标题：Heat transfer and economic analyses of using various nanofluids in shell and tube heat exchangers for the cogeneration and solar-driven organic Rankine cycle system
摘要：This project attempts to evaluate the effect of nanofluids on thermal performance and the economic parameters of shell and tube heat exchangers. First, two thermodynamic processes including combined heat and power (CHP) system and solar-driven organic Rankine cycle (ORC) are simulated using the Aspen HYSYS. The CHP and ORC systems can produce 25 MW and 175.8 kW of electrical power, respectively. Thereafter, to use the nanofluids in the heat exchangers of these systems, the thermophysical specifications are modeled in the MATLAB software and validated with previous investigations. For this purpose, four kinds of nanofluids consisting of Al2O3/H2O, TiO2/H2O, Cu/H2O and Ag/H2O are utilized. According to the results, by adding the nanoparticles to the base fluid, the thermal conductivity, viscosity, heat transfer coefficient and density increase and the heat capacity reduces. The economic assessment and parametric analysis on concentration of the nanoparticles are conducted. The variations of concentration of nanoparticles are taken to be 0.5–4%. It was found that in ORC system, by employing 1% concentration of Ag/H2O, Cu/H2O, Al2O3/H2O and TiO2/water nanofluids, the overall cost is reduced by 3.1%, 1.9%, 1.2% and 0.9%, respectively. Also, in CHP system, at a concentration of 2% for Ag/water, Cu/water Al2O3/water and TiO2/water nanofluids, the total cost decreases by 4.4%, 3%, 1% and 0.5%, respectively. It was denoted that the utilization of nanofluids in thermodynamic cycles can considerably reduce the total cost of heat exchangers and the whole process.
