Performance of two types of coupled solar heater/stills

Abstract

The purpose of this thesis was to study the performance of a solar distillation unit in our local conditions, Malta, 35½°N. The study was specifically done on coupled solar heater/still in conjunction with standard solar stilling devices. The basic criteria chosen was that of obtaining the maximum water production from the least possible area. No economic analysis was attempted since this must be based on a sound knowledge of still characteristics, including local performances for various still design parameters, which at times was not available. This project yielded information on still performances using two different designs; one by coupling a separate heater to a still, the other by including the heater panel within the still itself (see Plate 1). The study consisted of four parts: Part One: the chapters within this part outlined the basic local water supply situation, solar radiation, solar distillation and coupled heater/still concepts. It also included the design and construction of both the solar heater and still used later on for testing purposes. Part Two: this part dealt with the theoretical study performed on a coupled solar heater/still. A computer simulation technique was adopted which yielded hourly, daily and monthly distilled productions, together with the brine temperatures expected. Part three: this involved the testing of the heater and still, separately or coupled together. Experimental procedures, results and interpretations were discussed. Part four: a completely different design to that given in Part One was here treated. The construction, testing and results of this single heater/still unit were outlined. A chapter on its performance on a large scale was also included. The concluding part of this study was based on the various theoretical and practical results obtained for the two still designs considered. It was intended that this study would serve as a basis for further detailed research on the subject as applied to our present local conditions.