Proposal for an advanced heat source assembly for the Isotope Brayton Power System. Volume 1. Technical program and statement of work

This study aims to evaluate the performance of an organic Rankine cycle (ORC) power system adopting dual expanders in parallel by experiment. A dual-expander ORC system was designed to provide competitive advantages over a general single expander ORC system in typical applications with large thermal fluctuation of heat sources such as solar heat, marine waste heat, and etc. The ORC system consists of two scroll expanders installed in parallel, a hydraulic diaphragm type pump to feed and pressurize the working fluid, R-245fa, two plate heat exchangers for the evaporator and the condenser, and two generators with shaft power torque meters. The two scroll expanders were modified from two oil-free air scroll compressors, and were tested in the ORC loop with R245fa. The maximum isentropic efficiency of each expander was measured about 53%, and the shaft power was reached to about 2kW. The hot water was used as heat source, and the water temperature was controlled up to 150 °C by the 100 kW-class electric heater. A circulating air-cooled chiller was utilized for the control of the cooling water temperature. In order to determine the static performance of the system, efficiencies and shaft powers were measured with 130 °C heat source temperature. In addition, performance tests were conducted with various working fluid mass flow rates to control pressure ratios. The characteristics and total thermal efficiency of the dual parallel expander ORC system and optimal operating modes are addressed.

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Analysis of the Zero-Pressure-Difference Point and Determination of the Pump Head in Distributed Power System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.353-356.2625 ◽

2013 ◽

Vol 353-356 ◽

pp. 2625-2630

Author(s):

Yong Zheng Fu ◽

Ming Liu Xu ◽

Yang Jiao

Keyword(s):

Energy Consumption ◽

Heat Source ◽

Power System ◽

Critical Point ◽

Pressure Difference ◽

Total Output ◽

Distributed Power ◽

Distributed Power System ◽

Pump Head ◽

Transmission Energy Consumption

Using pressure diagram to analyze the pressure distribution of distributed power system when the zero-pressure-difference point is in different positions. Conclusions can be drawn as follows: the zero-pressure-difference point should be between the critical point and heat source to eliminate the energy consumption of regulators. And as a result the transmission energy consumption of the system becomes lowest. When the zero-pressure-difference point is in different positions between the critical point and heat source, arrangements of pumps of the system are different. But the total output power of the pumps is the same. The zero-pressure-difference point and the schemes for pump head can be conveniently determined by graphical method like pressure diagram or numerical method.

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