Duty Control Effect during Crankcase Flow in Automobile ECV at its Crankcase Pressure Port

Electromagnetic control valve; widely known as ECV, is one of the important components used in variable displacement type compressor for air conditioning control system. It controls the compressor operation on the basis of pulse width modulation (PWM) technique that used to encode the information for transmission. PWM technique allows the control of the power supplied from an external controller to the electrical devices, especially to inertial loads. Different pressure ports in ECV, basically acts as the connecting passages through the ECV for air/refrigerant flow functions. Supply of current and duty control is an important issue that highly concerns to the crankcase flow (Pc flow) through the crankcase pressure port of the ECV. In this research paper, effect of duty control is investigated during the Pc flow at the crankcase pressure port of ECV.

Influence of Skewing of Contact Face on Performance of Wave Rotor Refrigerators and Superchargers

As a novel generation of rotational gas wave machines, wave rotor machines such as wave rotor refrigerators (WRR) and wave rotor superchargers (WRS) are unsteady flow devices. In their passages two gas streams (with different pressure or even different phases) comes into direct contact can exchange energy due to the movement of shock waves and expansion waves. A detailed study shows that, when rotor channels open to the high pressure port gradually, the contact face in rotor channels inevitably skews, which is always accompanied with reflection of shockwaves. This causes very large energy dissipation and influences adversely on the refrigeration performance of WRR or the supercharging performance of WRS. In this work, factors such as centrifugal forces, Coriolis forces, gradual channel opening and gradual channel closing, etc, which influence the wave transportation and skewing of shock waves and contact faces are studied by means of computational fluid dynamics and experiments. The skewing of contact faces causes uneven distribution of velocity and large local loss. With rotation Mach number smaller than 0.3, the skewing of contact face can be alleviated. To reduce the adverse influence of rotation Mach number, a smaller rotor channel width or higher rotational speed is necessary. The rotation effect plays an important role for the skewing of gas discontinuities. Both the centrifugal and Coriolis forces of wave rotor cannot be ignored with the Rossby number of 1.3∼3.5. To reduce the skewing loss of contact face, a lower rotational speed seems necessary. The rotation speed of wave rotors has dialectical influences on the skewing of shock waves and contact faces. The jetting width of high pressure port is the key factor of the gradual opening of rotor channels. A feasible way to reduce skewing losses of gas waves is to optimize the ratio between high pressure port width and channel width. The validation experiments have got at least 3∼5% rise of isentropic efficiency for WRRs.

Study on Hydrated Operation Performance of Wave Rotor Refrigerators

Because of bilateral pulse tubes, wave rotor refrigerators (WRRs) have excellent fluidic operation performance. In this work, a WRR experimental rig with throughput of 3×104Nm3/d and expansion ratio 3 for hydrated gases has been built. A number of experiments show that the temperature of low pressure port of WRR has little influence on refrigeration efficiency. This makes possible of maintaining excellent refrigeration efficiency when WRR operating with high-liquid gases. Actual liquid experiments do show the excellent fluidic operation performance: the refrigeration performance remains almost unchanged even if WWR operates with 13.7 %( w) liquid ratio.