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Performance evaluation and optimization of the cooling system of a hybrid thermionic-photovoltaic converter
摘要： Hybrid thermionic-photovoltaic (TIPV) converters are efficient and clean solutions for the direct conversion of thermal energy to electricity, taking advantage of both the photovoltaic and thermionic phenomena. An important hurdle for their efficient operation is the overheating of the PV cell integrated within the TIPV anode, due to partial conversion of the emitted electron and photon fluxes to thermal heat. This obstacle needs to be overcome with an efficient, yet practical, cooler. In this work, a copper plate heat spreader is experimentally tested for TIPV cathode temperatures up to 1450 °C, whilst its performance is also assessed using a validated CFD model for temperatures up to ~2000 °C. A multi-parametric analysis is conducted testing two coolants: i) a water/ethylene glycol mixture at various temperatures (?5–40 °C) and mass flow rates (0.05–0.4 kg·s?1), and, ii) cryogenic liquid nitrogen at a temperature of ?196 °C and mass flow rate of 0.074 kg·s?1. Numerical results reveal that with water/ethylene mixture the PV can withstand heat fluxes up to 360 W·cm?2, without its temperature exceeding 100 °C. For higher thermal fluxes (360–600 W·cm?2), cryogenic liquid nitrogen is found to prevent the PV overheating and, therefore, is an attractive coolant; however, it poses safety concerns due to its possible boiling. Finally, two additional cooling system designs are proposed, a heat sink with straight fins and another with copper pipes, which offer higher heat transfer areas, but are more difficult to manufacture, than the copper plate heat spreader.
关键词： Ultra-high power density,Copper plate heat spreader,Cooling system design optimization,Electronic device,Computational fluid dynamics (CFD)
更新于2025-09-23 15:21:01
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Economic and Resilience Benefit Analysis of Incorporating Battery Storage to Photovoltaic Array Generation
摘要： Power systems with photovoltaic (PV) arrays combined with battery backup storage are becoming increasingly used because of their capability of working in power island mode, especially during grid outages. The problem is to decide the optimal battery sizes for PV + battery systems with given solar array sizes, from both power supply reliability and economical perspectives. An optimization method based on the simulation of system operation during grid interruption is developed to investigate the effects of battery size on system output reliability level of meeting load demand with minimum cost. Case studies are conducted for validation according to actual solar irradiation data, load profiles and realistic power interruption statistics. Sensitivity analysis is also performed to explore how system total cost affects islanding capability of a PV + battery system to supply energy to facilities. The finding shows that the decline of battery price not only reduces the lowest system total cost but also improves islanded system generation reliability. The proposed methodology for optimizing battery capacity added to PV array systems can make them grid-outage resilient and economically viable, which can be utilized as a decision-making tool for future PV + battery system expansion.
关键词： Resilient power systems,Resilience,Photovoltaic power island system,Battery backup systems,System design optimization,Solar power storage
更新于2025-09-10 09:29:36