Yuanyang Zhao

An Experimental Study on Energy Recovery by a Pelton-Type Expander in a Domestic Refrigeration System

A Pelton-type two-phase expander was developed to replace the throttling valve for energy recovery in a domestic vapor-compression refrigeration system. The Pelton-type expander was designed and fabricated based on thermodynamic and mathematical analysis. It consists of two Laval nozzles and one simplified twin-arc blade impeller. A combined expander-generator prototype was validated in a R-410A domestic refrigeration system and demonstrated a stable operation within a wide speed range of up to 26,500 rpm. Experimental results showed the feasibility of integrating the Pelton-type expander into a domestic refrigeration system. A maximum isentropic efficiency of 32.8% was achieved under the experimental conditions. The relationships between the recovery work, the expander efficiency, and the impeller rotational speed were investigated. The results indicated that the velocity ratio was around 0.17 when the recovery work achieved the maximum value. The results also showed that the increase in the cooling capacity by 6.5% and the coefficient of performance (COP) by 5.4% could be obtained under the testing conditions.

Research on oil-free hermetic refrigeration scroll compressor:

Abstract A prototype of the oil-free hermetic scroll compressor for the application of the refrigeration system of the aviation devices was constructed. The performance of this prototype oil-free scroll compressor was simulated using a thermodynamic model, and was measured. And it was concluded that the prototype oil-free scroll compressor is useful for the refrigeration system of the aviation devices. The simulated results were consistent with the measured ones within less than 10 per cent of the mean deviation. When the evaporating and condensing temperatures were 5 and 55°C, respectively, the volumetric efficiency, discharge temperature, and coefficient of performance were 0.61, 135°C, and 1.45, respectively. The prototype oil-free scroll compressor had been operating reliably for more than 200 h under 85.7 per cent duty cycle and 20 h for 100 per cent duty cycle.

Wrap of cylinder and its effect on main features of rotary vane compressor for automobile air conditioning system

Abstract The rotary vane compressor has been used in the automobile air conditioning system. One of the key factors of its design is the wrap of its cylinder. From the working principle of this type of compressor, it is explained in mathematics why the wrap is composed of four parts: arc of circle, main curve, and two segments of transit curves, and the conditions that the wrap needs to satisfy are derived simultaneously. At the same conditions, we compared to the gas force F p , contact force F nc of the blade head, the force acting on rotor by blades, and the suction volume V s for three kinds of main curves. The wrap composed of trigonometric function can form the biggest value of V s , while the least suction volume V s will be reached as the cubic polynomial is taken. The wrap composed of trigonometric function forms the biggest absolute value of the gas force F p and the middle peak value of the force acting on rotor by blades, while the least absolute value of the gas force F p and the biggest contact force F nc of blade head will be reached as the cubic polynomial is taken. The force acting on the rotor by blades takes the biggest peak value if the main curve is the ellipse curve. The frequency of the force acting on the rotor by blades is the same as the number of blades at the range of the crank angle from 0 to 180°.

Research on the reliability of a scroll compressor in a heat pump system

Abstract The scroll compressor is used in heat pump and refrigeration system equipment because of important features such as its compact size, high efficiency, low vibration and noise level, etc. In the refrigeration cycle the scroll compressor runs smoothly and perfectly, but in the heat pump cycle some problems appear because of deterioration in the working condition. The effect of different factors such as atmospheric condition, electric voltage fluctuation, the configuration of the scroll compressor, etc., on the running reliability of the heat pump system are discussed in this paper, thermodynamic behaviour is examined and some basic design concepts for running reliability of the scroll compressor in the heat pump system are pointed out. Experimental results show that the temperature difference is about 10 K between the gas discharged from the outlet of the compressor and the wound wire of the motor in a high-pressure shell compressor. Calculated and test results show good agreement. The wound wire temperature of the motor in a low-pressure shell is much lower than that in a high-pressure shell scroll compressor. Hence, the low-pressure shell scroll compressor has higher running reliability than the high-pressure one.

A Study on Running Reliability of Scroll Compressor in Heat Pump System

Scroll type of compressor has been used in heat pump & refrigeration system because of its compact size, high efficiency, low vibration and noise level, and excellent running reliability. In the refrigeration cycle the scroll compressor runs smoothly and perfectly, but in the heat pump cycle some troubles appear because its working condition becomes worse. The effect of different factors such as atmospheric condition, electric voltage fluctuation, structure of scroll compressor etc. on running reliability of heat pump system are discussed in this paper. The thermodynamic and aerodynamic behaviors will be emphasized. Some basic design concepts for the running reliability of scroll compressor in the heat pump system are pointed out.Copyright