating in New Zealand is indeed viable. The potential for the control of these systems to achieve high efficiencies is also recommended, by using advance control strategies.