Preliminary analysis of systems for integrating solar thermal energy into processes with heat demand

Abstract

Abstract The aim of this work was to develop a method for preliminary evaluation of the ratio between the investment and amount of solar thermal energy, integrated into processes with heat demands. A targeting method has been developed for maximising the amount of integrated thermal energy collected by the required size of solar collector surface area, as well as the size of heat storage. The size of the solar collector area and the heat storage is based on the number of consecutive sunny days and shady days. In the first step the data of the heat demands were collected that could be potentially satisfied from solar sources. In the second step the amount of heat per surface area unit was determined as gained during sunny days (area-specific heat). The collector system and geographical characteristics were taken into account when determining the amount of heat gained. The temperature driving forces were taken into account for heat exchanges between the solar collector medium and storage, and also between the storage and process demands. The required collector surface area has been defined as the heat demands for the sunny and shady days together divided by the product of the area-specific heat of a given collector and the number of sunny days at a given geographical location. The proposed targeting method can be applied for the pre-screening of alternatives in order to eliminate economically non-viable solutions before performing more detailed system synthesis. An illustrative case study has been performed in order to evaluate the applicability of the developed method.