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Collector Efficiency by Single Pass of Solar Air Heaters with and without Using Fins

Collector Efficiency by Single Pass of Solar Air Heaters with and without Using Fins

In this paper, the heat exchanges in a Plexiglas cover solar air heater are analyzed and an explicit expression of the temperature of the air flowing in that collector is developed as a function of the space coordinate in the flow direction and the time dependent solar intensity. Then the effects of various parameters such as the inlet air temperature, the distance between the absorber and the transparent cover and the air flow on the dynamic behavior of the collector are studied. The solar air collectors were tested and their performance was compared. The efficiency depends significantly on the mass flow rate, the solar irradiation and surface geometry of the collectors. The efficiency of the collector improves with increasing solar intensity and mass flow rate both 0.012 and 0.016 kg/s, due to enhanced heat transfer to the air flow. The condition of weather affects the mass flow rate on heat transfer. The efficiency of the solar air collector is proven to be higher. The highest collector efficiency and air temperature rise were achieved by the finned collector with an angle of 45°, whereas the lowest values were obtained from the collector without fins. The efficiency of the solar air collectors depends significantly on the solar radiation and surface geometry of the collectors and the fins on the back of the absorber plate account for the mass flow rate.
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Investigating the collector efficiency of silver nanofluids based direct absorption solar collectors

Investigating the collector efficiency of silver nanofluids based direct absorption solar collectors

The application of a nanofluid as the working fluid of a DASC is a relatively new concept in the last decade [12,13], which was first demonstrated by Tyagi et al. [14]. Nanoparticles (NPs) dispersed in a base fluid offer the potential to improve the optical properties of nanofluids, which could lead to an increase in the collector efficiency due to the absorption and scattering of NPs. Additionally, it has been shown that the addition of NPs has a dramatic effect on the base fluid’s thermophysical properties such as the thermal conductivity, mass diffusivity, and viscosity [15-20]. Compared with the base fluid, the enhanced optical and thermophysical properties of a nanofluid allow it to be a working medium applied in different solar collectors [21,22]. Tyagi et al. [14] revealed that under similar operating conditions, the efficiency of a DASC using nanofluids as the working fluid was up to 10% higher than that of a flat-plate collector. In addition, they also observed that the presence of NPs increased the absorption of solar energy by more than nine times compared to that of pure water. Many recent studies have indicated that the selection of the nanofluid is very important to obtain a performance enhancement in a DASC. A carbon nanotube/water nanofluid was applied as a working fluid in low-temperature DASCs by Karami et al. [23]. The extinction coefficient and thermal conductivity of the functionalized carbon nanotube nanofluid showed remarkable improvement compared to the base fluid, even at low particle loadings. Its promising optical and thermal properties, together with the appropriate stability, make it very interesting for increasing the overall efficiency of low-temperature DASCs. The extinction coefficient of a water-based aluminum nanofluid with a varying NP size and volume fraction was investigated and evaluated by Saidur et al. [24]. The particle size had a minimal influence on the optical properties of the nanofluid. Moreover
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Solar collector efficiency testing unit

Solar collector efficiency testing unit

This project concentrates on the development and testing of the solar efficiency unit. This was achieved by defining the capabilities of the system, and developing a control strategy to control the temperature and flow rate of the fluid leaving the unit. The prime objective was to develop the unit’s control performance to fulfil the ‘Australian and New Zealand Standard AS/NZS 2535.1.2007’ for testing the efficiency of solar collectors. This will enable the system to perform multiple tests a day, with a high level of accuracy. The AS/NZS 2535.1.2007 standard suggests that the fluid’s flow-rate and temperature at the outlet of the unit should have an accuracy of ±1% and ±1°C respectively throughout the duration of the test, which is 15 minutes.
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Calculation and Fabrication of a Solar Flat Plate Collector Efficiency using Mild Steel as Absorber Plate

Calculation and Fabrication of a Solar Flat Plate Collector Efficiency using Mild Steel as Absorber Plate

The solar thermal energy is collected by a device called solar collector. A flat plate collector is such type of solar thermal collector which is using in such place where moderate heat is require. It can increase the temperature of the fluid up to 1000C above ambient temperature. Flat plate collector (FPC) is a special kind of heat exchanger that transforms solar radiation energy in to heat energy which is transferred through a working liquid. Different absorber material and thickness. Analysis will be done to obtain the FPC efficiency between mild steel mild steel material heat absorber plate.
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Solar collector efficiency testing unit

Solar collector efficiency testing unit

This project concentrates on the development and testing of the solar efficiency unit. This was achieved by defining the capabilities of the system, and developing a control strategy to control the temperature and flow rate of the fluid leaving the unit. The prime objective was to develop the unit’s control performance to fulfil the ‘Australian and New Zealand Standard AS/NZS 2535.1.2007’ for testing the efficiency of solar collectors. This will enable the system to perform multiple tests a day, with a high level of accuracy. The AS/NZS 2535.1.2007 standard suggests that the fluid’s flow-rate and temperature at the outlet of the unit should have an accuracy of ±1% and ±1°C respectively throughout the duration of the test, which is 15 minutes.
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An experimental investigation of performance of a 3-D solar conical collector at different flow rates

An experimental investigation of performance of a 3-D solar conical collector at different flow rates

The efficiency variations of solar conical collector versus inlet-ambient difference temperature are shown in Fig. 9. In this figure the efficiency has nonlinear behaviour and by increasing in the inlet-ambient difference, the collector efficiency will decrease. This trend can be explained with the Eq. (4). In this equation the big value of the difference between inlet and ambient temperature means that the collector energy losses are big so the collector efficiency will be increase. Besides, in the current study on conical collector, in 0.35-2.8 lit/min flow rates, the pressure drop has been more than 5 kPa. These values of pressure drops was about 2.8 times that of values in Alim et al. [31] and Ko et al. [36] studies. Fig. 10 shows that the experimental data are fitted with linear equations to calculate the characteristic parameters of the solar conical collector at different flow rates.
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An Experimental Study of Solar Tunnel Dryer for Drying Onion Slices (ALLIUM CEPA, L.)

An Experimental Study of Solar Tunnel Dryer for Drying Onion Slices (ALLIUM CEPA, L.)

experiment with in six days air velocity was varies .53 to 1.22 m/s and average relative humidity was varies 46 to 53 % and exhaust fan speed was constant during this study that means it was 500 rpm. The average temperature inside solar tunnel was varies 54 to 59 ˚c. Finally moisture content in onion slices was 10 % and it’s observed that relative humidity decrease with increase temperature and moisture content also decrease. Collector efficiency was varied from 45% to 55%.

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Determining the effect of inlet flow conditions on the thermal efficiency of a flat plate solar collector

Determining the effect of inlet flow conditions on the thermal efficiency of a flat plate solar collector

Rangababu et al. [27] investigated FPC to improve thermal efficiency. The author highlighted that thermal efficiency could be improved by changing the parameters of the geometry or working fluid properties. They developed a CFD model with a heat flux boundary condition on the top and assumed other sides of the collector as fully insulated. Mixed radiation model was applied on the cover glass. Outlet water temperature was validated to analytical and experimental data with an error of 30% and 20% respectively. They reported an increase in the collector efficiency by 22% by using CuO nano fluid compared to water.
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Optimization of multistage depressed collectors

Optimization of multistage depressed collectors

The geometry of the four-stage collector with the primary trajectories after optimization is shown in Fig. 11. Different aspects of fabrication and practical issues of the collector, e.g., electrode thickness and gap between the electrodes, have been taken care of while optimizing its geometry (see Fig. 3). In the present example, the efficiency of the optimized collector is nearly 91%, which is an improvement by more than 20 percentage points from the initial collector geometry. A careful look at the collector geometry in Fig. 5, which is optimized via the random walk algorithm, reveals that a few trajectories are hitting at the front face of electrode 3 and electrode 4, which could have traveled a longer path before they are collected. The energies of these electrons are not recovered fully, and this reduces the collector efficiency and may cause excessive heating. On the contrary, nearly all the primaries in Fig. 11 are collected on the backs of the electrodes. This will also help in recapturing the secondary electrons. Another comparison between the two figures shows that the length of the collector has been reduced by nearly 30%, and this has reduced both its volume and its weight. This is important for spaceborne and airborne applications.
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Experimental Investigation on the Effect of Partially Metal Foam inside the Absorber of Parabolic Trough Solar Collector

Experimental Investigation on the Effect of Partially Metal Foam inside the Absorber of Parabolic Trough Solar Collector

In the present work the efficiency of a solar parabolic trough has been investigated experimentally. Parabolic trough solar collectors constitute a proven source of thermal energy for industrial process heat and power generation. The impact of using the partially porous media in the absorber on the efficiency of PTC (parabolic trough collector) has been investigated. The porosity of copper foam is 0.9 and its pore density is 30 PPI (pores per inch). The experiments were performed for different volume flow rates from 0.5 to 1.5 L/min. and the ASHRAE 93 standard was used to test the solar collector’s performance. Results illustrate that using metal foam in the absorber has a positive impact on the collector efficiency and increases the pressure drop in the absorber. When absorber is filled with metal foam, the overall loss coefficient U L decreases 45% and it causes to increase efficiency because
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Experimental Investigation of Double Pass Solar Air Heater with Baffled Absorber Plate Vivek Singh 1, Dr. Ajay Singh2 , Ashish Verma 3

Experimental Investigation of Double Pass Solar Air Heater with Baffled Absorber Plate Vivek Singh 1, Dr. Ajay Singh2 , Ashish Verma 3

Foued Chabane et al.[2] In this paper, the heat exchanges in a Plexiglas cover solar air heater are analyzed and an explicit expression of the temperature of the air flowing in that collector is developed as a function of the space coordinate in the flow direction and the time dependent solar intensity. Then the effects of various parameters such as the inlet air temperature, the distance between the absorber and the transparent cover and the air flow on the dynamic behavior of the collector are studied. The solar air collectors were tested and their performance was compared. The efficiency depends significantly on the mass flow rate, the solar irradiation and surface geometry of the collectors. The efficiency of the collector improves with increasing solar intensity and mass flow rate both 0.012 and 0.016 kg/s, due to enhanced heat transfer to the air flow. The condition of weather affects the mass flow rate on heat transfer. The efficiency of the solar air collector is proven to be higher. The highest collector efficiency and air temperature rise were achieved by the finned collector with an angle of 45°, whereas the lowest values were obtained from the collector without fins. The efficiency of the solar air collectors depends significantly on the solar radiation and surface geometry of the collectors and the fins on the back of the absorber plate account for the mass flow rate.
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Performance Evaluation of Solar Assisted Heat Pump Water Heating System

Performance Evaluation of Solar Assisted Heat Pump Water Heating System

The main objective of this paper is to compare the performance of heat pump assisted solar water heater to conventional solar water heating system for low ambient temperature application. The theoretical analysis of solar water heater with heat pump integration is presented which shows that the collector efficiency and output water temperature can be increased compared to conventional solar water heaters under same solar intensity and ambient condition.

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Experimental Analysis on Thermal Efficiency of Evacuated Tube Solar Collector by Using Nanofluids

Experimental Analysis on Thermal Efficiency of Evacuated Tube Solar Collector by Using Nanofluids

and distilled water needed to calculate the useful heat energy, thermal energy ,collector efficiency and the convective heat transfer are measured. The dynamic viscosity (µ) is measured using brook field digital viscometer model DV – E. The thermal conductivity, specific heat and density are measured by Hot Disk Thermal Constants Analyzer (6.1), specific heat apparatus (ESD – 201) as well as the measurement of density was carried out by weighing a sample and volume. The thermal properties of nanofluids dynamic viscosity (µ) , thermal conductivity, specific heat and density are measured with different volume concentrations at 0,1%, , 3%, and 5 %vol.
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A REVIEW OF FLAT PLATE COLLECTOR AND MODIFIED FLAT PLATE COLLECTOR

A REVIEW OF FLAT PLATE COLLECTOR AND MODIFIED FLAT PLATE COLLECTOR

[7] Dong Zhang et al modified from the conventional liquid solar collector. Three working modes were presented, named (A) air heating, (B) water heating and (C) air-water compound heating. Mathematical models for air and water heating modes were developed to investigate the effect of mass flow rate on the thermal performance. An experimental set-up was established in order to test the actual performance of collector. The experimental results show that the average collector efficiency in mode A and B can achieve 51.3% and 51.4% while the mass flow rate of fluid is 0.024 kg/s and 0.13 kg/s, respectively. The maximum temperature rise of air and water reach 60.4 °C and 59.8 °C in the respective two modes. The average of total collector efficiency based on the mode C can reach 73.4%, higher than that of mode A or B. The mass flow rate is a major factor to affect the efficiency, outlet temperature of fluid and heat transfer effectiveness. When the water flow rate exceeds 0.10 kg/s, the heat removal factor increases insignificantly. To balance the efficiency and outlet temperature of fluid, the air flow rate between 0.02 kg/s and 0.025 kg/s is recommended in mode A and the water flow rate between 0.06 kg/s and 0.08 kg/s is recommended in mode B.
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Heat Transfer Optimization in Air Flat Plate Solar Collectors Integrated with Baffles

Heat Transfer Optimization in Air Flat Plate Solar Collectors Integrated with Baffles

Important of baffles in solar dryers system was also reported by Pona [25] in his research and recommended the installation of baffles raise the efficiency of the collector by 7% to 12% compared to ordinary collectors (collector without baffles). Similarly, Abene [26] assesses heat transfer in collector by inserting dif- ferent types of air obstacles disposed of in rows across the plate of collector and reported positive improvement of the performance of the drying unit. Further- more, [27] experimentally studied the impact of baffle space and baffle length in the performance of solar collector. It was found that increasing baffle length and decreasing baffle space increases the performance of solar collector. However, the reported studies have shown promising output in enhancing collector heat transfer, the optimum baffle space and length has not been reported. It can be seen that baffles reduce air space channel situated between the insulator and the absorber and increase the friction with the contact surfaces all of which increases pressure drop. Consequently, increased pressure drop increases fixed charge and fan power which leads to increased operating cost. Therefore, designing and in- stallation of baffles should be economically feasible for easy adaptation.
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Automated Optimization of Solar-Thermal Systems Using Software in a Loop

Automated Optimization of Solar-Thermal Systems Using Software in a Loop

The transfer of the determined efficiency curve parameters to Polysun ® Inside permits the calculation of the expected yield and the specific solar economic feasibility. The data transfer between the different software tools, Matlab and Polysun, was done by using XML files, that are encoded as ASCII text and, hence, are human readable. The system can be connected to an optimizer, so that the optimal configuration of construction and system parameters can be determined e.g. under the restriction of minimum solar economic feasibility. Up to 140 collector parameters including material and component costs as well as all relevant system parameters such as collector size and active storage capacity, can be set and varied. The complete simulation process is controlled by a MATLAB ® routine. First, standard values and boundary conditions must be provided in a typical simulation including
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Comparative studies on thermal efficiency of single and double glazed 
		flat plate solar water heater

Comparative studies on thermal efficiency of single and double glazed flat plate solar water heater

Farahat, F. Sarhaddi [9] determined the optimal performance and design parameters of solar flat plate collector. A detailed energy exergy analysis is carried out for evaluating the thermal performance and optical performance, exergy flows and losses as well as exergetic efficiency for a typical flat plate solar collector under given operating conditions. In this analysis ,the following geometric and operating parameters are considered as variables: the absorber plate area, dimensions of solar collector , pipe’s diameter, mass flow rate, fluid inlet and outlet temperature, the overall loss coefficient etc. and also a simulation program is developed for the thermal and exergetic calculations.
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Analysis of 2MW Solar Power Plant in Madhya Pradesh

Analysis of 2MW Solar Power Plant in Madhya Pradesh

There are different solar collector systems used for Solar Electric Power and Generation (S.E.P.G), the commonly used one is concentrator collector and Flat-plate Collector due to its low cost design, easy installation and effectiveness in cloudy day. In order to improve the efficiency of Flat-plate Collector, selective coating on the appropriate surface would be such that it absorbs maximum Solar Radiations with minimum emission of long Wave Length Radiations. Their optical, structural and electrical characteristics were studied to find out improvement in heat absorption.
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Effect of Glass Superposition on the Efficiency of the ET 200 Flat Plate Solar Collector

Effect of Glass Superposition on the Efficiency of the ET 200 Flat Plate Solar Collector

single pane of 8mm thick. In other words; the glass of 8mm thick leaves more energy, generated from the halogen lamp, to penetrate inside the collector than the composed glass (3mm+5mm), which leaves less energy reaching the absorber. As a first consequence, the incident solar flux received by water flowing in tubes attached to the absorber plate (useful flux), for the single pane of 8mm, is greater than that received in the case of the superposed panes of 3mm and 5mm (see Fig. 5).

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Development and substantiation of layout 
		of dust emissions purification systems used at mobile asphalt plants

Development and substantiation of layout of dust emissions purification systems used at mobile asphalt plants

It should be noted that, at the same time, relatively higher efficiency of fine particle separation does not always provide necessary degree of purification because swirling flows dust collectors, despite more efficient design, are still based on the principles of inertial separation. Since movable and, especially, mobile asphalt plants can work in close proximity to residential area, or in rare cases in residence territory, more severe requirements on the quality of dust emission purification, and especially on the degree of small dust fractions trapping, are imposed on purification systems included in asphalt mixing plants structure.
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