Study On Injector-Boosting-Pressure Organic Rankine Cycle And Its Gas-Liquid Two Phase Injector Performance

Organic Rankine Cycle system shows good performance in utilizing low grade thermal energy, close attention has been paid to the research and application of Organic Rankine Cycle system under the severe energy situation. Gas-liquid two phase injector is a kind of special fluid conveying equipment, gas and liquid exchange mass, momentum, energy in its special flow channel, condensation shock is produced during the exchanging procedure, then liquid with a higher pressure can be obtained at the discharge exit. Gas-liquid two phase injector has no moving parts, there is no noise and leakage during its operation, when applied to Organic Rankine Cycle to replace the traditional mechanical pump, gas-liquid two phase injector can improve the efficiency of Organic Rankine Cycle system.Taking Injector-boosting-pressure Organic Rankine Cycle as research object, gas-liquid two phase injector is applied to Organic Rankine Cycle to form injector-steam-turbine Organic Rankine Cycle system. With injector replacing mechanical pump and hydraulic turbine replacing steam turbine, injector-hydraulic-turbine Organic Rankine Cycle system is formed, these measures can overcome the shortcomings of pump and steam turbine such as occupying large area, leakage and complicated operation, etc. Exergy efficiency and thermal efficiency of two new kinds of Organic Rankine Cycle systems and traditional Organic Rankine Cycle system are theoretically calculated and analyzed. Influence of injector on the performance of Organic Rankine Cycle systems is analyzed. Results show that, under the same condition of evaporator exit, injector-steam-turbine Organic Rankine Cycle system owns the highest exergy efficiency and thermal efficiency, they are 58.11%,15.9% respectively; the exergy efficiency of injector-hydraulic-turbine Organic Rankine Cycle system is below 50%, its thermal efficiency is below 14%. Despite the low energy utilizing efficiency, injector-hydraulic-turbine Organic Rankine Cycle system can be applied to mobile devices and where the installation space is limited. Injector-steam-turbine Organic Rankine Cycle system exergy efficiency and thermal efficiency are the highest, it has good application prospect. The research puts forward a new thoughts to the utilization of low grade thermal energy.For injector-steam-turbine Organic Rankine Cycle system, its performance is studied when using dry working fluids, wet working fluids and isentropic working fluids. Results show that thermal efficiency of injector-steam-turbine Organic Rankine Cycle system is the highest when using isentropic working fluids, at 18.0%; the system net output power is 486.55 kW; when using dry working fluids, steam turbine exhaust steam temperature is too high and causes large amount of energy loss in condenser, which results in relatively lower thermal efficiency and damage to components. When using wet working fluids, the system net output power and thermal efficiency are the lowest.Gas-liquid two phase injector performance experimental platform is set up, organic substance R141b is used as working fluid. The injector’s ability of boosting pressure and entrainment ratio are experimented. In the experiment, the injector outlet pressure is lower than the vapor pressure, the entrainment ratio is small. Experimental results show that when using organic working fluid, in order to realize the injector booster ability and achieve larger entrainment ratio, it needs more work on the injector design and more sophisticated experimental operation.