Aqueous lithium bromide absorption refrigeration systems have been studied in recent years and their advantages like environmental safety and utilization of low-grade energy have been proved. Research on improving their performance has been increasing lately. In this paper, single effect and parallel flow double-effect aqueous lithium bromide absorption refrigeration systems have been studied. Mass, energy, entropy and exergy balances have been used to model the absorption refrigeration systems. Parametric studies have been done to investigate effects of cooling load, evaporator exit temperature, condenser exit temperature, generator vapor exit temperature, absorber exit temperature, solution energy exchanger effectiveness on the performance of the system. The analyses show coefficient of performance and exergetic efficiency of double-effect absorption refrigeration is higher than those of a single-effect refrigeration. The effect of other parameters on performance of both single and double-effect systems have been described in detail in the article.

This paper looks at the advancements made in Solar Power Towers and Heliostat Fields since 2017 and summarizes the current problems in various subsections. Heliostat fields capturing concentrated solar power (CSP) have been looked at for decades as a reliable renewable energy source that can balance out the variability of wind and photovoltaic cells. In recent years, many studies have researched possible improvements in CSP technology. Uniform methods have been developed to better estimate wind loads in various conditions. Gap size and hinge height to cord ratio has been studied to optimize structural strength. Coatings and cleaning schedules have been developed to increase optical efficiency of plants. However, there are many studies that still need to be done to better understand wind and optics for solar power towers. While the Levelized Cost of Electricity (LCOE) of power tower systems has decreased dramatically in recent years, more research and development need to be done to reach the Sunshot Initiative's goal of 5 cents per kilowatt hour [1]. A large area of improvement for future research comes from heliostat manufacturing costs which make up around 40% of energy plant costs. By lowering this cost from the current value of approximately 100/m2to the Sunshot Initiative's goal of50/2, the LCOE of concentrated solar thermal energy will drastically reduce.

A tri-generation plant producing power, heat, and refrigeration has been designed and analyzed. Using solar energy as input. The power side of the plant uses supercritical carbon dioxide (sCO2) recompression cycle. The refrigeration side includes an aqueous lithium bromide absorption system. Thermal energy has been extracted from many places in the plant for heating purposes. A detailed thermodynamics model has been developed to determine performance of the plant for many different conditions. Thermal efficiency, energy effectiveness, and exergetic efficiency of the system has been calculated for different operating conditions. It turns out that the pressure ratio of the recombination cycle and effectiveness of the energy exchanger for transferring energy from the power side to the refrigeration side play important roles.

Supercritical carbon dioxide Brayton (sCO2) cycle has been studied in recent years and its high efficiency and environmental safety has been investigated. One of the most promising sCO2 design is the Recompression cycle described in the Introduction of the paper. In this paper, an effort has been made to optimize operation of a recompression cycle by performing parametric analyses on pressure ratio, split fraction, and maximum temperature. The effects of varying these parameters on thermal efficiency as well as exergetic efficiency have been determined.

Recently, due to the rapid development of the supercritical water-cooled reactor, trans-critical CO 2 heat pump and other technologies, there has been an increasing interest in accurate prediction of convective heat transfer coefficient of supercritical CO 2 under cooling conditions. The main aim of this paper is to give a concise review of heat transfer correlations for supercritical CO 2 cooling in macro-channels (inner diameter larger than 3 mm). Before that the fundamental knowledge about convective heat transfer is first addressed, with an emphasis on heat transfer coefficient.