A Nanofluid with Superior Thermal Properties

Many industrial processes in the chemical, petroleum, and pharmaceutical industries involve the transfer of heat from one medium to another. Usually, this transfer occurs within heat exchangers, which use thermal fluids to conduct the heat. However, most thermal fluids have thermal properties that require large heat exchangers or pumps. This project will develop a new class of fluids, PCM nanofluids (fluid with a nano-size phase change material (PCM) as the dispersed phase) with superior thermal properties, which will increase the rate of heat transfer in process equipment. During Phase I, two PCM nanofluids, containing nano-sized particles of low-melting metals, were synthesized and characterized. These fluids not only had increased thermal conductivity but also (and more importantly) had heat capacities that increased greatly near the phase change temperature of the metal nanoparticles. For heat transfer in a specific aircraft heat exchanger, calculations suggested that as much as 50 percent more heat could be transferred when the thermal fluid was replaced by one of the PCM nanofluids. During Phase II, a method will be developed to fabricate kilogram-size batches of the PCM nanofluids, and the thermal performance of these fluids will be tested in relevant heat transfer equipment. Commercial Applications and Other Benefits as described by the awardee: PCM nanofluids should enable a reduction in the sizes of heat exchangers and pumps in industrial heat transfer applications. PCM nanofluids also should find use in the thermal management of power electronics and optoelectronics, which is becoming more challenging as the capability and speed of these electronic devices increase and their size decreases. The improved temperature control that is made possible by PCM nanofluids also would benefit the pharmaceutical industry, in which temperature uniformity would improve the quality of the resulting biological products.