Scroll compressor

Abstract: Refrigerant vapor-injection technique has been well justified to improve the performance of systems in refrigeration applications. However, it has not received much attention for air conditioning applications, particularly for air conditioning in hot climates and for heat pumping in cold climates. In this study, the performance of an 11 kW R410A heat pump system with a two-stage vapor-injected scroll compressor was experimentally investigated. The vapor-injected scroll compressor was tested with the cycle options of both flash tank and internal heat exchanger configurations. A cooling capacity gain of around 14% with 4% COP improvement at the ambient temperature of 46.1 °C and about 30% heating capacity improvement with 20% COP gain at the ambient temperature of −17.8 °C were found for the vapor-injected R410A heat pump system as compared to the conventional system which has the same compressor displacement volume.

Abstract: This paper presents a detailed model for the compression process of a scroll compressor, which is used for investigating a compressor's performance under different operating conditions and subject to design changes. Upon defining the compressor chambers as suction chambers, compression chambers and discharge chambers, a geometry study was conducted and the governing mass and energy conservation equations were developed for each chamber. Models for the refrigerant flow in the suction and discharge processes, radial and flank leakage, and heat transfer between the gas and scroll wraps were combined with the conservation equations. The state of the refrigerant changes with a period of angle 2π, and thousands of step are used to solve the governing differential equations during each period. It is assumed that in each step the compressor is in steady state. Since the differential equations for the different chambers are coupled, all these equations are solved simultaneously using a nonlinear equation solver. A description of the corresponding computer code and some results are included in this paper. Verification of the compression process model can be referred to that of the overall model, which is described in Chen et al. [Chen Y, Halm N, Braun J, Groll E. Mathematical modeling of scroll compressors—part II: overall scroll compressor modeling. International Journal of Refrigeration 2002;25(6):751–764.].

Abstract: A control for a refrigeration system serviced by a special pulse width modulated compressor (30) coupled to a condenser (32)and evaporator (42). The system can be of the distributed type wherein the condenser (32) and compressor (30) may be coupled to service a group of adjacent refrigeration cases, wherein each case would have its own evaporator (42). A controller (52) is coupled to a load sensor (58) for producing a variable duty cycle control signal (54) in which the duty cycle is a function of demand for cooling. Moreover, fuzzy logic technique may be utilized in order to provide self adaptive tuning control for the system.