The Effect of a Thermotropic Material on the Optical Efficiency and Stagnation Temperature of a Polymer Flat Plate Solar Collector

2014 ◽  
Author(s):  
Adam C. Gladen ◽  
Jane H. Davidson ◽  
Susan C. Mantell
Keyword(s):  
Flat Plate ◽  
Hot Water ◽  
Normal Operation ◽  
Stagnation Temperature ◽  
Service Temperature ◽  
Thermal Systems ◽  
Optical Efficiency ◽  
Maximum Service Temperature ◽  
Flat Plate Solar Collector ◽  
Flat Plate Collector

Solar hot water and space heating systems constructed of commodity polymers have the potential to significantly reduce the initial cost of solar thermal systems. However, a polymer absorber must be prevented from exceeding its maximum service temperature during stagnation. Here we consider the addition of a thermotropic material to the surface of the absorber. The thermotropic layer provides passive overheat protection by switching from high transmittance during normal operation to high reflectance if the temperature of the absorber becomes too high. In this paper, a one dimensional model of a glazed, flat-plate collector with a polymer absorber and thermotropic material is used to determine the effects of the optical properties of a thermotropic material on optical efficiency and stagnation temperature of the collector. A key result is identification of the reflectance in the translucent state required to provide overheat protection for potential polymer absorber materials. For example, the reflectance of a thermotropic material in the translucent state should be greater than or equal to 51% for a polypropylene absorber which has a maximum service temperature of 115 °C.

The Effect of a Thermotropic Material on the Optical Efficiency and Stagnation Temperature of a Polymer Flat Plate Solar Collector

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Adam C. Gladen ◽  
Jane H. Davidson ◽  
Susan C. Mantell
Keyword(s):  
Flat Plate ◽  
Hot Water ◽  
Normal Operation ◽  
Stagnation Temperature ◽  
Service Temperature ◽  
Thermal Systems ◽  
Optical Efficiency ◽  
Maximum Service Temperature ◽  
Flat Plate Solar Collector ◽  
Flat Plate Collector

Solar hot water and space heating systems constructed of commodity polymers have the potential to reduce the initial cost of solar thermal systems. However, a polymer absorber must be prevented from exceeding its maximum service temperature during stagnation. Here, the addition of a thermotropic material to the surface of the absorber is considered. The thermotropic layer provides passive overheat protection by switching from high transmittance during normal operation to high reflectance if the temperature of the absorber becomes too high. A one dimensional model of a glazed, flat-plate collector with a polymer absorber and thermotropic material is used to determine the effects of the optical properties of the thermotropic material on the optical efficiency and the stagnation temperature of a collector. A key result is identification of the reflectance in the translucent state required to provide overheat protection for potential polymer absorber materials. For example, a thermotropic material in its translucent state should have a solar-weighted reflectance greater than or equal to 52% to protect a polypropylene absorber which has a maximum service temperature of 115 °C.

scholarly journals Aplicaciones del Captador Solar de Placa Plana y del Captador de Tubo de Vacío en la Edificación = Applications of the Flat Plate Solar Collectors and the Vacuum Tube Solar Collectors in Building

2018 ◽  
Vol 4 (3) ◽  
pp. 25 ◽  
Author(s):  
Daniel Ferrández ◽  
Carlos Moron ◽  
Jorge Pablo Díaz ◽  
Pablo Saiz
Keyword(s):  
Flat Plate ◽  
Solar Collector ◽  
Energy Demand ◽  
Hot Water ◽  
Solar Thermal ◽  
Solar Collectors ◽  
Thermal Systems ◽  
Vacuum Tube ◽  
Solar Thermal Collectors ◽  
Flat Plate Solar Collector

ResumenEl actual Código Técnico de la Edificación (CTE) pone de manifiesto la necesidad de cubrir parte de la demanda energética requerida para el abastecimiento de agua caliente sanitaria y climatización de piscinas cubiertas mediante sistemas de aprovechamiento de la energía solar térmica. En este artículo se presenta una comparativa entre las dos principales tipologías de captadores solares térmicos que existen en el mercado: el captador de placa plana y el captador de tubo de vacío, atendiendo a criterios de fracción solar, diseño e integración arquitectónica. Todo ello a fin de discernir en qué circunstancias es más favorable el uso de uno u otro sistema, comparando los resultados obtenidos mediante programas de simulación con la toma de medidas in situ.AbstractThe current Technical Building Code (CTE) highlights the need to cover part of the energy demand required for the supply of hot water and heating of indoor swimming pools using solar thermal systems. This article presents a comparison between the two main types of solar thermal collectors that exist in the market: the flat plate solar collector and the vacuum tube solar collector, according to criteria of solar fraction, design and architectural integration. All of this in order to discern in what circumstances the use of one or the other system is more favourable, comparing the results obtained through simulation programs with the taking of measurements in situ.

Design, Implementation, and Evaluation of Thermal Performance of a Thermosiphon Flat-Plate Solar Collector for Water Heating in Ecuadorian Coastal Region

2017 ◽  
Author(s):  
Carola Sánchez ◽  
José Macías ◽  
Jonathan León ◽  
Geancarlos Zamora ◽  
Guillermo Soriano
Keyword(s):  
Flat Plate ◽  
Thermal Performance ◽  
Solar Collector ◽  
Storage Tank ◽  
Hot Water ◽  
Attractive Alternative ◽  
Local Market ◽  
Water Heating ◽  
Water Storage Tank ◽  
Flat Plate Solar Collector

Passive solar water heating (SWH) is a convenient method to meet domestic hot water requirements in rural areas, where electricity may not be available or fuel supply might be limited due to difficult access. In this work, a low-cost thermosiphon flat-plate solar collector alternative is presented. The design was purposely limited to materials and recyclable products widely available in the local market, such as Tetra Pak, plastic bottles, and polypropylene (PP) fittings and pipes. Since PP is a thermoplastic polymer, a poor heat conductor, it was necessary to ensure a suitable system isolation to obtain an optimum thermal performance, comparable to commercial solar collectors. The design was built and tested in Guayaquil, Ecuadorian coastal city. Six inexpensive temperature sensors were placed at the entrance and exit of the collector, on the flat-plate and inside the hot water storage tank. Data was recorded using an Arduino single-board computer and later analyzed with the data gathered via weather station. The implementation costs of the system are approximately US$300, the overall performance during January 2017 fluctuated between 54% and 23%, and the storage tank temperature range varied from to 46°C to 33°C. Due to its reliability and affordable cost, the SWH system is an attractive alternative to an Ecuadorian commercial solar flat plate collector, which price is set between US$600 and US$700, it has an efficiency around 60%, and the average annual storage tank temperature is 62°C.

Generalized Analytical Equation for the Top Heat Loss Factor of a Flat-Plate Solar Collector With N Glass Covers

1994 ◽  
Vol 116 (1) ◽  
pp. 43-46 ◽  
Author(s):  
S. K. Samdarshi ◽  
S. C. Mullick
Keyword(s):  
Flat Plate ◽  
Heat Loss ◽  
Loss Factor ◽  
Analytical Equation ◽  
Empirical Equations ◽  
Additional Advantage ◽  
Computational Errors ◽  
Flat Plate Solar Collector ◽  
Flat Plate Collector ◽  
Semi Empirical

A generalized analytical equation for the top heat loss factor of a flat-plate collector with one or more glass covers has been developed. The maximum computational errors resulting from the use of the analytical equation with several simplifications are ± 5 percent compared to numerical solution of the set of heat balance equations. The analytical equation is considerably more accurate than the available semi-empirical equations over the entire range of variables covered. An additional advantage of the proposed technique over the semi-empirical equations is that results can be obtained for different values of sky temperature, using any given correlation for convective heat transfer in the air gap spacings, and for any given values of fluid (air in the present case) properties.

scholarly journals Investigation of Performance of Solar Flat and Curved Plate Collectors through Numerical Simulations

2021 ◽  
Vol 40 (1) ◽  
pp. 66-74
Author(s):  
Luqman Ahmed Pirzada ◽  
Xiaoli Wu . ◽  
Qaiser Ali ◽  
Asif Khateeb .
Keyword(s):  
Solar Energy ◽  
Flat Plate ◽  
Solar Collector ◽  
Numerical Study ◽  
Hot Water ◽  
Working Fluid ◽  
Solar Panels ◽  
Modeling Tools ◽  
Design Work ◽  
Flat Plate Collector

Solar energy is radiant light as a form of thermal heat energy which can be obtained and used by means of a variety of solar apparatus. As apparatus the flat and curved plate solar collector is specifically designed for assembling solar energy as a solar water heater system. The designing potency of this collector lone can generate medium level hot water from radiant sunlight source via absorbed plates. Standard type flat and curved plates solar collector plates are mostly used in remote coldest regions of the world where hot water is consumed for commercial and domestic purposes. These types of solar collector Plates can cheaply be manufactured compared to other solar panels like solar Shingles, Polycrystalline Solar Panels, Mono-crystalline Solar Panels, and Thin Film Solar Panels. For future work, this proposed pre-design is recommended for fabrication. A numerical study was carried-out on eight city locations in China by tracing their horizontal and vertical longitudinal, latitudinal lines noting the date, time and sunlight feeding of temperatures in the Celsius scale with the help of simulation and modeling tools like CFD, ANSYS FLUENT software, mesh geometry tools, and by using the Navier-Stokes and Continuity equations by fluid flow discharge rate, mass flow, water temperature and dropping of temperature, radiation working mechanisms, dimensions of water flowing tubes and absorber plates, density, the velocity of water as the working fluid, the viscosity of water in a cold and hot state as a process of Pre-design. Work also focuses on the comparison between flat plate collector and curved plate collector radiant sunlight absorption, As end result it is found the Curved plate collector produces 22% more elevated heat of outgoing water than flat plate collector.

scholarly journals Hybrid system solar collectors - heat pumps for domestic water heating

2019 ◽  
Vol 23 (6 Part A) ◽  
pp. 3675-3685
Author(s):  
Simon Marcic ◽  
Rebeka Kovacic-Lukman ◽  
Peter Virtic
Keyword(s):  
Solar Radiation ◽  
Flat Plate ◽  
Heat Pump ◽  
Autonomous System ◽  
Identical Condition ◽  
Heat Pumps ◽  
Hot Water ◽  
Water Heating ◽  
Domestic Water ◽  
Flat Plate Collector

This paper deals with the use of solar energy, heat pumps, and solar system-heat pump combinations for domestic water heating. The testing of solar tiles, flat plate collectors as an autonomous system, as well as flat plate collector-heat pump and solar tile-heat pump combinations, are presented. Black-coloured water absorbs solar radiation flows through solar tiles made of transparent polymethyl methacrylate (CH2C(CH3)COOCH3). At the same time, solar tiles are used as a roof covering and as a solar radiation collector. Hot water from solar tiles or a flat plate collector is directed to the heat pump, which increases the temperature of water entering the boiler heating coil. The heat of water heated in solar tiles or in flat plate collectors serves as a source of energy for the heat pump. Since the goal was realistically evaluate the efficiency of solar tiles in comparison with the flat plate collector, extensive measurements of both systems under identical condition were carried out. The experiments were carried out in rainy, cloudy, and clear weather.

Experimental Analysis of a Flat Plate Solar Collector System for Small-Scale Desalination Applications

2014 ◽  
Vol 984-985 ◽  
pp. 800-806
Author(s):  
G. Jims John Wessley ◽  
P. Koshy Mathews
Keyword(s):  
Solar Radiation ◽  
Flat Plate ◽  
Heating System ◽  
Maximum Temperature ◽  
Small Scale ◽  
Collector System ◽  
Typical Day ◽  
Flat Plate Solar Collector ◽  
Solar Water Heating System ◽  
Flat Plate Collector

This paper presents the results of the experimental investigation on a solar flat plate collector carried out at Coimbatore, India (11°N Latitude and 74°E Longitude). The collector tubes allowed the water to flow twice across the flat plate collector using a circulating pump during which the water gets heated by the solar radiation received by the absorber. The maximum temperature of water obtained on a typical day in the month of April was 64°C with a solar radiation of 932.2651 W/m2. The available solar radiation strongly influences the temperature gain of the system while the wind velocity plays a considerable role in influencing the heat lost by the system. It is observed that the two-pass flow of water across the absorber plate results in a maximum temperature gain with an overall collector efficiency of 43.7 %. This solar water heating system using flat plate collector can be used for small-scale desalination applications.

Heat Loss Characteristics of a Roof Integrated Solar Micro-Concentrating Collector

2011 ◽  
Author(s):  
Tanzeen Sultana ◽  
Graham L. Morrison ◽  
Siddarth Bhardwaj ◽  
Gary Rosengarten
Keyword(s):  
Heat Transfer ◽  
Heat Loss ◽  
Large Scale ◽  
Radiation Heat Transfer ◽  
Industrial Process ◽  
Hot Water ◽  
Solar Thermal ◽  
Convection Heat ◽  
Thermal Systems ◽  
Optical Efficiency

Concentrating solar thermal systems offer a promising method for large scale solar energy collection. It is feasible to use concentrating solar thermal systems for rooftop applications such as domestic hot water, industrial process heat and solar air conditioning for commercial, industrial and institutional buildings. This paper describes the thermal performance of a new low-cost solar thermal micro-concentrating collector (MCT), which uses linear Fresnel reflector technology and is designed to operate at temperatures up to 220°C. The modules of this collector system are approximately 3 meters long by 1 meter wide and 0.3 meters high. The objective of the study is to optimize the design to maximise the overall thermal efficiency. The absorber is contained in a sealed enclosure to minimise convective losses. The main heat losses are due to natural convection inside the enclosure and radiation heat transfer from the absorber tube. In this paper we present the results of a computational investigation of radiation and convection heat transfer in order to understand the heat loss mechanisms. A computational model for the prototype collector has been developed using ANSYS-CFX, a commercial computational fluid dynamics software package. Radiation and convection heat loss has been investigated as a function of absorber temperature. Preliminary ray trace simulation has been performed using SolTRACE and optical efficiency has been evaluated. Finally, the MCT collector efficiency is also evaluated.

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