Top PDF 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.

Flat plate solar water heater is a promising technique to collect the solar energy and many factors that affect its performance. Selection of material and geometrical modulations are crucial considerations to design solar collectors. Based on our studies, to improve the thermal performance, extended surfaces internally provided to absorber tubes. According to Mr.Ganesh et al work, inverted modified fins are given higher temperature different than the standard fins with proper pitch. The primary laws of heat transfer stated that the Heat transfer increased with time as it is known, multi passes given best outlet temperature with higher efficiency. During convective heat transfer, performance increased with the fluid velocity so we have to examine the proper mass flow rate. In a finned tube collector’s friction factor and non-dimensional numbers are higher than the plain tube, especially Nusselt number, Fourier number and Prandle number is to be a main factor of higher heat transfer. From S. Saravanan et al work, absorber black painted clear toughened glass sandwich type (ABPCTC) perform better than the higher thermal conductive material like aluminium. From the Md.Imran studies, uniform velocity obtained by taper header tubes to improve thermal performance.

Unlike other sources of energy, solar energy allows independent systems to be constructed. This energy possesses a thermal conversion mode which necessitates a simple technology which is adapted to the site and to the particular region for many applications (3). A solar collector is a very special kind of heat exchanger that uses solar radiation to heat the working fluid (2). Solar air system is a type of system which collects solar energy and transforms it into heat. The general idea is that the air is flowing through solar collector and heat from sun naturally raises the temperature of the air. Flat plate solar air heaters are non-adiabatic radiative heat exchangers; they are essentially used at low temperature levels (T < 375K) in air heating and drying systems (4). Flat-plate solar air collectors have potential applications in space-heating ,air conditioning, industrial process heat, and also for heating domestic water(5). Recently many studies have been conducted on the efficiency and energy analysis of solar air

simplifications and are appropriate for the hot and moderate regions. Howeevr, the satisfactory and reliable performance of solar water heaters require proper sizing of components and accurate prediction of useful energy intake. On the other hand, the heat loss of solar collectors in the cold areas is high on the one hand, and solar radiation is low on the other hand. This brings about problems such as liquid solifidication within the collector. Therefore, optimization of system arameters is quite important for obtaining a better performance [10]. In this study, the long-term and annual performance of solar water heaters was evaluated in the city of Sanandaj, Iran. In the first phase, the parameters and general components of the system were optimized and in the second phase, the eprformance of the optimized system was evaluated.

Pakistan. Therefore, it is ideal time to explore the abundantly available renewable energy sources in Pakistan to overcome this current energy crises. Sun is one of the most attractive alternate source of energy for water heating applications (Rahman, 2010). Pakistan has huge potential of solar energy (average value 5.3 kWh/m 2 /d), which could play a vital role to mitigate the energy crises. Throughout the country, a significant amount of fossil fuel and electricity is being consumed for low to medium temperature heating applications in residential, agro-industrial, textile industry and processing plants. A cost effective renewable energy technology like solar water heaters with minimum danger and high returns is the need of residential areas (Guiney et al., 2006). To enhance the adoptability of solar water heaters in residential areas, its initial cost should be reduced with high market saturation (Kalogirou, 2004).Various types of solar thermal collectors i.e. non-concentrating collectors like vacuum tube collectors (VTC), flat plate collectors (FPC) etc. and concentrating type collectors like paraboloidal concentrators, heliostat etc.) are being used worldwide to produce low to high temperature solar thermal energy. Since, these collectors are mostly developed in advanced countries with high initial cost making it unaffordable to be purchased by developing countries. From various type of collectors, flat plate collector is simple in design and easy to develop, assemble and operate for low to medium temperature applications. The adoptability of flat plate collector on larger scale at domestic level could play a vital role for savings of huge amount of primary energy and reducing considerable amount of carbon emissions. In the light of above facts and benefits of solar thermal collectors, this research has been carried out to develop a flat plate collector using locally available material and manufacturing facilities to reduce its initial cost without compromising on its overall efficiency. The development of this low cost flat plat collector will be employed for variety of applications viz. sanitary hot water production, space heating of buildings, low temperature

In this work, the commercial CFD tool Fluent was employed to investigate the numerical simulation. A quadrilateral grid was applied to construct the computational domain using Gambit software, with a total number of 29,925 cells. For all parametric studies, Reynolds number is considered <200. An unsteady 2-D laminar incompressible model was selected to simulate the ICSSWH. At the absorber surface, a realistic and time-dependent heat flux following approximately a sinusoidal function has been introduced as user-function. It was constructed by considering global incident radiations on a tilted surface of 45° in Errachidia region (Morocco). Ambient temperatures were also generated and interpolated for three consecutive spring days. Heat losses by conduction, convection and radiation were expressed as a function of difference between ambient and absorber temperatures and an overall heat coefficient which was estimated as described by Klein [44]. The other walls (back and lateral surfaces) were supposed to be well-insulated. Moreover, a zero pressure gradient condition is used across the outlet boundary. Inlet water temperature was taken as constant in all the simulations and corresponds to 288 K.

Water heating typically represents a high percentage of energy consumption in homes and businesses, in some cases 30% or more [1]. When solar water heating systems supplement or replace conventional water heaters they displace some or all of the fuel that would have been used in those systems. While carbon intensity of baseline fuels for water heating varies, it is generally high in many locations. Consequently, emissions of greenhouse gases and other pollutants are reduced, helping to mitigate climate change while often improving local air quality, and sometimes indoor air quality as well [2]. Due to the increasing prices of the primary energy resources and their associated serious environmental issues, the use of renewable resources, especially, the solar energy is increasingly on demand in both developing and developed countries [3]. Solar energy is one of the best sources of energy for water heating. Hot water is required for domestic and industrial uses such as houses, hotels, hospitals, and mass-production and service industries [4].

The aim of the work was increase the basin water temperature economically. By utilizing the solar water heater, the basin water temperature was increased. The passive solar distillation system is a slow process for purification of saline/brackish water in solar desalination. To enhance the daily yield many options such as use of various materials for condensing covers, hybrid solar still with parabolic concentrator and evacuated tube and flat plate collector wastried by researchers. Due to low maintenance cost and simple design flat plat collector is still widely used. When flat platecollector solar water heater were integrate with solar still, extra thermal energy was supplied to the basin water from the storage tank and hence rise in water temperature was more when compared to passive solar still. Their experimental setup shown in fig. 6 included- Thermal modelling of double slope active solar still under natural circulation mode without considering the heat capacity of condensing cover and thermal insulation. Study of the flat plate solar water heater integrated with the double slope solar still.

Abstract: In this study, energetic efficiency of a solar air heater with aluminum flat plate absorber was examined experimentally for airflow velocity of 2, 3 and 4 m/s. An experimental setup was built-up and experiments were compared with the results of the analysis performed by using computational fluid dynamics (CFD) software. Results were also evaluated based on thermographic camera images.

The solar collector is considered as the heart of a solar thermal system. The main function of the solar thermal collector is to absorb solar radiation and convert it into heat to a fluid with the maximum possible efficiency [8]. The main component of the collector is absorber which generates heat by absorption of the solar radiation [9]. Also, the absorber must be designed with low emission capacity in the heat radiation spectrum and high absorption capacity in the solar spectrum [8]. The absorber contains pipes or sheets filled up with a heat transfer medium, and the medium flows to the collector to absorb the heat from solar radiation and return back to the hot water store. The heat exchanger is occasionally used to draw heat from the water-glycol mixture that is circulated in a closed circuit [9]. Moreover, there is limited heat loss to the ambient in the collector by using thermal insulation underneath the absorber and transparent cover in front [8].

The conventional energy sources are inadequate to accommodate the demand of energy which increases due to rapid industrialization and population growth. To overcome these problem non-conventional energy resources are used. Solar flat plate collector is a solar energy collector which is used to absorb solar radiation from sun and employed for heating the fluid flowing through it. Generally it uses circular pipe through which fluid is flow. Flat plate collector is use to raise the temperature of flowing fluid up to desired temperature that is up to 1000C. This collector absorbs both direct and diffuse solar radiation. Due to this reason it can works effectively on cloudy days. Hence, performance of solar flat plate collector is increased.

The application of artificial roughness in the form of rhombus shape on absorber plate is attractive roughness geometry for solar air heater due to its less complicated manufacturing process. In this paper experimental data has been collected by performing experiment to see the effect of different size of roughened elements (rhombus shape)on thermal performance of roughened flat-plate solar air heater

Experiments were conducted for flow rates of 12 lt/hr, 30 lt/hr, 54 lt/hr and 78 lt/hr with plate and tube type solar collector having absorber plate size of 40cm × 90cm and tube diameter of 10 mm. Copper tube was enhanced with six coiled wire inserts of pitch of 10 mm a nd 5 mm and wire thickness of 0.8 mm, 1.0 mm and 1.2 mm. Characteristic of Flow in tube for flow rate of 12 lt/hr was laminar flow and Characteristic of flow for flow rates of 30 lt/hr, 54 lt/hr and 78 lt/hr was turbulent.

Zhang et al. [21] investigated the performance of FPC experimentally using the results to validate a mathematical method to calculate thermal performance of FPC collectors. The geometry of the collector was 2 m in length, 1 m in width and 0.065 in thickness. The authors highlighted that the mass flow rate is a key factor that affected the performance and outlet temperature. The ambient temperature was 15.5 to 23.9 ◦ C. The inlet temperature was 21.1 to 45.1 ◦ C while the outlet temperature was in the range of 37 to 55.4 ◦ C. The average thermal efficiency was 51.4%. The authors concluded that thermal efficiency, outlet water temperature and heat transfer effectiveness were affected significantly by the flowrate. The heat removal factor did not change when the flowrate exceed 0.1 kg/s. With regards to thermal efficiency and outlet temperature, the recommended water flowrate was 0.06–0.08 kg/s.

Solar absorption cooling systems generally consist of solar collectors and storage systems in order to collect and store thermal energy, absorption chiller which required thermal energy and provides chilled water, and the cooling tower to cool the condenser in the absorption chiller. Thermal power, which can be achieved with a FPC, is the dominant driving power in solar absorption cooling systems. Thermal energy is delivered from FPC to a storage tank via a hydraulic pump. A backup heating system is normally connected to the storage tank in order to maintain the required feed temperature for the absorption chiller. The minimum driving temperature (T g ) for small capacity absorption chillers

© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 243 V Ramanathan, B Kanimozhi, V K Bhojwani(2017) had to work on how to increase the productivity of solar still. A flat mica plate is used as an absorbing plate in the conventional solar still to increase evaporation of the water from the input saline water. The flat plate absorber is placed in such a way that it is parallel to the glass cover of the solar still so as to maximize the absorption of solar radiations. By this modification, the maximum temperature of the absorber plate achieved was 95oC in comparison to 67oC of the conventional solar still and distillate output increased by 25% with a flat plate absorber compared to conventional still.

The material used for flat plate collector is copper. We took a copper sheet of dimension 3ft×2ft, which is used as an absorber plate. This dimension is taken because it is easily available in the market. The copper sheets are made to die by die maker to fix the copper tubes in it. The tubes are placed at a distance of 3 inches apart, six number of copper tubes are taken whose dimensions are ½ inch diameter. The cavities (in the form of semicircle) which are to be made on the copper sheet has taken the dimension half the circumference of copper tube. Then the two copper sheets are connected by double lap joint. The copper tube are inserted in the cavities made on copper sheet and are welded by gas welding against each other. The filler material used for gas welding was taken as bronze.

was obtained at 1.00 p.m. i.e. 33.4ºC. In general, the input temperature was found to be increasing from the morning to afternoon and then it is decreasing with little fluctuation during evening. The maximum temperature difference ΔT was 40°C at 2.00 p.m. The maximum efficiency i.e. 82.81% was achieved at ambient temp. of 31.3ºC during the time of 1.30 p.m. with solar radiation of 658W/m 2 .

The thermal performance of natural circulation solar water heating was tested on June 30, 2014 at Jimma Agricultural Mechanization Research Center using serpentine flat plate solar collector setup with batch type water tank. An estimation of solar insolation of that experimental site was made by employing engineering equation solver (EES) software. A program that compromised important parameters of air with non-dimensional units was developed. Data’s were collected on the temperature of air, sky and black body with ten minute intervals. Since once the program was developed, the collected data was inserted in the program and manipulated.

The prototype of V-trough SWH system was constructed in the Adithya institute of technology campus that is located at Coimbatore with latitude 11.1134° N and longitude of 77.0364° E. In this system, the stationary V-trough collector was designed to concentrate the sunlight onto the absorber in order to effectively convert solar energy into thermal energy. The following describe the details of each component of the prototype V-trough SWH system and how these components were constructed.