Energy, Conventional and Advanced Exergy Analysis of Low Temperature Geothermal Binary-flashing Cycle Using Zeotropic Mixtures

Due to deep utilization of geobrine and high net power output, binary flashing cycle (BFC) is deemed to be the future geothermal energy power generation technology. The BFC using R245/R600a zeotropic mixtures is presented in this paper. The thermodynamic model of the system is built, and energy, conventional and advanced exergy analysis are carried out, to reveal the real optimization potential. It is demonstrated that the optimal composition mass fraction of R245fa and dryness of working fluid at the evaporator outlet ranges are 0.30~0.50 and 0.40~0.60, considering the thermodynamic performance and the flammability of the mixtures, simultaneously. Conventional exergy analysis indicates that the maximum exergy destruction occurs in condenser, followed by expander, evaporator, flashing tank, preheater, high-pressure pump and low-pressure pump. While the advanced exergy analysis reveals that the expander should be given the first priority for optimization, followed by condenser and evaporator. The BFC has a large potential for improvement due to higher avoidable exergy destruction, about 48.6% of the total system exergy destruction can be reduced. And the interconnections among system components are not very strong, owing to small exogenous exergy destructions. It also demonstrates the effectiveness of advanced exergy analysis, and the approach can be extended to other energy conversion systems to maximize the energy and exergy savings for sustainable development.

Distribution parameter modeling and experimental verification of constant-pressure variable displacement pump

To provide a precise model of dynamic components in the constant pressure pump, and to improve the accuracy of dynamic calculation of the constant-pressure hydraulic system in its design stage, the research undertook mapping on a particular constant pressure pump and determined its basic structural parameters. Then, with the AMESim software, the research adopted separate structures from the level of basic components to establish the model of single-piston pump, the model of variable displacement pump, and the model of adjustable mechanism for the swashplate, respectively. The three models were combined with the constant-pressure variable displacement pump before it was encapsulated in a super component. By controlling the flow discharge of the constant pressure pump, and by switching on and off the constant pressure valve with the internal and long-distance pressure control, the research undertook the simulative test and the corresponding experimental test on the characteristics of pressure response of the constant pressure pump. The results of both tests agreed well with each other. Thus, it verifies the precision of the established constant pressure pump model in performing accurately in response design and analytical calculation.

ANALYSIS OF FUEL QUALITY EFFECT ON THE LIFE TIME FROM HIGH-PRESSURE PUMP OF ENGINE MTU 12 V 4000 M 71

Fuel is one of the important components in the combustion process. A good fuel is a clean fuel where the fuel is colorless, watery, has a high flash point, it can ignite spontaneously at a temperature of 350ºC, and has a specific gravity of about 0.82-0.86. On the other hand, KRI Kelabang-826 is an Indonesian republic warship that functions as a patrol boat. This causes the ship to have a medium duty engine, the MTU 12 V 4000 M 71 engine. This engine itself is a sophisticated engine because it uses common rail technology with a High-Pressure Pump as the supplying pump. This pump is very susceptible to damage, this is proven by not achieving the life time of the High-Pressure Pump which is 7500 Running Hours or once a W5- level maintenance. This is caused by poor quality of fuel, where the fuel used contains water and impurities. Therefore, the preventive ways are needed in order to achieve the life time of this High-Pressure Pump component. Keywords: Fuel Quality, MTU 12 V 4000 M 71, High-Pressure Pump, and Condor Class.