Comprehensive thermodynamic and operational optimization of a solar-assisted LiBr/water absorption refrigeration system

Absorption cooling systems have been investigated for many years due to their ability to use low-grade heat instead of electricity as the energy source. The aim of this work is to advance the performance of a single-effect Lithium bromide/water absorption cooling system. Taking the generator and evaporator temperatures as variables, the system is optimized to maximize exergetic and energetic efficiencies at different operational conditions using a multi-objective–multi-variable Genetic Algorithm. The Group Method of Data Handling neural network approach is adopted to derive correlations between the design variables and operational parameters. Finally, the system is coupled to evacuated tube solar collectors and compared to a similar system. The results reflect a maximum improvement in energetic and exergetic efficiencies of about 9.1% and 3.0%, respectively. This translates into savings of 187 dollars for every square meter of solar collector at present time. This improvement is achieved by decreasing the mean temperature of the generator by 6.2 °C and increasing the mean temperature of the evaporator by 1.6 °C. In the case of applying low-grade heat such as solar energy, it brings about both an improvement in the thermodynamic performances and a reduction in the generator temperature

Techno-economic assessment and optimization of a solar-assisted industrial post-combustion CO2 capture and utilization plant

This paper studies the techno-economic feasibility of the solar-assisted regeneration process of the largest industrial CO2 removal monoethanolamine-based plant in Iran. The plant incorporating parabolic troughs is modelled using System Advisor Model software and the weather data are derived from the European Commission''s Photovoltaic Geographical Information System. Sensitivity analyses are realized to evaluate the effect of important parameters, i.e., the solar multiple and the hours of storage, and to reveal the optimum case. The studied impacts are linked to the overall net energy generation and the levelized cost of heat (LCOH). The optimum case is found to have a solar multiple of 3.1 and 18-hours of storage, resulting in a solar share of 0.7 and a LCOH of 3.85 (¢/kWh). When compared to the base case (solar multiple of 2 and 6 h of storage), the optimum solution results in a similar LCOH but it achieves the generation of an additional 16, 112 MWhth annually. The thermal energy supplied by the solar system leads to an annual reduction in the natural gas consumption of approximately 3.8 million m3 that results in a CO2 emission reduction of 7.1 kton. © 2021 The Author

Auslaendische Arbeitnehmer in Wiesbaden Situation auf dem Arbeitsmarkt ; Materialien zum Auslaenderbericht

UuStB Koeln(38)-870106840 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

A solar-driven 5th generation district heating and cooling network with ground-source heat pumps: a thermo-economic analysis

District Heating and Cooling is considered an efficient solution to address the thermal energy demand of the building sector and reduce its environmental impact. In this paper, a 5th generation bidirectional heating/cooling network is designed and modelled. The network is coupled with water-to-water heat pumps, ground heat pumps and a photovoltaic field and is designed to meet the energy requirements of a 50-building district in the city of Leganés (Madrid). All components are modelled in TRNSYS 18. The studied network achieves a primary energy saving index of 64% and reduces the CO2 emissions by 76% relative to the current situation. The economic analysis of the system results in the relatively long payback period of 33 years, mainly due to the high costs of excavation and the installation of the heat pumps and pipes. With the current design, the photovoltaic field meets only 30% of the electricity demand of the district. However, additional energy storage could help align the power production with the actual power demand better and avoid grid balancing issues. The inclusion of other types of thermal energy consumers would also enhance the performance of the network by increasing the simultaneity between cooling and heating demands

A comparative life cycle assessment for solar integration in CO2 capture utilized in a downstream urea synthesis plant

This study assesses the environmental performance of an existing petrochemical plant that produces urea fertilizer and liquid ammonia. In urea production facilities, ammonia is always in excess. This excess can be converted back to urea if reacted with CO2 in an ammonia reformer. Such a process can boost the production capacity of the plant without the need for further investment in major equipment, like reformers and reactors. In the plant studied here, a CO2 capture and utilization unit (CCU) is used to capture CO2 from the stack of the ammonia plant to further enhance urea production. The unit recovers about 5500 kg of CO2 per hour. The environmental performance of the petrochemical plant is evaluated with and without CO2 capture and under solar-assisted operation. Although the solar-assisted operation performs better than the plant with CCU in many environmental parameters, the differences between the two cases are relatively small. The outcomes of the life cycle assessment show that the carbon footprint of the solar-assisted operation with CCU is about 10% lower than that of the plant without CCU. In addition to some environmental benefits of the CCU plant, the plant with carbon capture increases the urea production by about 8%