Surendra Kothari

Experimental investigation of energy and exergy efficiencies of domestic size parabolic dish solar cooker

This paper deals with an energy and exergy analysis of a domestic size parabolic solar cooker in actual use. The experimental time period was from 10:00 to 13:30 solar time. During the experiment, it was found that the maximum temperature of water was 368 K. The energy out of the cooker varied between 46.67 and 653.33 W, whereas its exergy output was in the range, 7.37-46.46 W. Maximum energy and exergy efficiencies of the cooker were experimentally evaluated, and it was about 46.82% and 32.97%, respectively. Over the time, both efficiencies were decreased because of the optical and thermal losses from the reflector and pot. By using properly insulated cooking pot, the considerable amount of conventional energy can be saved. Regular use of a solar cooker helps in CO2 mitigation and provides clean and safe cooking.

Experimental investigation of energy and exergy efficiency of masonry-type solar cooker for animal feed

The performance of a masonry animal feed solar cooker was evaluated in terms of energy and exergy. It is a low-cost cooker made of cement, bricks, glass covers and a mild steel absorber plate. The energy and exergy efficiencies of the animal feed solar cooker were experimentally evaluated. The energy output of this cooker ranges from 1.89 to 49.4 kJ, whereas the exergy output ranges from 0.11 to 2.72 kJ during the same time interval. The energy efficiency of the cooker varies between 1.12% and 29.78%, while the exergy efficiency varies between 0.07% and 1.52 % during the same period.

Energetic and exergetic analysis of three different solar cookers

This article deals with the energetic and exergetic analyses, which provides an alternative means of evaluating and comparing the performance of solar cookers. In this experimental setup, three different types of solar cookers have been studied during the typical day from November to January under Indian climatic conditions. The experimental time period was from 09:00 to 14:00 solar time. It was found that the animal feed cooker (AFC), hot box cooker (HBC), and parabolic dish type cooker (PDC) showed maximum energy and exergy efficiencies during the month of November compared to December and January. The energy efficiency of these cookers in November was about 36.74%, 60.94% and 14.45%, respectively, whereas exergy efficiency was 3.62%, 8.71%, 1.41%, respectively. The average energy output of AFC, HBC, and PDC during November was 247.80, 327.60, and 260.40 kJ/day, respectively, whereas the exergy output was 19.02, 33.32, and 21.34 kJ/day, respectively.

Performance evaluation of exhaust air recirculation system of mixed mode solar dryer for drying of onion flakes

This paper deals with the performance of mixed mode type solar dryer for drying onion flakes. During the experiments, no load and full load test were conducted to find out the effectiveness to the system with or without recirculation of exhaust air. The drying and thermal efficiencies and heat utilisation factors were recorded as 21%, 74% and 31% respectively, more compared to recirculation of exhaust air test. The quality of dried onion flakes without recirculation of exhaust air test was superior. The recirculation of exhaust air was founded feasible only with use of desiccant material.

Design theory and performance analysis of paraboloidal solar cooker

A paraboloidal collector having aperture diameter 1.3 m, depth 0.30 m, and focal length 0.35 m was designed and fabricated. The paraboloidal solar cooker was tested under no-load conditions at a recorded maximum temperature of 326°C. The analysis was made from the sensible heating and cooling curves. The values of the overall heat loss factor (F′ UL) obtained from the sensible cooling curve were smaller on different days. The minimal heat loss was due to the wind shield provided at the paraboloidal receiver. Analysis of the sensible heating curve gave the values of the optical efficiency factor (F′ η0). The performance of the paraboloidal collector was determined, and the thermal efficiency was found to be 26%. The performance curve was plotted to predict the approximate time required to boil a known amount of water under given climatic conditions. The solar cooker was found to be useful in cooking a variety of foods.

Cost-benefit and systems analysis of passively ventilated solar greenhouses for food production in arid and semi-arid regions

In this paper, economic feasibility of two vegetable crops (i.e., cucumber and tomato) cultivated in a naturally ventilated greenhouse, and the net present worth, cost-benefit ratio, payback period, and internal rate of return for these crops on year-round cultivation are presented. The cost-benefit ratio demonstrated that growing cucumbers and tomatoes can be economically viable in this climatic region. The present experimental study was conducted in the composite climatic condition of Udaipur (24°35′N, 73°42′E), India. The study area is defined as arid and semi-arid region of Indian climatic conditions. Droughts are a recurring phenomenon in arid and semi-arid regions creating a situation that affects not only agricultural productivity but also people’s health. In particular, the western part of the state is a desert, and its socioeconomic status influences nutrient purchasing power. A poor diet can lead to a vitamin and mineral deficiency. The state of Rajasthan has good agricultural potential; interventions using protected cultivation practices can increase the production and productivity of vegetable crops. However, the current adoption rate of such practices in the state remains very slow, even after a promotional scheme offered by the state government. The government and policymakers should consider offering demonstrations of practices at a larger level. Farmers of the state are marginal and economically poor, requiring more financial assistance. Low cost technologies would be suitable for these farmers.

State of the art on solar drying technology: a review

Solar thermal energy is used in many countries of the world in the agricultural area to conserve agricultural produce and in the industrial sector for drying commercial products. Solar drying is practical, economical and the responsible approach in an environmental point of view. Solar dryers are available in large range of sizes, different design and are used for drying various food and industrial products. It is found that various types of driers are available to suit the needs of end users. This paper deals with a comprehensive review of the various designs, construction and operational principles of the wide variety of practically-realised designs of solar dryer reported previously. Some very recent developments in solar drying technology are highlighted.

Thermodynamic and economic analysis of solar photovoltaic operated vapour compressor refrigeration system

A large number of people in developing countries still live in rural and remote area like India where the grid electricity is yet unavailable or not envisaged by the people. Vaccine preservation has become an important issue and the basic needs in rural areas. Solar power refrigeration is the one of promising option to resolve such burning problem. This paper describes the thermodynamic and economic results of developed solar photovoltaic panels operated 20 litre refrigerator system. No load and full load test were carried out to study the performance of the system. The co-efficient of performance (COP) was observed to decrease with time from morning to afternoon and average COP 3.39 and 3.29 was observed for no load and full load condition, respectively. The exergetic efficiency of both photovoltaic and refrigerator systems were also evaluated for both no load and full load conditions. The overall system energy efficiency was found low because of energy conversion efficiency and exergy efficiency of the photovoltaic system was low. The payback period of the SPV refrigerator was found approximate 6 months.