Thermodynamic analysis of lithium bromide absorption chiller driven by geothermal energy
The use of geothermal energy as a heat source to drive vapor absorption chillers has been receiving more interest. Geothermal energy is sustainable, economically viable and environmentally friendly. Absorption chillers powered by geothermal energy are still in their development phase. In this work, a lithium bromide absorption chiller operated with a geothermal heat source will be thermodynamically analyzed. The focus will be on the solution heat exchanger performance, in particular, the effect of geothermal heat source fluid temperature as well as mass flow rate on the absorption chiller coefficient of performance (COP). The effectiveness of the solution heat exchanger will be also studied and evaluated. Preliminary results showed that as the pressure in geothermal water vapor separator increased from 0.23 to 0.45 MPa, the absorption chiller cooling load increased by 28% while the COP decreased by only less than 1.4% at the same condenser pressure.
Geothermal energy use in absorption precooling for Claude hydrogen liquefaction cycle
Abstract We propose an integrated system that consists of an ammonia-water absorption refrigeration cycle for the precooling of hydrogen, and the Claude cycle for the liquefaction of hydrogen. Geothermal energy supplies heat to the generator of the absorption system. A liquid geothermal source available at 200 °C at a rate of 100 kg/s is considered. The system is analyzed thermodynamically by the first and second laws using appropriate performance parameters. Under realistic operating conditions 39,080 kW heat can be supplied by geothermal water in the absorption refrigeration system. Hydrogen gas can be cooled to −26.9 °C at a rate of 29.53 kg/s in the absorption unit. The coefficient of performance (COP) of the ammonia-water refrigeration system is determined to be 0.556 with an exergy efficiency of 67.0%. The COP of the Claude liquefaction system is 0.0120 and its exergy efficiency is 67.3%. For the overall system, the COP and exergy efficiency are 0.162 and 67.9%, respectively. Also, precooling hydrogen gas in an absorption refrigeration cycle powered by geothermal heat decreases the work consumption in the liquefaction process by 25.4%.
Research on Control and Planning of Soft-Wing UAV for Haze Removal
The existence of fog and haze has caused great pollution to the environment. The research of removing haze is a hot topic in recent years. In this paper, a special haze removal algorithm based on Soft- Wing UAVis proposed. In this algorithm, two track control strategies are designed based on the Soft-Wing UAV model transfer function. A SIMULINK platform based mathematical model of Soft-Wing UAV is built to testified effectiveness of the two track control strategies. An autonomous ergodic-planning algorithm with greedy strategy and foldback algorithm for Soft-Wing UAV is designed. Within the algorithm, the haze regional has been modelled, the cost matrix is constructed, and the planning and ergodic strategy is proposed. Finally, the experimental results validates the reliability of the algorithm in the application of haze removal with the proposed evaluation Index.