Mathematical model development and optimal design of the horizontal all-glass evacuated tube solar collectors integrated with bottom mirror reflectors for solar energy harvesting

Mao, Chongyang; Li, Muran; Li, Na; Shan, Ming; Yang, Xudong

doi:10.1016/j.apenergy.2019.01.006

Cited by 42 publications

(4 citation statements)

References 32 publications

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“…[109] ETC is applied to residential and industrial applications for water heating, solar drying, desalination, and air conditioning. It is suitable for cloudy days [110] and temperatures above 80 °C. The evacuated tube collector has a lower heat loss coefficient, reducing heat loss from the collector to the air, especially in high-temperature applications.…”

Section: Stationary Solar Collectormentioning

confidence: 99%

Review on the Progress of Solar Water Heaters and Their Future Perspectives

2023

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A solar water heater (SWH) converts solar radiation into thermal energy for various purposes, and its technology has experienced numerous developments. Many studies have focused on developing, optimizing, and analyzing the technological configurations of SWH to improve its thermal efficiency, but they rarely achieve 80% efficiency. This review aims to provide a broad overview of SWH, including the energetic and exergetic approaches and analyses, technological development, and examines advantages, disadvantages, and further developments. Various collectors of the SWH and related studies are also highlighted, and the results identify the technical and policy challenges of the implementation. Suggested potential solutions to these challenges are presented with further directions. Furthermore, this study also discusses the limitations of the current SWH technology by presenting the specifications and characteristics. It also presents the mathematical equation model often used, the technology potential, and the results of the latest studies and developments regarding SWH technology. The prospects for further development of the most promising SWH should be analyzed.

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Section: Stationary Solar Collectormentioning

confidence: 99%

Review on the Progress of Solar Water Heaters and Their Future Perspectives

2023

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“…Reference [22] presents several physically-based mathematical models describing the dynamic behaviour of unglazed flat plate collectors. In [23] the possibility of a device that can be used for heating and domestic hot water production was developed, in which the collector is equipped with a mirror. In connection with this, a physically-based model was worked out for evacuated tube solar collectors, which can be used to estimate the total solar radiation reaching the collector.…”

Section: Introductionmentioning

confidence: 99%

New Physically-Based Mathematical Model and Experiments for a Recently Invented Solar Pot

Rátkai,

Géczi,

Kicsiny

et al. 2024

Preprint

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The studied solar pot is a recent invention, which gained a utility model protection in 2021 from the Hungarian Intellectual Property Office under patent number 5489. The device is made for environmentally friendly cooking or heating (by utilizing solar energy) of foods and liquids. Its structure is similar to a double pipe heat exchanger, it has an outer mantle and an inner cooking tank. The goals of the paper are proposing a new physically-based mathematical model describing the solar pot and carrying out computer experiments with it, assembling an experimental system of the pot connected with a solar collector and performing measurements on it. Based on the results, the solar pot can successfully be used for cooking or sterilizing foods or liquids during the studied time period, in Hungary.

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“…12 Mao et al (2019) used the method suggested by Shah and Furbo to investigate the optical performance of horizontal ETCs equipped with a reflector behind as a booster of radiation collection for space heating of buildings in winters. 13 Indeed, the method by dividing tubular receiver into a number of FPC-like finite element (FPC-like finite method, in short) can simplify the calculation of diffuse radiation as sky diffuse radiation on each finite FPC can be simply estimated based on the view factor from the finite PFC (tilted at β from the horizon) to the sky, which is equal to 0.5 (1cosβ). However, the most concern on such FPC-like finite method arises that the view factor from a finite PFC to the sky is not equal to 0.5 (1cosβ) due to shading between adjacent tubes, furthermore such shading effect differs for different finite PFC, and the actual view factor of each finite PFC to the sky dome should be determined based on the definition of radiative shape factor first then integrating over the sky dome viewed by the finite FPC, therefore, the calculation of actual view factor for each finite FPC is extremely complex, making the estimate difficult and time-consuming.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, effects of relevant solar incident angles and shading between adjacent tubes were considered 12 . Mao et al (2019) used the method suggested by Shah and Furbo to investigate the optical performance of horizontal ETCs equipped with a reflector behind as a booster of radiation collection for space heating of buildings in winters 13 . Indeed, the method by dividing tubular receiver into a number of FPC‐like finite element (FPC‐like finite method, in short) can simplify the calculation of diffuse radiation as sky diffuse radiation on each finite FPC can be simply estimated based on the view factor from the finite PFC (tilted at β from the horizon) to the sky, which is equal to 0.5 (1 – cos β ).…”

Section: Introductionmentioning

confidence: 99%

A note on estimation of diffuse radiation collected by all‐glass evacuated solar tube collectors

Zhang

Tang

2021

Intl J of Energy Research

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To simplify the estimation of diffuse radiation from the sky and ground collected by all-glass evacuated solar tube collectors (ETCs), four methods were proposed and used in the past. Among them, the one by assuming the directional intensity of diffuse radiation projected on the plane coplanar with crosssection of solar tubes (2-D model) to be isotropic is simpler as mathematical expressions for the estimate of diffuse collectible radiation can be directly derived in this case. However, such assumption is not true for tilted evacuated solar tubes (ET), and the three-dimensional isotropic diffuse radiation (3-D model) should be used. In this note, a trail is made to estimate diffuse radiation collected by tilted-arranged ET collectors (T-type ETC) based on 3-D model and compare with those obtained based on the 2-D model. Results show that the diffuse radiation collected by T-type ETCs estimated based on 2-D and 3-D models are highly in agreement, and the difference between two estimates is dependent on the tilt-angle (β) of ETCs. For the case of β = 0 and 90 , the both estimates are completely identical as expected. For T-type ETCs with ETs sizing 47/58 mm in diameter of inner/outer tubes and spacing (B) between centers of two adjacent ETs less than 80 mm, the relative deviation between two estimates for diffuse radiation from the sky is less than 0.65% and that for diffuse radiation reflecting from the ground is less than 1.7% when β > 20 . This means that the 2-D model is reasonable and advisable for a quick estimation of collectible diffuse radiation of ETCs. K E Y W O R D S2-D diffuse radiation model, 3-D diffuse radiation model, comparison of estimates, estimation of collectible diffuse radiation, evacuated tube solar collector

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Mathematical model development and optimal design of the horizontal all-glass evacuated tube solar collectors integrated with bottom mirror reflectors for solar energy harvesting

Cited by 42 publications

References 32 publications

Review on the Progress of Solar Water Heaters and Their Future Perspectives

Review on the Progress of Solar Water Heaters and Their Future Perspectives

New Physically-Based Mathematical Model and Experiments for a Recently Invented Solar Pot

A note on estimation of diffuse radiation collected by all‐glass evacuated solar tube collectors

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