Recovery of Partial Heat of Pyrolysis From Solar Thermal Collector for Thermochemical Conversion of Food Waste

Abstract

Biomass conversion processes can be energy intensive. There is a need to seek renewable sources to meet such energy demand. In this study, a partial heat of pyrolysis from a concentrated solar power (CSP)-based solar heat collector is modeled. A numerical investigation of the flow in the heat collector element (HCE) of the CSP is performed. By using the finite volume formulation, the fluid flow behavior within the pipe of the HCE is simulated to determine the thermal absorption, heat losses, and efficiency obtainable from the solar irradiation on the receiver tube. Monte-Carlo Ray-tracing based software, soltrace, is used to estimate the incident heat flux on the LS-2 receiver with an average direct normal irradiance (DNI) value, based on a comparative performance study of three types of molten salts (i.e., the heat transfer fluids (HTFs)). The performance of three kinds of the LS-2 HCE (i.e., vacuum, air-filled, and evacuated types) is also analyzed in terms of heat loss and efficiency measurements respectively. HITEC provides the best performance in terms of stability in delivering the partial heat of pyrolysis for the gasification of food waste on moderate velocities of 0.75—2 m/s. Also, the pyrolysis of the feedstock is proposed with an operating feedstock rate of 0.19 kg/s and 0.17 kg/s for lower heating value (LHV) and higher heating value (HHV), respectively. It is anticipated that the combined heat of pyrolysis from the proposed dual heat cycle, comprising both the CSP and a biogas plant, will provide a solution to the demand for alternative power from biomass energy conversion.