ECONOMICS OF SOLAR AIR PREHEATING IN SOUTH INDIAN TEA FACTORIES - A CASE-STUDY

Tea processing is an energy intensive operation requiring both thermal and electrical energy. Hot air at a temperature of 100-130 degrees C for tea drying and withering has been obtained in the past by burning coal or firewood. Over the last four years, roof integrated solar air heating systems have been introduced in some of the tea factories of s outh India, as a partial energy source. This paper aims to present the economical analysis of one such system: a 212m(2) collector area syst em that has been in operation for 2.75 yr. The system has reduced spec ific fuel, consumption for tea production from 0.932 to 0.71 kg/kg dmt (drier mouth tea), which represents a fuel savings of approximately 2 5%. The economic analysis considered the annual investment cost and re turn cost and included concessions offered by the Government. It shows a payback period of from two to four years, depending upon whether th e company is profit making or non-profit making. This work has helped to establish the economic viability of this method. (C) 1998 Elsevier Science Ltd. All rights reserved.