Thermal Performance Evaluation of a Solar Collector Utilizing a Novel Resistance Network Model

2020 ◽  
Author(s):  
Arman Nokhosteen ◽  
Sarvenaz Sobhansarbandi
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Thermal Behavior ◽  
Maximum Error ◽  
Solar Collectors ◽  
Resistance Network ◽  
Novel Method ◽  
Peripheral Temperature ◽  
Proper Orthogonal ◽  
Evacuated Tube

Abstract Heat pipe evacuated tube solar collectors (HPETCs) are a type of solar collectors with appealing characteristics for the application in solar water heating (SWH) technologies. In order to better understand the heat transfer phenomena in HPETCs and improve their efficiency, there is a need for a fast and robust numerical tool. Due to the complexity of the heat transfer processes involved in modeling a collector’s performance, direct numerical analysis solutions (DNS) are computationally cumbersome. Recent studies have shown that resistance network (RN) models are suitable tools for studying the performance and thermal behavior of HPETCs. In this work, a novel method of resistance network based proper orthogonal decomposition (RNPOD) is presented which can not only consider the geographical and meteorological characteristics of the ambient surroundings, but also take into account the peripheral temperature distribution of a single HPETC. Once the temperatures at each instance in time have been calculated, a POD method is used to predict the thermal behavior of the collector with desired temporal accuracy. The obtained results of this study are cross-validated with the previous experimental work of the authors, illustrating that the model is able to predict the peripheral temperature distribution with a maximum error of 10%.

An Innovative Thermal Analysis Model for Continuous Operation of a Solar Collector

2020 ◽  
Author(s):  
Arman Nokhosteen ◽  
Sarvenaz Sobhansarbandi
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Solar Irradiation ◽  
Average Error ◽  
Solar Collectors ◽  
Analysis Model ◽  
Night Time ◽  
Working Cycle ◽  
Time Operation ◽  
Boltzmann Method

Abstract Heat pipe evacuated tube solar collectors (HPETCs) are a type of solar collectors widely used in solar water heating (SWH) technologies. In order to optimize the design of SWHs, understanding the heat transfer phenomena in HPETCs is of paramount importance. The complexity of the heat transfer processes involved in modelling a collector’s performance render direct numerical simulations (DNS) computationally cumbersome. In this work, a novel hybrid numerical method is employed in order to simulate the thermal behaviour of HPETCs, both during day and night time operation. This method is comprised of a previously developed resistance network based proper orthogonal decomposition (RNPOD) method for simulation during operation hours were solar irradiation values are greater than zero; after which, an in-house code based on Lattice Boltzmann method (LBM) has been utilized for simulation when irradiance is zero. This hybrid method is able to reduce simulation time and take into account the ambient working conditions of the collector and therefore, provide an accurate assessment of the temperature distribution inside the collector during the entirety of its operation during a full working cycle. The obtained results of this study are cross-validated with the previous experimental work of the authors, illustrating that the model is able to predict the peripheral temperature distribution with an average error of less than 10%.

Review of Thermal Performance and Efficiency in Evacuated Tube Solar Collector with Various Nanofluids

2017 ◽  
Vol 25 (02) ◽  
pp. 1730001 ◽  
Author(s):  
Hyeongmin Kim ◽  
Jinhyun Kim ◽  
Honghyun Cho
Keyword(s):  
Heat Transfer ◽  
New Technology ◽  
Heating System ◽  
Experimental Methods ◽  
Solar Collectors ◽  
Parabolic Trough ◽  
Solar Absorption ◽  
Evacuated Tube Solar Collector ◽  
Evacuated Tube ◽  
Technology Area

With the development of nanotechnology, building a new technology area in a variety of fields and achieving the best performance has become possible. Several studies on the performance of a solar heating system have been conducted using various nanofluids because the efficiency of heat transfer of nanofluids is high. Various previous studies, including theoretical, numerical, and experimental methods, were conducted using nanofluids for flat-plate, evacuated tube, direct solar absorption, parabolic trough, and heat pipe solar collectors. The present work provides an overview of the recent research on the performance of evacuated tube solar collectors using various nanofluids. The experimental and numerical results reported by several researchers, such as the thermal conductivity, heat capacity, and heat transfer coefficient of nanofluids, are first reported. The studies on the evacuated tube solar collectors with nanofluids were then investigated and summarized.

A Study on Heat Transfer Model in Wood Particle during the Pyrolysis

2011 ◽  
Vol 704-705 ◽  
pp. 462-467
Author(s):  
Liang Jing Jing ◽  
Rui Li ◽  
Yu Yu Li
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Thermal Behavior ◽  
Thermophysical Properties ◽  
Fast Pyrolysis ◽  
Wood Particle ◽  
Heat Transfer Model ◽  
Transient Temperature ◽  
Transfer Model ◽  
Optimization Of Parameters

Heat transfer in wood particle controls the process of the pyrolysis. This paper makes a 2-D transient heat transfer model in cylindrical to predict the thermal behavior of wood particle in the process of fast pyrolysis. Wood anisotropy and thermophysical properties are considered in this model, as well as the influence of heat reaction on temperature distribution in wood particle. Based on the calculation of transient temperature in wood particle, and analysis of the temperature distribution during the process of wood fast pyrolysis at different time, this paper preliminarily discusses the optimization of parameters in wood particle fast pyrolysis. Keywords: pyrolysis, heat transfer, particle, wood

scholarly journals Assessment of the annual performance of solar collectors by means of the utilizability method

2020 ◽  
Vol 207 ◽  
pp. 02007
Author(s):  
Merima Zlateva
Keyword(s):  
Heat Transfer ◽  
Critical Value ◽  
Climatic Conditions ◽  
Operating Conditions ◽  
Heat Transfer Fluid ◽  
Solar Collectors ◽  
Different Temperatures ◽  
Evacuated Tube ◽  
Inclined Surface

This report presents some results from a comparative analysis of the long-term efficiency of flat-plate and evacuated tube solar collectors under different operating conditions. The analysis involves calculation of the daily utilizibility factor, which is defined as the fraction of total monthly solar radiation over an inclined surface that exceeds the critical value. The monthly values of the critical radiation and the daily utilizability factor for the solar collectors are determined under different climatic conditions and different temperatures of the heat transfer fluid. The obtained results are used to compare the annual performance of the solar collectors.

Numerical Simulation of Solidification Process for a Machine Tool Bed

2011 ◽  
Vol 675-677 ◽  
pp. 987-990
Author(s):  
Ling Tang ◽  
Xu Dong Wang ◽  
Hai Jing Zhao ◽  
Man Yao
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Machine Tool ◽  
Computation Time ◽  
Solidification Process ◽  
Field Calculation ◽  
Original Design ◽  
Calculation Results ◽  
Improved Design

In this paper, the flow, heat transfer and stress during solidification process of the machine tool bed weighed about 2.5ton that has been optimized by structural topologymethod, was calculated with ProCAST software, and the causes of the crack forming in the casting of the machine tool bed was analysed. According to the calculation results, the structural design of the local part where cracks tends to form has been improved, and the heat transfer and the stress are calculated again. By comparing the temperature field with filling of molten cast iron and without filling, it has been found that there was little effect of filling on the results of temperature distribution of the cast, therefore the effect of filling can be ignored in the following temperature field calculation to save computation time. The model has been simplified in the stress field calculation with considering the complexity of the machine tool bed and the cost of computation. Then, the merits and demerits of the original design and the improved design are compared and analyzed depending on the calculated temperature and stress results. It is suggested that the improved one could get a more uniform temperature distribution and then the trend of the crack occurring can be greatly reduced. These results could provide a guide for the actual casting production, achieving the scientific control of the production of castings, ensuring the quality of the castings.

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