Browsing by Autor "Andrew Martin"

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Biogas based polygeneration plant options utilizing dairy farms waste: A Bolivian case
(Elsevier BV, 2019) J. Villarroel-Schneider; Brijesh Mainali; Jaime Martí-Herrero; Anders Malmquist; Andrew Martin; Lucio Alejo
Performance Analysis of a Small-Scale Biogas-Based Trigeneration Plant: An Absorption Refrigeration System Integrated to an Externally Fired Microturbine
(Multidisciplinary Digital Publishing Institute, 2019) J. Villarroel-Schneider; Anders Malmquist; Joseph Adhemar Araoz Ramos; Jaime Martí-Herrero; Andrew Martin
Trigeneration or combined cooling, heat and power (CCHP) systems fueled by raw biogas can be an interesting alternative for supplying electricity and thermal services in remote rural areas where biogas can be produced without requiring sophisticated equipment. In this sense, this study considers a performance analysis of a novel small-scale CCHP system where a biogas-fired, 5 kWel externally fired microturbine (EFMT), an absorption refrigeration system (ARS) and heat exchangers are integrated for supplying electricity, refrigeration and hot water demanded by Bolivian small dairy farms. The CCHP solution presents two cases, current and nominal states, in which experimental and design data of the EFMT performance were considered, respectively. The primary energy/exergy rate was used as a performance indicator. The proposed cases show better energy performances than those of reference fossil fuel-based energy solutions (where energy services are produced separately) allowing savings in primary energy utilization of up to 31%. Furthermore, improvements in electric efficiency of the EFMT and coefficient of performance (COP) of the ARS, identified as key variables of the system, allow primary energy savings of up to 37%. However, to achieve these values in real conditions, more research and development of the technologies involved is required, especially for the EFMT.
Thermodynamic and exergetic analyses of a biomass-fired Brayton-Stirling cogeneration cycle for decentralized, rural applications
(Elsevier BV, 2023) Luis A. Choque Campero; Wujun Wang; Andrew Martin
Access to electricity in many remote rural areas of the world is wanting and often relies on decentralized concepts that are environmentally detrimental, costly, and unreliable. The purpose of this study was to examine an approach to meet this need that is based on an external biomass-fueled cogeneration system incorporating combined cycles for maximizing efficiency while ensuring robust operation. Specifically, the first and second laws of thermodynamics were analyzed in a system composed of a Brayton-Stirling cycle and a water boiler to compare efficiency, heat and electricity generation under three different power layouts of cogeneration for applications in the range of 100–200 kW electrical power output. The results show that overall efficiency is maximized at 85% with a hybrid power layout for cases where the turbine inlet temperature is 1273 K, the pressure ratio is 0.4, the regenerator effectiveness is 0.95, and the dead volume of the Stirling engine is 0.3. These findings provide a basis for implementing cogeneration systems to improve the reliability and robustness of power systems for rural electrification.