USAID FINAL REPORT TRNSYS Based Model for Organic Rankine Cycle (ORC) to Produce 1kW Power

The model utilizes TRNSYS 17, a powerful tool for solar thermal power generation, to simulate the behavior of the ORC system. The system consists of a thermal loop and a power loop, with a flat plate solar collector used to heat a glycol/water mixture (50:50) as the heating fluid, and n-pentane used as the working fluid. The simulation results show that the maximum temperature obtained at the collector outlet is 90°C, and the optimum working fluid flow rate is 600 kg/hr. The required inlet pressure for 1 kW power production is 5 bar, and the solar collector area is inversely related to cycle efficiency. The optimum collector area to produce the required power is 16.6 m², and the overall cycle efficiency is 16%. The ORC system is designed to recover heat from low-temperature streams, and the choice of working fluid is critical in determining the system's performance. The characteristics of a good working fluid include chemical and thermal stability, high latent heat of vaporization, isentropic or dry fluid, high density, high specific heat, low cost, and ease of availability. N-pentane is used as the working fluid in this study due to its dry fluid properties and higher heat capacity compared to other refrigerants. The simulation software TRNSYS is used to determine the behavior of the transient system, and the results show that the ORC system is feasible for Lahore, Pakistan. The system can be scaled up to produce any required output, and the weather data for Lahore, Pakistan is used to determine the optimized parameters for the required output power. The ORC system consists of several components, including pumps, collectors, evaporators, turbines, and regenerators. The pumps are controlled by forcing functions, and the inlet flow rates and developed heads are determined. The collector is a flat plate solar collector, and the required area is determined by simulating the thermal loop and determining the collector outlet temperature for the required generator output of 1 kW. The evaporator is a shell and tube heat exchanger, and the overall heat transfer coefficient and heat capacities of the fluids are assumed constant. The source side inlet temperature is 90°C, and the source side flow rate is 2000 kg/hr. The load side inlet temperature is 47°C, and the flow rate is 600 kg/hr. The overall heat transfer coefficient of the heat exchanger is obtained using the log mean temperature difference (LMTD) method. The turbine is a single-stage turbine, and the input pressure to the turbine is kept constant at 5 bar. The enthalpy change can be determined by the equation ΔH = Cp ΔT, and the efficiency of the turbine is determined by the equation Ƞ = WT / ṁ ΔH. The regenerator is a shell and tube heat exchanger, and the condensed organic liquid from the pump is allowed to transfer heat from the output mass flow of the turbine to preheat the liquid and reduce the evaporator load. The simulation results show that the ORC system is a viable option for generating power in remote areas, and the optimized parameters can be determined using the TRNSYS model. The system can be scaled up to produce any required output, and the weather data for Lahore, Pakistan is used to determine the optimized parameters for the required output power.