Performance evaluation of 3-ton solar assisted hybrid refrigeration plant for sub-zero operating temperatures

A 3-ton solar assisted hybrid refrigeration plant for sub-zero operating temperatures has been designed, developed and installed at the Sardar Patel Renewable Energy Research Institute for storing food materials such as fish, meat, butter and cheese. The system, based on a vapour absorption refrigeration cycle, has been designed to operate at a cold-room temperature of – 18°C using steam at a temperature of 150°C. Its performance has been studied in various seasons both under loaded and no-load conditions, and the results are discussed.     

Experience on integration of solar thermal technologies with green buildings

The green buildings of Shanghai Research Institute of Building Science include an office building for the demonstration of public building and two residential buildings, which are for the demonstration of flat and villa, respectively. Here, a solar-powered integrated energy system including heating, air-conditioning, natural ventilation and hot water supply was designed and constructed for the office building. However, only solar hot-water systems were installed for the flat and villa. All the three solar thermal systems have continuously run for 2 years. Two different integrated approaches have been put into practice in the two green residential buildings. It is shown that, for new buildings, solar collectors can be mounted on balconies and awnings besides roofs, on condition that solar systems become part of the general building design. The solar-powered integrated energy system has the advantage of high utilization ratio with different functions according to different seasons. It is testified to be capable of taking on about 70% of the yearly building load regarding the involved space under the weather condition of Shanghai.     

Capital cost and economic viability of thermosyphonic solar water heaters manufactured from alternate materials in India

Many companies in India manufacture solar water heaters but these are not becoming popular in the domestic sector because of their high cost. The Ministry of Non-Conventional Energy Sources (MNES), New Delhi is recommending flat-plate collectors with copper (Cu) risers, headers and plate. Therefore, their cost is high. Long term studies have been carried out at the Central Arid Zone Research Institute, Jodhpur, to reduce the cost by replacing copper tubes with galvanised steel (G.S.) tube and copper plate with aluminium (Al) plate. The aluminium plate is wrapped over the G.S. tube by a special wire wound technique so that good contact of plate with risers and headers has been maintained. In this paper performance and testing of solar water heaters having G.S.–Al fin, Cu–Al fin and Cu–Cu fin in flat-plate collectors have been compared. It has been found that performance of all the three heaters is almost similar. The heater can provide 100 litres of hot water at an average temperature 62.0°C at 4 pm that can be retained to 50.4°C when average tap water temperature was 23.9°C. The efficiency of the heater is 51.9%. The cost of the heater with G.S.–Al collector is only Rs. 8,000.00 while it is Rs. 10,250.00 for solar water heaters with Cu–Cu collectors. The payback period of a solar water heater with G.S.–Al collector has been worked out by considering 10% compound annual interest, 5% maintenance cost, 5%, inflation in fuel prices and maintenance cost. The payback period varies between 2.92 years to 4.53 years depending upon which fuel it replaces. The payback periods are in increasing order with respect to fuels: electricity, firewood, LPG, charcoal, and kerosene.     

Design and development of a solar cooker cum drier

A solar cooker cum drier has been designed and developed. In designing this unit, optimum booster-collector geometry has been considered in order to eliminate the requirement of sun tracking. Tilting arrangements have also been provided to capture more solar energy. This dual purpose device has been found useful for cooking food and dehydrating fruit or vegetables.     

Solar energy education - a viable pathway for sustainable development

The growing consumption of limited reserves of fossil fuels and their impact to the environment have raised global interest in harnessing solar energy. Proper knowledge of solar energy is lacking in many levels of society. Recently, the Energy Research Institute (ERI) of King Abdulaziz City for Science and Technology (KACST) have conducted a survey on the availability of solar energy education program around the world. It has been observed that a considerable amount of work has been done for developing solar energy technologies but relatively little attention has been paid on the role of solar energy education. This paper gives an overview of the current status of solar education program available around the globe and it also highlights the importance of the energy information network for solar education program.     

Thermo-concentration cell: A study on saline water in solar stills

Studies on simultaneous utilization of solar stills as a thermo-concentration cell and as a distillation system have been reported. Cell characteristics have been studied. The electrical energy has been found to increase both with the increase in concentration of sodium chloride (salinity) and the temperature of the saline water. This two way utilization of solar stills has an added advantage that overall utilization efficiency of solar energy is increased against a nominal additional input. For application in rural areas where water needs treatment, (distillation) this extra electrical energy may make it more attractive. The possibility of application of such systems in the industrial sector has also been mentioned.     

An improved solar cooker

An improved hot box type solar cooker (SC-2) has been designed, developed and tested. It is an improvement on the solar cooker SC-1 earlier developed at the institute. The cooking chamber has properly been optimized for cooking the food for a family of five persons. A rubber gasket has been provided at the boundary of the openable door to prevent the leakage of hot air, thus increasing the pressure in the cooking chamber. Different cooking trials like boiling, roasting and baking were successfully conducted and the cooker was found useful from 8.00 a.m. to 5.00 p.m., even during a winter month. The efficiency of the cooker was found to be 41.2 per cent.     

Design optimization of solar cooker

Various designs of solar cookers have been theoretically investigated with a view to optimize their performance. Starting from a conventional box type cooker, various combinations of booster mirrors have been studied to arrive at a final design, aimed at providing a cooker, which can be fixed on a south facing window (for countries of northern hemisphere, mainly situated near the tropic of Cancer). This cooker, with a rear window opening, may provide higher cooking temperature for a fairly large duration of the day. Two or three changes in positions of the side booster mirrors, without moving the cooker as a whole has been proposed. The new design has been experimentally implemented and compared with a conventional box type solar cooker. Besides the convenience of a rear window opening, the cooker provides temperatures sufficiently high to enable cooking two meals a day.     

Design and investigation of a novel concentrator used in solar fiber lamp

A novel concentrator used in solar fiber lamp has been designed and made. The method of the design has been introduced. The lamp has been tested under the real solar condition and the experiment curves have been given. The light transmission will be influenced by the structure of the lamp and the diameter of the fiber, which has been studied in this paper. The experimental results show that the brightness of this solar fiber lamp is about the brightness of a 6-W ordinary electrical energy-saving lamp. The computer simulation for the lamp has been presented and the improvement schemes are proposed.     

Year round performance of a cylindrical solar water heater

A cylindrical collector-cum-storage type solar water heater has been designed, developed and tested. Its year round performance has been carried out and reported in this paper. The heater can provide 50 litres of hot water at 50–60°C in the afternoon and a temperature of 35°C can be retained till the next day for early morning use. The heater receives approximately 30% more radiation as compared to a flat surface. The economics of the heater has been worked out and it has been found that the cost can be recovered within one year.     

On the effects of solar radiation variations on solar heating system performances

The effect of solar radiation availability on the performance of different solar heating systems has been studied. The systems include a solar water heater, passive solar houses and district solar heating systems with seasonal heat storage. Also, different collector orientations and collector types have been investigated. The hourly radiation data were generated by a simple computational simulation procedure. It was found that district solar heating systems with concentrating collectors and passive solar houses showed the largest variations for the given conditions.     

Characterization of black nickel solar absorber coatings electroplated in a nickel chlorine aqueous solution

Black nickel coatings electroplated in a nickel- and sodium chlorine aqueous solution have been prepared and parameters in the process have been optimized to achieve optimal solar selectivity. The best result is a solar absorptance of 0.96 and a thermal emittance of 0.10, as also has been obtained previously for the same type of coating ¹H(¹⁵N, αγ)¹²C nuclear resonance reaction (NRR) have contributed with new information about surface chemical composition, morphology and atomic composition in depth profile. These investigations reveal that the coating is porous and contains mainly metallic nickel at the substrate–coating interface and mainly nickel hydroxide at the front surface.The stability of the coating has been tested regarding high-temperature and condensation at high humidity. It has been found that the solar absorptance changes initially, during the first hour of exposure at high temperature, but will then stabilize. Condensation causes a more severe attack on the coating by cracking it. This is contradictory to the results from previous tests at high temperature and humidity in which the black nickel coating was found to be resistant     

Further studies on double solar still

This paper is devoted to the development of a transient model of the performance of a double solar still and its validation by experiments. the dependence of the daily output of the distillate on wind velocity, ambient temperature and daily insolation has been studied analytically. It is seen experimentally that the presence of a black dye in the lower basin increases the distillate output by 10 to 15 per cent.     

Experimental investigation of a solar energy heating system under the climatic conditions of Edirne

Seasonal storage of solar energy to supply the heat requirement of buildings in Edirne (41°39′54″N) has been examined experimentally. Solar energy has been stored in a cylindrical underground storage unit. Measurement values have been recorded per hour by means of a computerized recorder between July 2005 and May 2006. Monthly average temperature values of the heat storage unit and the surrounding ground have been calculated through the measurement results. The transient heat transfer which takes place between the heat storage unit and the surrounding ground has been calculated by means of the QuickField finite-element analysis program. It has been determined that the most significant deviations between the theoretical and the experimental temperature values turn out to be in question during the heating period. The annual solar fraction of the solar energy heating system has been determined as 53% for space heating and 85% for domestic water heating.     

Effect of Temperature Dependent Internal Heat Transfers on the Performance of a Solar Still

In this paper, an effect of the temperature dependence of internal heat transfer coefficients on the performance of a single basin solar still has been studied by incorporating the change of water mass in the basin with time, initial basin water temperature etc. On the basis of numerical calculations based on simple transient analysis, the following conclusions have been drawn:

i) the evaporative heat transfer coefficient is a strong function of brine temperature, and

ii) the change of brine mass with time has insignificant effect on the performance of the still in nocturnal production which is in accordance with the assumption made by Malik and Tran (1973). This is true for other cases also.

These have also been validated by experimental results.     

Solar air heater applications in India

Solar air heaters of many types have been developed in India and their performance studied in detail. The application of these air heaters are limited to a few demonstration projects for food dehydration, and space heating. Some of these case studies are described in this paper. For a few cash crops, the potential of solar air heaters for the drying process has been assessed in detail. Space heating by solar air heaters and their use for natural ventilation has also been discussed and results of a theoretical study presented to make out a case for more intensive research in the fields of solar air heater applications in India.     

Solar chimney power plants for high latitudes

A solar chimney system for power production at high latitudes has been designed and its performance has been evaluated. A mathematical model and a code on MATLAB platform have been developed based on monthly average meteorological data and thermodynamic cycle. The thermal performance of a 5 MW nominal power production plant at three locations in Canada, namely Ottawa, Winnipeg and Edmonton, is studied. The sloped collector field is built at suitable mountain hills, which also functions as a chimney. Then a short vertical chimney is added to install the vertical axis air turbine. The results showed that solar chimney power plants at high latitudes may have satisfactory thermal performance and produce as much as 85% of the same plants in southern locations with horizontal collector field. The overall thermal performance of these plants is a little less than 0.5%.