• Energy Research

Abstract Energy consumption and related environmental issues are one of the most important concerns in the world, and contribution of building sector in total energy consumption is extremely large. Two-stage desiccant cooling system has become a powerful alternative to the traditional systems because of its benefits such as effective removal of the air latent heat, low greenhouse gases emissions and low grade thermal energy use. In this paper, different regeneration methods for two-stage desiccant cooling systems have been simulated. New regeneration configuration for desiccant wheels causes thermal coefficient of performance and exergy efficiency rise by 15.5% and 21.4%, and reach 0.72 and 0.58, respectively. It is still more important that the proposed regeneration configuration leads to a decrease in required regeneration temperature 4.1 °C which improves the potential of the system for application of solar energy and waste heat. Moreover, the effect of different combination of regeneration temperatures on system performance have been studied. It is found that, for each system configuration, there is an optimum combination of regeneration temperatures for achieving the maximum thermal coefficient of performance and exergy efficiency.

Abstract In hot and humid regions, vapor-compression cooling systems impose high power demand to grid and increase peak of the load. While thermally activated cooling systems can be a sustainable solution, they are even more beneficial when driven by waste heat. In this paper, a multi-generation system including gas engine, desiccant cooling system and thermal desalination system is studied under three different weather conditions. In the desiccant system, two innovative cycles are applied in which the humidity of regeneration air is higher than conventional systems. Therefore, dew point temperature will be high enough for water condensation. The results show it can compensate for 121% of consumed water in humid areas. Moreover, thermal COP is within range of 0.61–1 in studied cities. While the cooling system uses the jacket water heat, desalination system is powered by the flue gasses. It can annually desalinate 1,122 and 1,817 m3 water by heats of the engines with powers of 33 and 55 kVA. Economic investigation shows levelized cost of cooling is within range of 1.5 to 20 US cents depending on the system size and weather conditions. Besides the water price, the difference between electricity and gas prices plays a key role in system economic feasibility.

In this study, the thermodynamic behavior of a combined cycle power plant with integrated solar-driven inlet air cooling was simulated for Tehran, Phoenix, and Houston during warm-hot seasons. A considerable reduction in the output power was realized during hot ambient conditions due to the lower density of the air and lower mass flow rate to the turbines. The output power decreases from 306.6 to 260.8 MW as ambient temperature increases from 15 to 45 °C. This research focuses on utilizing solar cooling systems to achieve low inlet air temperature to generate high-electricity yields. Four different types of solar collectors and two different absorption chiller units were selected and simulated for each city to achieve the required goal. It was identified that integrating a solar inlet air cooling (SIAC) system can avert the reduction in output power with no impact on efficiency. The humid climatic condition in Houston and the low electricity cost in Tehran posed some challenges in designing a feasible SIAC system. However, by optimizing the solar collectors and cooling capacities, an optimal solution for utilizing inlet air cooling in humid climates is presented. In terms of overall impact, the evacuated flat plate collector (EFPC) coupled with a double-effect absorption chiller displayed the best economic performance among the four variants under study. In Phoenix, this combination can maintain output power during hot days with a DPR of 2.96 years.