Kiran Deshpande’s scientific contributions

Industrial process heating has been identified as a potential field for solar thermal applications. In this paper, a comparative study was carried out on the performance of an individual solar collector under laboratory conditions and performance of the collector array under field condition. Compound Parabolic Concentrator (CPC) has been used as a solar collector for the application of boiler feed water preheating. The characterization of CPC has been done in liquid phase with water as a working fluid as per the standard, IS 16648 (Part-5):2017. The optical efficiency of the CPC is found to be 64.8% under standard test conditions. In the field, total 200 number of CPCs, each having 3 m² area, were installed. The performance monitoring and evaluation of the actual installation was carried out over a period of 10 months. The system was designed to supply average 448,500 kWh- Thermal/year, saving the equivalent amount of fossil fuel. The comparative study of the performance of CPC collector under standard conditions and actual operating conditions in the field shows significant variation. The average variation in the performance was about 9% with a maximum variation of 14.7%. The major reasons behind the lower performance output than expected, attribute to the heat losses through the collector manifold and piping (3.9%), soiling of reflector and absorber of CPC (1.72%), uncertainties of instruments (1.49%) and other unaccounted losses like dislocation of the evacuated tubes from the original position, loss of vacuum through evacuated tubes, shadow effect, heat utilization pattern etc. (1.89%), which should be considered while designing the solar field to meet the required output.

Comfort cooling using solar energy can be done using two types of technologies viz; vapor compression machines (VCM) operating on electricity and vapor absorption machine (VAM) operating on thermal heat. Both technologies are used in industrial process and commercial establishments. In present article, the utilization of solar thermal energy for cooling purpose in commercial and industrial establishments has been discussed. A complete case study based on integration of solar thermal energy system for cooling with the existing system has been studied along with its performance evaluation. Among the various available solar thermal technologies, Scheffler dish technology has been used for generation of heat required for operating VAM. The existing electrical VCM system acts as a backup during non-sunny hours. The Scheffler dish technology can generate required heat for double effect lithium-Bromide (Li-Br) vapor absorption machine. The size of solar installation and VAM capacity can be decided depending on the available area and the required cooling load. The annual saving of approximately 1,20,000 units of electricity and reduction of 113 Metric Tons of CO2 emission was achieved using 320 m 2 of Scheffler dish collector area with a payback period of 6-7 years. The present case study revealed that the solar thermal cooling based vapor absorption machine can be seamlessly integrated with the existing electrical chillers for comfort cooling applications.

There is a huge potential to deploy solar thermal energy in process heat applications in industrial sectors. Around 50 % of industrial heat demand is less than 250 °C which can be addressed through solar energy. The heat energy requirement of industries like automobile, auto ancillary, metal processing, food and beverages, textile, chemical, pharmaceuticals, paper and pulp, hospitality, and educational institutes etc. can be partially met with solar hybridization based solutions. The automobile industry is one of the large consumers of fossil fuel energy in the world. The automobile industry is major economic growth driver of India and has its 60 % fuel dependence on electricity and remaining on oil based products. With abundant area available on roof top, and need for medium temperature operation makes this sector most suitable for substitution of fossil fuel with renewable solar energy. Auto sector has requirement of heat in the temperature range of 80-140 oC or steam up to 2 bar pressure for various processes like component washing, degreasing, drying, boiler feed water preheating, LPG vaporization and cooling. This paper discusses use of solar energy through seamless integration with existing heat source for a few processes involved in automobile industries. Integration of the concentrated solar thermal technology (CST) with the existing heating system is discussed with a case study for commonly used processes in auto industry such as component washing, degreasing and phosphating. The present study is undertaken in a leading automobile plant in India. Component cleaning, degreasing and phosphating are important processes which are carried out in multiple water tanks of varying temperatures. Temperatures of tanks are maintained by electrical heaters which consumes substantial amount of electricity. Non-imaging solar collectors, also known as compound parabolic concentrators (CPC) are used for generation of hot water at required process temperature. The CPC are non-tracking collectors which concentrate diffuse and beam radiation to generate hot water at required temperature. The solar heat generation plant consists of CPC collectors, circulation pump and water storage tank with controls. The heat gained by solar collectors is transferred through the storage tank to the process. An electric heater is switched on automatically when the desired temperature cannot be reached during lower radiation level or during non-sunny hours/days. This solar heating system is designed with CPC collectors that generate process heating water as high as 90OC. It also seamlessly integrates with the existing system without compromising on its reliability, while reducing electricity consumption drastically. The system is commissioned in April, 2013 and since then it has saved ~ 1,75,000 units of electricity/year and in turn 164 MT of emission of CO2 annually.