Empirical Investigation and Analyzing the Thermal Efficiency of Solar Water Heaters Using Evacuated Tubes and Heat Pipes, Considering Multiple Variables and Nanofluid Applications

Document Type : Full Length Research Article

Authors

1 Mechanical Engineering Department, Gujarat Technological University, Ahmedabad, 382424, India

2 Mechanical Engineering Department, Government Engineering College, valsad, 396001, India

Abstract

The effective harnessing of solar radiation offers a promising solution to various environmental challenges, with solar water heaters serving as a prominent method for capturing and converting solar energy into thermal energy. This study evaluates the performance of an Evacuated Tube Heat Pipe Solar Collector (ETHPSC) by examining the effects of water combined with varying concentrations of multiwalled carbon nanotube (MWCNT) nanofluids as the heat pipe's working fluid through a two-step process. A series of experiments were conducted over a six-month period in Navsari, India, characterized by diverse climatic and land cover conditions that significantly influence actual evapotranspiration (AET) rates. The experiments utilized water mixed with MWCNT at concentrations of 0.1%, 0.2%, and 0.3%. The study assessed the efficiency of the solar collector, which was integrated with a compound parabolic concentrator, under varying operating conditions, including three tilt angles (25°, 35°, and 45°), three filling ratios (30%, 40%, and 50%), and three mass flow rates (0.0042, 0.0047, and 0.0056 kg/s). The findings indicate that the collector efficiency improved with the optimal weight concentration of nanofluid and with decreasing mass flow rates. Notably, the ETHPSC with a 0.2 wt.% MWCNT nanofluid, at a tilt angle of 45°, a filling ratio of 40%, and a mass flow rate of 0.0042 kg/s, achieved an efficiency of approximately 64%. The results underscore the importance of optimizing filling ratios and inclination angles to enhance system performance.

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References

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History

  • Receive Date: 04 February 2025
  • Revise Date: 21 July 2025
  • Accept Date: 24 July 2025

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