Solar Cooler Research Articles

Evaluation of Storage Stability and Quality Changes of Fish Muscle (Pangasianodon hypothalamus) Preserved in Fabricated Portable Solar Cooler and Domestic Refrigerator

Background: This study was carried out to evaluate the quality changes and storage stability of fish muscle (Pangasianodon hypothalamus) preserved in fabricated portable solar cooler and domestic refrigerator. Methods: Fish muscle from Pangasianodon hypothalamus were studied, keeping it in a fabricated portable solar cooler and in a domestic refrigerator at 5°±1°c to compare the shelf-life and quality of fish muscles. The fish muscles were packed separately in LDPE (low density polyethylene) packets and stored in a solar cooler and domestic refrigerator up to 7 days to compare the different physico-chemical, microbiological and sensory parameters on 0th , 3rd and 7th day. Results: The results revealed that there were no significant changes (P greater than 0.05) of different parameters during the storage periods in compare to solar cooler and domestic refrigerator. Finally, from the present study it can be concluded that the preservation of fish in a portable solar cooler system is thus economically suitable, feasible and acceptable up to 7 days as compared to domestic refrigeration method at controlled temperature.

Effect of dragon fruit peel powder on quality and acceptability of fish nuggets stored in a solar cooler (5 ± 1°C).

Fish nuggets were prepared with dragon fruit peel powder (1.0, 1.5 and 2.0% w/w) to evaluate its quality and improvement in shelf-life during 15days storage in a prefabricated solar cooler (5 ± 1°C). Antioxidative and antimicrobial effects of dragon fruit peel powder in fish model system were also evaluated during storage. Results showed that dragon fruit peel is a good source of dietary fibre (59.8%) and phenolic compounds [65.7mg Gallic Acid Equivalent (GAE)/100g of sample] and contained 6.03% protein, 6.14% fat and 4.34% ash. Use of dragon fruit peel powder significantly (p < 0.05) improved the emulsion stability and cooking yield and nuggets with peel powder had lower pH value than control. Fish nuggets with peel powder showed gradual decrease (p < 0.05) in hardness, springiness, cohesiveness, gumminess and chewiness with advancement of storage period. Nuggets with 1.5% dragon fruit peel showed better sensory attributes compared to the others. Dragon fruit peel powder significantly inhibited (p < 0.05) the lipid oxidation and microbial load in fish nuggets during the storage period. So, it can be concluded that dragon fruit peel powder may be used as antioxidant dietary fibre for improved quality and acceptability of fish nuggets in prefabricated solar cooler. 1.5% level of incorporation showed better results in terms of antioxidant activity and better shelf-life of the fish nuggets.

Comparison of the efficiency of solar-powered prototype vapour compression cooler with evaporative charcoal cooler in maintaining quality of French beans

The quality and shelf life of French beans is affected by the time of harvesting and storage period. Cooling immediately after harvesting is important. The use of a solar evaporative cooling system is suitable for use in rural areas with no power grid connections. This study compared evaporative charcoal cooler and solar cooling systems on improving the quality and shelf life of French beans. The prototype was made using mathematical modeling equations and was powered by solar power while the evaporative charcoal cooler was made from iron sheets with charcoal walls. Freshly harvested French beans were stored under the two cooling systems. The weight and temperature of the stored produce were checked hourly. At the end of the day, produce was packed into modified atmosphere packaging (MAP) bags and stored for 7 days in a cold room. After seven days, oxygen and carbon dioxide levels were measured using a Bridge gas analyzer. The results show significant differences in weight loss between produce stored in evaporative charcoal shed and solar cooler prototype with those stored in evaporative charcoal cooler having 5% weight reduction while those solar coolers having 3% weight loss. A higher accumulation of CO2 was realized in the evaporative charcoal cooler than in the solar-powered cooler. The solar-powered cooler maintained weight, reduced the temperature of products, and maintained the balance between carbon dioxide and oxygen thus reduction in metabolic activities. This enhanced the shelf life and quality of the produce.

English

The quality and shelf life of French beans can be affected within hours of harvesting if the produce is not cooled after harvest. Solar-powered cooling systems are suitable for use in rural areas that are not connected to the grid. This study aimed at developing a solar powered cooling system to improve the quality of French beans in smallholder farms in Kenya. Freshly harvested French beans were stored under conventional field shed conditions and a solar-powered prototype cooler, after which weight and temperature were measured at intervals of 2 h and later packed in modified, atmosphere packaging bags. The bags were stored for 7 days in a cold room. Accumulated gas levels of oxygen and CO2 in the packaging bags were measured at the end of the shelf life. Significant differences (P≤0.05) in weight loss between produce stored in the conventional shed and those in the solar cooler prototype were observed. The weight of French beans reduced by 5 and 2.8% after 7 h under a conventional field shed and a fabricated solar cooler respectively. The volume of CO2 and O2 released from produce stored in a conventional shed and those in a fabricated solar cooler prototype were significantly different (P≤0.05). Key words: Conventional cooling method, French beans, temperature, solar cooler, weight loss.

Effect of cooling in a fabricated solar cooler on histology of Pangasius (Pangasianodon hypothalamus) muscle

Effect of cooling in a fabricated solar cooler on histology of Pangasius (Pangasianodon hypothalamus) muscle

Analysis of a Direct Current Compressor for Solar Cooler

Refrigeration systems have higher electricity consumption ratio in overall energy consumption especially in household utilization. On the other hand, these systems have an advantage of being powered by renewable energy sources such as solar or solar-wind hybrid systems because of their lower power demand. Since the efficiency improvement of refrigeration systems is crucial for domestic and industrial systems in the present study, solar energy powered compressor for vapour compression refrigeration systems have been investigated. Compressor is the most important part and often the costliest component of any refrigerant system. There are two different options for powering the compressor such as alternative current (AC) and direct current (DC).For that reason, this study focused on thermal analysis of critical component inside the novel DC compressor. Computational Fluid Dynamics (CFD) analysis has been realized to figure out the heat transfer mechanism inside the compressor components and also thermodynamics efficiency. Temperature distribution in the compressor during the operation was presented and the component of the compressor position re-designed with resulted parameter and discussed affects of the volumetric efficiency.Furthermore, in this study, experimental performance analysis of the novel DC type refrigeration compressor implemented in a 50 l refrigerator to show its cooling performance and compare well known DC compressor in the market. Energy usage reduction and operational improvement potential of the solar powered DC compressor via variable speed operation were investigated. The comparison showed that variable speed operation of the novel DC compressor can be much more efficient than constant speed operation.

Improving Performance of Solar Cooler by Using Nozzles

Improving Performance of Solar Cooler by Using Nozzles

Three adsorbers solar cooler with composite sorbent bed and heat pipe thermal control

Abstract Three adsorbers solar cooler was experimentally investigated. Ammonia was chosen as a working fluid. Two adsorbers (twins) were filled with the same complex compound (activated carbon fiber with MnCl 2 microcrystals on the filament surface). The third low temperature adsorber has second complex compound (activated carbon fiber with BaCl 2 microcrystals on the filament surface). The cycle of physical adsorption and chemical reactions in the sorbent bed of adsorber was followed by condensation/evaporation of ammonia inside the pores. This combination of adsorption/condensation and evaporation/desorption is a novelty of cooler design, which increases the heat and cold generation in adsorber. The specific feature of third adsorber is the time of its cold generation. This time includes the liquid evaporation and desorption/regeneration time of ammonia in the sorbent bed. The cooler thermal management is based on heat pipes. The solar heating is a source of energy for cooler. The sink of the cold is the air flow.

Solar cooling with aluminium pillared clays

Aluminium modified clays were prepared, characterised and tested for their potential application as solar coolers of roof surfaces. The water adsorption isotherm of the samples with restored cation exchange capacity was of hydrophilic type II, indicating multilayer adsorption with large heat of adsorption and pore condensation of water vapour at the pressures of the proposed application. In addition, high moisture adsorption capacity (more than 0.1 g of moisture per g of material at 60–70% of relative humidity) and fast kinetics for night sorption (comparable to silica gel) were determined for the freeze-dried pillared sample. In cyclic experiments with low irradiation during the day and night relative humidity of 55%, the maximum temperature inside the pillared montmorillonite was 6.5 °C lower than the corresponding temperature inside a typical soil sample. The primary mechanism for the reduced temperature elevation at aluminium modified clays was evaporative cooling and desorption with minor influence of solar reflection. These results indicate the suitability of aluminium pillared clays for lowering the roof surface temperatures.

The modelling and potential applications of a simple solar regenerated grain cooling device

Abstract Cooling stored grains is an effective method of slowing the growth of populations of pest insects and maintaining desirable properties of the grains, such as seed viability. In temperate and sub-tropical climates, ventilation or aeration with ambient air at night usually results in reducing the wet-bulb temperature of the intergranular air, and this has a beneficial effect on storage. However, the relative humidity of ambient air at night is usually high, and this limits its cooling capacity. This paper describes a device that reduces the humidity of ambient air almost isothermally, and which therefore enables grain to be cooled to lower temperatures than those attainable using ambient air. The grain cooling device is simple to build using readily available materials, and requires only sheet metal working skills for its fabrication. Furthermore, the energy consumption of the device is very low and it uses solar energy to regenerate beds of desiccant. A mathematical model of the device is presented which enables the heat and mass transfer processes that occur in the device to be studied in detail. The model is validated against previously published experimental results. It is indicated that when operating in a subtropical climate the cooling device is capable of reducing the wet-bulb temperature of ambient air from about 17.3°C to about 12.3°C. Under these conditions the cooling device provides typically 50 times more cooling energy than electrical energy consumed. The model demonstrates that the degree of grain cooling that is possible decreases with increasing air flow rate, but the quantity of grain that can be cooled increases. The model is used to explore the effects of aerating grain with air conditioned by the solar cooler on insect population growth, the rate of pesticide decay and seed viability.

Performance of a flat-plate solar collector

The design of a simple solar collector made from corrugated, galvanized-iron sheet is given. Its performance during summer at Allahabad, India, at various flows is presented. To obtain hot water at temperatures higher than 170 deg F, temperature being averaged over an eight-hour period, a flow of only about 1 lb/hr-ft 2 should be allowed. The supply of hot water from the collector will be used in an absorption-type solar cooler.