ENHANCING THE EFFICACY OF A GROUND SOURCE HORIZONTAL HEAT PUMP BY CARBON NANOTUBES SUSPENDED IN WATER
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Date
2025-01-09
Authors
Khoswan, Ibrahim
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Publisher
An-Najah National University
Abstract
This study explores enhancements in ground source horizontal heat pumps ((GSHHP)) by improving the heat transfer medium through nano-fluids. Researchers have used various types of carbon nanotubes (CNTs) in water. Both functionalized single-walled, Multiwalled carbon nano tubes ((MWCNT)s) with Tween 80 as a surfactant provided optimal suspension, while multi-walled CNTs achieved a 126% increase in thermal conductivity after sonication. Effects of various parameters, like concentration, shape factor, temperature, viscosity, aspect ratio, and added surfactant were studied. The result for (MWCNT) at the thermal conductivity increased with the concentration of (MWCNT) using Tween 80 using 10-60-minute sonication for each sample, no extra suspension would happen beyond that time, and the suspension concentration became saturated. The Thermal conductivity of (SWCNT)-water suspension was less for the same concentration (10% wt.) to reach k(SWCNT)nf= 0.77 W/m.K with a 28% improvement compared to water thermal conductivity kw = 0.6 W/m.K. Those results were better compared to the literature. The results revealed that smaller concentrations of (SWCNT) will be needed, which lowers both capital and running costs. making the system eco-friendlier. The concentration of CNTs influenced the specific heat capacity of the water-based nano-fluid. Higher CNT concentrations led to enhanced thermal conductivity but had mixed effects on specific heat capacity, diverging from typical predictions in the literature((SWCNT)s), ((MWCNT)s) impacted the specific heat differently. (MWCNT)s showed a more noticeable effect on increasing thermal conductivity, though the specific heat enhancement was less pronounced for (SWCNT)s at similar concentrations. Sonication time and the use of a surfactant (Tween 80) affected CNT dispersion in water. A simulation study further verified the experimental findings in both thermal conductivity and specific heat. New models of our experimental data were developed in this dissertation to predict specific heat thermal conductivity enhancement as a function of CNT concentration and nano-fluid properties. These models offered a more accurate estimation of specific heat changes compared to earlier theoretical models which were inaccurate. Also, the simulation of ((GSHHP)) described a qualitative model to rationalize the effects of (CNTs) on nano-fluid conductivity.