A New Direction for Distributed-Scale Solar-Thermal Co-Generation

The goal for a distributed-scale solar-thermal co-generation (DSSTC) design is a realistic solar-thermal heat and electrical generation system for residential, commercial, and industrial applications. A holistic design approach is accomplished by advancing and adapting knowledge from several fields of study. The research includes solar irradiance modeling from the atmospheric science and engineering perspectives, thermal-fluids design of heat engines and the search for working fluids, organic Rankine cycle design, system design optimization. Previous works focus only on one or two of these fields, while neglecting the design requirements of one or more of the others. No work has shown that DSSTC can be cost effective despite functioning designs as early as the late 19th Century. This work evaluates design requirements by synthesizing fundamentals in each field to build a complete analysis. Design methodology and cost effectiveness are fundamentally advanced, while identifying key future research needs. This is achieved by building a complete system simulation that accounts for size, part-load and realistic solar variability, which naturally lead to advances in the fundamental fields. Solar irradiance modeling for solar thermal collector is advanced by evaluating the testing standard and demonstrating the benefit of angular distribution sky radiance modeling. The search for working fluids is extended from the heating, ventilation, and air-conditioning equipment field to organic Rankine cycle heat engines. The cost of DSSTC is compared to Photovoltaic (PV) on an electricity generation and heat production basis. By properly accounting for both the anisotropy of the sky and the collector, solar model prediction is improved. Adapting the fluid search criteria finds few current fluid options that met both thermodynamic The goal for a distributed-scale solar-thermal co-generation (DSSTC) design is a realistic solar-thermal heat and electrical generation system for residential, commercial, and industrial applications. A holistic design approach is accomplished by advancing and adapting knowledge from several fields of study. The research includes solar irradiance modeling from the atmospheric science and engineering perspectives, thermal-fluids design of heat engines and the search for working fluids, organic Rankine cycle design, system design optimization. Previous works focus only on one or two of these fields, while neglecting the design requirements of one or more of the others. No work has shown that DSSTC can be cost effective despite functioning designs as early as the late 19th Century. This work evaluates design requirements by synthesizing fundamentals in each field to build a complete analysis. Design methodology and cost effectiveness are fundamentally advanced, while identifying key future research needs. This is achieved by building a complete system simulation that accounts for size, part-load and realistic solar variability, which naturally lead to advances in the fundamental fields. Solar irradiance modeling for solar thermal collector is advanced by evaluating the testing standard and demonstrating the benefit of angular distribution sky radiance modeling. The search for working fluids is extended from the heating, ventilation, and air-conditioning equipment field to organic Rankine cycle heat engines. The cost of DSSTC is compared to Photovoltaic (PV) on an electricity generation and heat production basis. By properly accounting for both the anisotropy of the sky and the collector, solar model prediction is improved. Adapting the fluid search criteria finds few current fluid options that met both thermodynamic as well as health, safety, and environmental requirements. There exists a possibility of finding new working fluids for higher temperature organic Rankine cycle applications. The fluid search process is incomplete and remains future work. System simulation at four levels of detail are completed. Increasing detail lowers predicted energy yield and reveals additional design problems of increasing complexity. DSSTC comparison to PV shows that PV is more cost effective for electricity only production and DSSTC is more cost effective for heat production in the 150–250◦C range, which is the N–S XCPC marketed range. It remains unclear which system, if either, can be cost effective for both electrical and thermal energy needs, although PV is making progress by competing in space heating and domestic hot water thermal end uses. Additional simulation is required to evaluate the possible benefit of using DSSTC in a co-generation capacity