Enhancing photovoltaic efficiency through evaporative cooling and a solar still

The efficiency of photovoltaic panels decreases with the increase in panel temperature while converting light into electricity. The issue of temperature rise and the associated decrease in efficiency has been widely analysed by active and passive cooling methods. In those processes, normally water is used as a cooling medium, and it results in water loss along with power loss due to circulating or compensating for the lost water. The current study aims to address both efficiency as well as water loss by combining an evaporative cooling technique with a solar still. A Photovoltaic panel with rear-side evaporative cooling is attempted by using a jute sack dipped in water at both ends. As a result of capillary action, the water from a solar still rises through the sack and cools the panel’s rear side. Solar still operation is ensured by an extended portion of glass. During desalination, the evaporated vapour from the solar still condenses on the back cover of the glass surface and is collected in a collection trough. As a result, the output power increased by 5.6 % and the electrical efficiency increased by 14.51 % and the surface temperature are reduced by 8°C. After seven hours of sunshine, the proposed PV panels and solar still system produced approximately 550 ml of water

Efficiency Investigation of An Enhanced Air Heater Used In A Humidification-Dehumidification Desalination System

Background: Humidification dehumidification (HDH) desalination was proved to be economical for producing potable water. But there was a need to increase the productivity of the (HDH) desalination systems. Objective: This paper presents performance of the enhanced air heater in the (HDH) desalination system with the experimental and theoretical analysis. Experiments were conducted with the half perforated circular inserts arranged in series with different orientation angles (β=45º, 90°, 180º), pitch ratios (PR=1.5, 3) and different air mass flow rates (14 to 21 kg/h) in the air heater. Results: Maximum productivity of 850 ml/h in the HDH desalination system is obtained for an air heater's exergetic efficiency of 96% with baffle settings of 180 º orientation and pitch ratio of 1.5 with an air mass flow rate of 14 kg/h. Conclusion: Exergetic efficiency of the air heater progressively increases with the reduction in pitch ratio, increase in orientation angle between the plate and decrease in mass flow rate of air supplied to the unit

Performance characteristics of a glowplug assisted low heat rejection diesel engine using ethanol

Conventional diesel engines with ethanol as fuel are associated with problems due to high self-ignition temperature of the fuel. The hot surface ignition method, wherein a part of the injected fuel is made to touch an electrically heated hot surface (glowplug) for ignition, is an effective way of utilizing ethanol in conventional diesel engines. The purpose of the present study is to investigate the effect of thermal insulation on ethanol fueled compression ignition engine. One of the important ethanol properties to be considered in the high compression ratio engine is the long ignition delay of the fuel, normally characterized by lower cetane number. In the present study, the ignition delay was controlled by partial insulation of the combustion chamber (low heat rejection engine) by plasma spray coating of yttria stabilized zirconia for a thickness of 300 [mu]m. Experiments were carried out on the glowplug assisted engine with and without insulation in order to find out the possible benefits of combustion chamber insulation in ethanol and diesel operation. Highest brake thermal efficiency of 32% was obtained with ethanol fuel by insulating the combustion chamber. Emissions of the unburnt hydrocarbons, oxides of nitrogen and carbon monoxides were higher than that of diesel. But the smoke intensity and was less than that of diesel engine. Volumetric efficiency of the engine was reduced by a maximum of 9% in LHR mode of operation.Low heat rejection Ethanol Glowplug Diesel engine Alternate fuel Ceramic coating

Performance analysis of solar stills based on various factors affecting the productivity--A review

Although, more than two-thirds of the Earth is covered by water, shortage of potable water is a serious issue that many countries suffer from. Furthermore, the worldwide rapid growth of industry and population has resulted in a large boom in demand for fresh water. The solar still, in many respects, is an ideal source of fresh water for both drinking and agriculture; it is one of the most important and technically viable applications of solar energy. There are many types of solar still; the simplest and most proven is the basin type. Investigations showed that the basin-type solar still has been found to be of limited performance. Numerous experimental and numerical investigations on basic types of solar still have been reported in various literatures. An extensive review for solar desalination systems has been carried out in this paper.Solar still Desalination Productivity Water-glass temperature difference Mini solar pond

Numerical investigation on cooling performance of oil cooled PMSM jacket design with vertical straight fin design

Cooling has been an important parameter to extend the high-speed generator operating conditions. Literature highlights the high speed generator jacketjacket of generator is a crucial part that need to be cooled down to dissipate the coil temperature to ensure the performance of the Permanent magnet synchronous machine (PMSM). Research shows there are work done on the internal jacket design to improve cooling. This research work focuses on further enhancement of more design parameters for the internal oil flow jacket space design to dissipate heat better. The vertical straight fin configurations were deployed to investigate the effect of heat transfer with same cooling medium, Oil. The numerical analysis using ANSYS-FLUENT was completed, converged and mesh independent results were presented. The vertical straight fins improve heat transfer more than triple as compared to the baseline. This will be used as base for future enhancement in PMSM jacket cooling for high speed generator

Experimental investigations on mixing of two biodiesels blended with diesel as alternative fuel for diesel engines

The world faces the crises of energy demand, rising petroleum prices and depletion of fossil fuel resources. Biodiesel has obtained from vegetable oils that have been considered as a promising alternate fuel. The researches regarding blend of diesel and single biodiesel have been done already. Very few works have been done with the combination of two different biodiesel blends with diesel and left a lot of scope in this area. The present study brings out an experiment of two biodiesels from pongamia pinnata oil and mustard oil and they are blended with diesel at various mixing ratios. The effects of dual biodiesel works in engine and exhaust emissions were examined in a single cylinder, direct injection, air cooled and high speed diesel engine at various engine loads with constant engine speed of 3000 rpm. The influences of blends on CO, CO2, HC, NOx and smoke opacity were investigated by emission tests. The brake thermal efficiency of blend A was found higher than diesel. The emissions of smoke, hydro carbon and nitrogen oxides of dual biodiesel blends were higher than that of diesel. But the exhaust gas temperature for dual biodiesel blends was lower than diesel

An experimental investigation on diesel and low heat rejection engines with dual biodiesel blends

In this article, the effects of thermal barrier coated combustion chamber on the single cylinder direct injection diesel engine with dual biodiesel (combination of pongamia pinnata oil and neem oil) are experimentally investigated. The piston surface an

Numerical analysis of oil cooled PMSM jacket with horizontal strips design

Cooling has been an important parameter to extend the high speed generator operating condition. Literature highlights the jacket of generator is a crucial part that need to be cooled down to dissipate the coil temperature to ensure the performance of the Permanent magnet synchronous machine (PMSM). Research shows there are work done on the internal jacket design to improve cooling. This research work focus on more design parameters for the internal oil flow jacket space design to dissipate heat better. The horizontal strips with straight and angled configurations were deployed to investigate the effect of heat transfer with constant cooling medium, Oil. The numerical analysis using ANSYS-FLUENT was completed, converged and mesh independent results were presented. The innovation in horizontal strips has shown to improve in heat transfer rate more than double form the bassline design. This will be used as base for future investigation for jacket cooling for high speed PMSM

Productivity enhancement of stepped solar still: Performance analysis

Maintaining minimum depth in conventional basin type solar still is difficult, as the area is large. However this can be achieved in stepped solar still in which the area of the basin is minimized by having small trays. Very few works have been carried so far in stepped solar still and constant depth trays are used in the basin plate. In this work, a stepped still with two different depth of trays are used. The basin plate contains twenty five trays with 10 mm depth and twenty five trays with 5 mm depth. To improve the productivity, experiments were carried out by integrating small fins in basin plate and adding sponges in the trays. Theoretical and experimental analyses are made for fin type, sponge type, and combination of fin and sponge type stepped solar still. When the fin and sponge type stepped solar is used, the average daily water production has been found to be 80% higher than ordinary single basin solar still. The theoretical results agree well with the experimental. Also an economic analysis was made. The payback period of this setup is 400 days

Study on stepped type basin in a solar still

In this work a stepped solar still is used to enhance the productivity of the solar still. The concept of integrating the stepped solar still along with inclined flat plate collector is introduced in this research work. In this stepped type solar still, a conventional basin of area 1 m2, was placed at the bottom. Another absorber plate, stepped type was fixed on the top of the conventional basin. It consists of subsequent trays and inclined flat plate collectors. This ensures an additional exposure area which augments the evaporation rate. Experiments were conducted with various depths in the conventional basin. A conventional still was fabricated and run parallel with the experimental set up for comparison. Sensible heat storage mediums such as rocks, pebbles were added to the top basin of stepped trays and bottom conventional basins to increase the temperature of water in the still. Wicks were placed on the inclined flat plate collector to augment the evaporation rate due to capillarity. A higher evaporation rate is obtained in the packing material with wicks and pebbles in tray combinations. Theoretical analysis was performed and it agrees with experimental values. Efficiency of the system was also compared with conventional solar still