Experimental evaluation of thermophysical properties of oil‐based titania nanofluids for medium temperature solar collectors

2020 ◽  
Vol 51 (6) ◽  
pp. 792-802
Author(s):  
J. Akhter ◽  
S.I. Gilani ◽  
H.H. Al‐Kayiem ◽  
M. Ali ◽  
F. Masood
Keyword(s):  
Thermophysical Properties ◽  
Experimental Evaluation ◽  
Solar Collectors ◽  
Medium Temperature

scholarly journals CONSTRUCCIÓN DE UNA VIVIENDA SOLAR EN BASE A LAS PROPIEDADES TERMOFISICAS Y EVALUACIÓN EXPERIMENTAL DE SU CONFORT TÉRMICO EN ILAVE

2014 ◽  
Vol 16 (01) ◽  
Author(s):  
ARTURO FLORES CONDORI
Keyword(s):  
Relative Humidity ◽  
Solar Energy ◽  
Thermal Comfort ◽  
Thermophysical Properties ◽  
Experimental Evaluation ◽  
Meteorological Data ◽  
Thermal Inertia ◽  
Living Condition ◽  
Simulation Software ◽  
Experimental Structure

<h4 class="text-primary">Resumen</h4><p style="text-align: justify;">El presente artículo consistió en la construcción de una vivienda solar pasivo a base de propiedades termofísicas (Conductividad térmica, calor específico, difusividad térmica y inercia térmica) y desarrollar una evaluación experimental del rendimiento térmico aportado por los elementos constructivos, en una comunidad rural Colloco - Ilave, provisto de adecuado aislamiento térmico en la envolvente (doble pared de adobe, en el cielo raso: paja­carrizo-yeso y en el piso: tierra apisonada-cama de piedra-plástico-paja y totora), ubicación, la orientación y un sistema de acumulación de energía adecuadamente diseñada a base a encapsulado de piedras andesitas porosas y de totora. La distribución de energía calorífica almacenada fue primordial al ambiente dormitorio que esto permite el aprovechamiento de la energía solar para lograr que la temperatura al interior de la vivienda sea más confortable. Se realizó el análisis del comportamiento térmico de la vivienda construida y la vivienda rural típica, para lo cual se tomaron los datos meteorológicos de la zona (temperatura, humedad relativa, velocidad del viento y radiación solar), también se registraron la temperatura y humedad relativa del aire en el ambiente interior y exterior de las viviendas desde 19 de junio al 02 de julio del 2013. Obteniéndose en la vivienda construida las temperaturas máximas y mínimas de 15.85ºC y 11.88ºC respectivamente. Según la evaluación de la vivienda construida se aprecia un incremento de temperatura mínimo de 6.26°C, respecto a la vivienda típica. Para validar estos resultados experimentales, se ha utilizado el programa de simulación térmica EnergyPlus para los datos meteorológicos de la zona (3 868 msnm), comprobándose por el método correlativo, el factor de correlación fue r=0.92575. Este incremento de la temperatura en el interior de la vivienda construida contribuye alcanzar un confort térmico, permitiendo una condición de vida saludable para el poblador rural.</p><p><strong>PALABRAS CLAVE: </strong>* confort térmico * energía solar * propiedades termofísica * simulación térmica</p><h4 class="text-primary">ABSTRACT</h4><p><strong>CONSTRUCTION OF A SOLAR DWELLING BASED ON THERMOPHYSICAL PROPERTIES AND EXPERIMENTAL EVALUATION OF THERMAL COMFORT - ILAVE, PUNO - PERU»</strong></p><p style="text-align: justify;">The present article consists in the construction of a passive solar house based on the study of thermophysical properties (thermal conductivity, specific heat, thermal diffusivity and thermal inertia). We developed an experimental evaluation of the thermal efficiency contributed by different constructive materials, In the rural community of Colloco - Ilave. Once adequate thermal insulation was provided in the enveloping surface (double wall construction of sun-dried adobe brick, a false ceiling with: straw, bamboo and plaster. In the floor: tamped soil, stone bed, plastic, straw and totora reed). Location and position of the solar home in coordination with an energy accumulation system adequately designed with an encapsulation of porous Andesitic stones and Totora reed. Distribution of the stored thermal energy was directed primarily to the main bedroom, this enabled adequate use of solar energy in order to achieve a comfortable temperature within the dwelling. We analyzed the thermal behavior of both this experimental structure and that of a common rural dwelling; taking the interior and exterior meteorological readings found in the two dwelling types. (temperature, relative humidity, wind velocity and solar radiation). Between June 19th and July 2nd, the temperature and relative humidity of the interior of the experimental structure measured a max. of 15.85ºC (60.53ºF) and 11.88ºC (53.384ºF) respectively. According to a general evaluation of the experimental structure, there was a temperature increment of 6.26°C (=¿?ºF) compared to the average temperature of a normal dwelling. In order to confirm these experimental results we used the thermic simulation software EnergyPlus, entering the meteorological data of the area (3,868 meters above sea level=12690.3 ft.) using the correlative method and a correlative factor of r=0.92575. This higher temperature inside of the experimental structure contributes to attaining a thermic comfort allowing for a healthy living condition for the rural inhabitant.</p><p><strong>KEY WORDS: </strong>* thermal comfort * solar energy * thermophysical properties * thermal simulation</p>

scholarly journals Ray Tracing Study of Optical Characteristics of the Solar Image in the Receiver for a Thermal Solar Parabolic Dish Collector

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Saša R. Pavlovic ◽  
Velimir P. Stefanovic
Keyword(s):  
Ray Tracing ◽  
Low Cost ◽  
Optical Design ◽  
Solar Concentrator ◽  
Solar Collectors ◽  
Focal Distance ◽  
Medium Temperature ◽  
Parabolic Dish ◽  
Parabolic Dish Concentrator ◽  
Temperature Levels

This study presents the geometric aspects of the focal image for a solar parabolic concentrator (SPC) using the ray tracing technique to establish parameters that allow the designation of the most suitable geometry for coupling the SPC to absorber-receiver. The efficient conversion of solar radiation into heat at these temperature levels requires a use of concentrating solar collectors. In this paper detailed optical design of the solar parabolic dish concentrator is presented. The system has diameter D=3800 mm and focal distance f=2260 mm. The parabolic dish of the solar system consists of 11 curvilinear trapezoidal reflective petals. For the construction of the solar collectors, mild steel-sheet and square pipe were used as the shell support for the reflecting surfaces. This paper presents optical simulations of the parabolic solar concentrator unit using the ray tracing software TracePro. The total flux on the receiver and the distribution of irradiance for absorbing flux on center and periphery receiver are given. The goal of this paper is to present the optical design of a low-tech solar concentrator that can be used as a potentially low cost tool for laboratory scale research on the medium-temperature thermal processes, cooling, industrial processes, polygeneration systems, and so forth.

scholarly journals Towards a Standard Testing Methodology for Medium-temperature Solar Collectors with Variable Geometry

2014 ◽  
Vol 57 ◽  
pp. 2904-2913 ◽  
Author(s):  
Fabienne Sallaberry ◽  
Ramon Pujol-Nadal ◽  
Alberto Garcia de Jalón ◽  
Víctor Martínez-Moll
Keyword(s):  
Variable Geometry ◽  
Solar Collectors ◽  
Medium Temperature ◽  
Testing Methodology ◽  
Standard Testing

scholarly journals Thermal Characterization of Medium-Temperature Phase Change Materials (PCMs) for Thermal Energy Storage Using the T-History Method

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7371
Author(s):  
Paulina Rolka ◽  
Roman Kwidzinski ◽  
Tomasz Przybylinski ◽  
Adam Tomaszewski
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Thermophysical Properties ◽  
Phase Change Materials ◽  
Experimental Tests ◽  
Stored Energy ◽  
Medium Temperature ◽  
Heating Systems ◽  
Selection Of

To reduce energy consumption and increase energy efficiency in the building sector, thermal energy storage with phase change materials (PCMs) is used. The knowledge of the thermophysical properties and the characteristics of PCMs (like their enthalpy changes and the distribution of stored energy over a specified temperature range) is essential for proper selection of the PCM and optimal design of the latent thermal energy store (LHTES). This paper presents experimental tests of the thermophysical properties of three medium-temperature PCMs: OM65, OM55, RT55, which can be used in domestic hot water installations and heating systems. Self-made test chambers with temperature control using Peltier cells were used to perform measurements according to the T-history method. In this way the temperature range of the phase transition, latent heat, specific heat capacity, enthalpy and the distributions of stored energy of the three PCMs were determined. The paper also presents measurements of the thermal conductivity of these PCMs in liquid and solid state using a self-made pipe Poensgen apparatus. The presented experimental tests results are in good agreement with the manufacturers’ data and the results of other researchers obtained with the use of specialized instruments. The presented research results are intended to help designers in the selection of the right PCM for the future LHTES co-working with renewable energy systems, waste heat recovery systems and building heating systems.

Thermal performance of a low and medium temperature flat plate solar collector when controlling the output-input temperature difference and the tilt angle

2021 ◽  
pp. 1-17
Author(s):  
García-Rincón Marco Antonio ◽  
Flores-Prieto José Jassón ◽  
Montoya-Márquez Orlando
Keyword(s):  
Flat Plate ◽  
Temperature Difference ◽  
Vertical Position ◽  
Solar Collectors ◽  
Medium Temperature ◽  
Joule Effect ◽  
Heat Flow Calorimetry ◽  
Flat Plate Solar Collector ◽  
Overall Heat Loss Coefficient ◽  
Indoor Conditions

Abstract This work presents a sensitivity analysis of the overall heat loss coefficient UL and the thermal efficiency η in low and medium temperature encapsulated flat plate solar collectors when controlling the output-input temperature difference ΔT and the angle of inclination β. The UL and η were determined using heat flow calorimetry at indoor conditions, emulating the solar radiation by the Joule effect and a PID control. The angle of inclination β range was 0-90°, and the ΔT range was 5.0-25.0 K. The ambient temperature and the mass flow rate were preset for each test. The UL experimental uncertainty was ±0.85 W/m2K for the inclination range of 0-45° and ±0.27 W/m2K for the inclination range of 45-90°. The results matched previous outcomes with a difference of up to 0.3 W/m2K. The UL behaved exponentially as β increased from horizontal to vertical position and linearly with ΔT. It was also observed that the UL and the efficiency were sensitive to the confined airflow variations. This model shows a sensitivity of low and medium temperature flat plate solar collectors, as the efficiency increased 140% when β was raised and 40% with ΔT.

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