Comparison of Fluid Additive VS. Thermal Paste for Heat Transfer Enhancement in Hybrid PV/Thermal Systems

J. Druzynski, A. Cauchon, V. Thai, M. Anderson
Icarus RT, Inc,
United States

Keywords: Hybrid photovoltaic/thermal, heat transfer


Icarus RT’s Quartet is a hybrid photovoltaic/thermal (PV/T) solar plus storage cogeneration system that enhances PV output, co-generates hot water, and reduces utility costs and emissions for end users. Quartet converts standard PV arrays into hybrid PV/T systems with energy storage, increasing electrical power output by 12-18% and producing thermal energy while addressing PV plus storage limitations. Waste heat is harvested from PV panels via heat extractors, stored in a stratified thermal battery, and harnessed to heat a water supply. The heat extractor attaches to the underside of a commercial solar PV panel and transfers heat from the PV panels to fluid pumped through the extractor. Previous experimentation demonstrated PV panel cooling of 12℃ average. Ensuring maximum heat transfer between the hot PV panel and the working fluid is paramount. Icarus has therefore explored multiple options for material heat transfer enhancement, including nanocoatings, fluid additives, and commercially available thermal pastes. This research was the subject of one of Icarus’ submissions to TechConnect 2022, “Exploring Heat Transfer Efficiency Enhancement for Hybrid PV/Thermal Systems.” Starting in spring 2022, Icarus partnered with a team of senior engineering students from San Diego State University (SDSU) to determine the best fit options for heat transfer enhancement. After extensive analysis including modeling a thermal circuit, Icarus found that two options were the most viable: using a fluid additive such as HydroMX to augment the thermal properties of water, which would otherwise be the working fluid, and applying a thin layer of thermal paste between the heat extractor and the PV panel. This thin layer serves to bridge the insulating air gap, increasing thermal conductivity between the two structures by several orders of magnitude. As part of a pilot line scaling the Quartet system, Icarus RT constructed a 2.5 kW test array at Mira Costa College. Icarus and the SDSU team used this test array to examine the viability of heat transfer enhancement methods in a physical system. The two options in the study were explored both individually and in combination. As of December 2022, the testing is nearly complete, and the data will be processed by January 2023. This paper will analyze the long-term viability of the two heat transfer enhancement methods for inclusion in large-scale Icarus installations. The goal is to create a cost-effective implementation that will increase the heat transferred to the working fluid by at least ten percent and integrate smoothly into Icarus’ existing supply chain.