Experimental and simulation on night heat dissipation characteristics and freezing process of evacuated tube solar water heaters

Li, Tao; Wang, Zhifan; Yu, Junyong; Mao, Qianjun

doi:10.1016/j.ijthermalsci.2023.108455

Cited by 5 publications

(1 citation statement)

References 36 publications

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“…Under freezing conditions, its thermal conductivity is 0.56 W/(m•K), density is 917 kg/m 3 , and specific heat is 2090 J/(kg•K). The specific physical parameters are shown in Table 2 [41,42]. In the boundary conditions, the ambient temperature is given as a temperature boundary condition that varies with time by using a user-defined function (UDF) in ANSYS Fluent.…”

Section: Boundary Condition Settingsmentioning

confidence: 99%

The Influence of Storage Tank Volume on the Nighttime Heat Dissipation and Freezing Process of All-Glass Vacuum Tube Solar Water Heaters

Wang

Mao

et al. 2023

Energies

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The issue of freezing often occurs when using all-glass vacuum tube solar water heaters during cold winter seasons, leading to problems such as pipe ruptures and tank leakage. In order to further study the nocturnal heat dissipation and freezing characteristics of these heaters, a three-dimensional transient numerical model of their nocturnal heat dissipation was established. The model simulated the nocturnal heat dissipation process, and experimental validations were conducted through nocturnal temperature drops of the collector and temperature drops of individual tubes without a storage tank. Experimental and simulation results revealed that in clear weather conditions during cold winters in Luoyang, the all-glass vacuum tube solar water heaters experienced freezing issues during the night, with freezing predominantly starting from the bottom surface of the vacuum tubes. The frozen length along the tube wall and the thickness of ice at the bottom section reached up to 1180 mm and 5 mm, respectively. In the absence of a storage tank, the freezing situation was severe, with approximately 4/5 of the individual tubes completely frozen. Under specified operating conditions, different storage tank volumes exhibited varying degrees of freezing in the all-glass vacuum tube solar water heaters. When the volume was increased to 15 L, the temperature drop in the storage tank and the vacuum tubes decreased by 12.1% and 7.6%, respectively. Larger storage tank volumes resulted in reduced freezing risks in all-glass vacuum tube solar collectors. This study provides valuable guidance for the design and application of solar collectors and serves as a reference for the development and application of solar energy utilization technologies.

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Section: Boundary Condition Settingsmentioning

confidence: 99%

The Influence of Storage Tank Volume on the Nighttime Heat Dissipation and Freezing Process of All-Glass Vacuum Tube Solar Water Heaters

Wang

Mao

et al. 2023

Energies

Self Cite

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Techno-economic analysis of solar thermal collector for sustainable built environment

Khargotra,

Kumar,

Kovács

et al. 2023

J Therm Anal Calorim

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India has an abundance of solar energy resources. Nearly 90% of the urban dwellers in different parts of India used electricity for heating water. Using electricity for resident water heating not only contributes to negative environment impact via the emission of a substantial quantity of carbon dioxide but also places a financial burden on households. The examination of solar irradiance, economic feasibility, and hot water demands is crucial in assessing the potential of solar thermal collector (STC) to fulfill hot water requirement. In order to enhance the value of the STC, it is essential for the collector to effectively manage operations with a focus on minimizing cost. To get an optimal heating effect, the present STC is fastened with an obstruction inside the tube. The collector is examined in three distinct seasons to observe temperature variations and the appropriate use of the device during non-operational hours. The recommended average temperatures for summer, rainy season, and winter are 68, 57, and 47 °C, respectively. Additionally, a thorough examination of the economic analysis and payback period for STC was also conducted.

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Thermodynamic assessment of a solar water heater and treatment: an energy–exergy and sustainability analysis

Srivastava,

Sinha,

Choudhary

et al. 2024

J Therm Anal Calorim

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Experimental and simulation on night heat dissipation characteristics and freezing process of evacuated tube solar water heaters

Cited by 5 publications

References 36 publications

The Influence of Storage Tank Volume on the Nighttime Heat Dissipation and Freezing Process of All-Glass Vacuum Tube Solar Water Heaters

The Influence of Storage Tank Volume on the Nighttime Heat Dissipation and Freezing Process of All-Glass Vacuum Tube Solar Water Heaters

Techno-economic analysis of solar thermal collector for sustainable built environment

Thermodynamic assessment of a solar water heater and treatment: an energy–exergy and sustainability analysis

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