Multiparameter Analysis in Total Cost Evaluation of a Low Temperature Solar Thermal Assisted Heat Pump for Industrial Applications

The low-temperature solar thermal facility presents important challenges that must be solved to guarantee the heat load and target temperature by means of a parametric analysis that defines the design, operation, and performance of a solar-assisted heat pump. Through the analysis, objectives such as minimum total cost, zero emissions, and a competitive kWh cost can be reached. In this work, a multiparameter study was carried out for a system made up of low temperature solar thermal source and a heat pump to define the operation and performance, using a case study of 2nd generation (2G) bioethanol production. Together, these devices define the system design and must guarantee the operation of the industrial process. One of the system designs seeks to achieve the lowest cost of energy (LCOE = 0.101 USD/kWh) and deliver a heat flow of 637 kW with a temperature of 105°C for 16 h; the heat pump must work with a heat source of 40°C and a coefficient of performance (COP) of 3.5 with the refrigerant R1234ze(z). Another of the system designs seeks to achieve the best performance of the heat pump, which was obtained with a COP= 5.1. Its operating conditions are reached when the heat source is 60°C, and the compression work is 125 kW using the refrigerant R1336mzz(E). The system levelized cost of energy is 0.124 USD/kWh. The importance of this work lies in the fact that a parameter evaluation allows to know the relevant objectives of the system, previous the design to make a custom suit.