Indirect thermosiphon flat‐plate solar collector performance based on twisted tube design heat exchanger filled with nanofluid

Abstract

Summary Stationary solar collector such as flat‐plate collector is a thermal device, which traps solar energy and converts it into heat that can be used in industrial and domestic applications such as water heating. Flat‐plate collector thermal performance enhancement is investigated in this research paper. Two cross‐sectional geometries of the tube in the heat exchanger were investigated; a normal circular tube and a twisted tube were used in the experiment. The aim of the twisted tube exchanger is to enhance the performance of heat transfer of the tubes and to reduce the shell pressure drop; flat‐plate solar collector is the used application to study the heat exchanger performance. Both twisted tubes heat exchanger and normal circular tubes heat exchanger were examined in the same location and conditions with the same solar collector, both were used in the heat exchanger to study their effect, with two different working fluids, which are distilled water and multiwalled carbon nanotube (MWCNT)/water nanofluid. The system shows an increase in the performance when twisted tubes were used in the system compared with the circular tubes in both distilled water and MWCNT/water nanofluid by 12.8% and 12.5%, respectively, with an improvement by 34% for twisted tubes with MWCNT compared with normal circular tubes with distilled water.

Energy and exergy analysis for stationary solar collectors using nanofluids: A review

“…Circulation can be achieved when a heat source alters the density of a particular fluid, which makes the low‐density fluid higher, and when it loses its heat, the same process will circulate. Thermosiphon FPSC is famous because it does not require a mechanical pump, which means that there is no need for an electrical energy source near the collector 141 . Thermosiphon FPSC thermal efficiency is lower than the forced circulation of FPSC because thermosiphon FPSC needs a high‐temperature difference between the inlet and the outlet of the collector to create a circulation.…”

“…However, if the concentration has reached a specific value, the efficiency will begin to decrease; Chougule et al 142 stated that the critical concentration was 0.6 vol% of CNT. Eltaweel et al 141 argued that changing the heat exchanger inside the thermosiphon FPSC from circular tubes to twisted tubes would increase the effectiveness of using carbon‐based nanofluid.…”

“…Thermosiphon FPSC is famous because it does not require a mechanical pump, which means that there is no need for an electrical energy source near the collector. 141 Thermosiphon FPSC thermal efficiency is lower than the forced circulation of FPSC because thermosiphon FPSC needs a high-temperature difference between the inlet and the outlet of the collector to create a circulation. However, the use of nanofluid, such as MWCNT/water as working fluid inside thermosiphon FPSC, can achieve higher thermal efficiency compared to the forced circulation of water as working fluid.…”

Design and Performance Evaluation of a Multi-Temperature Flat Plate Solar Collector

“…Solar water heating systems have shown in many ways to reduce hot water energy consumption significantly. One primary concern that has attracted much research is the solar water heaters' low energy conversion efficiency (Deng et al, 2019;Eltaweel, Abdel-Rehim and Hussien, 2020).…”

Assessment of heat transfer and flow characteristics of a two‐phase closed thermosiphon

“…They concluded that the maximum thermal conductivity (2311 W/m·K) and minimum thermal resistance (0.67 K/W) were obtained in a horizontal situation. Eltaweel et al 24 tested the thermal performance of the flat‐plate solar collector utilizing a twisted tube to enhance the heat transfer. Also, the performance with normal circular tubes was compared.…”