Temperature Dependence of iscosity CLAYMORE粘度温度依赖性大剑.docVIP

Lab Two: Vapor Compression (Refrigeration) Tester By Chris Byrne Jason Johnson Kris Koster Haley Nghiem Eric Twiest Mark Wolters School of Engineering Grand Valley State University EGR 475 Heat Transfer Section 01 Instructor: Professor Cutler July 5, 2007 Executive Summary: The purpose of the laboratory investigation was to experimentally determine efficiency of an R-12 refrigeration system under various operating conditions. Thermometers were used to measure the changes in temperature over time at several key points such as the inlet and outlet temperatures of the evaporator and condenser. In addition, refrigerant pressure and flow rate values were monitored at various points in the system. Results indicated that as evaporator temperatures increased, the system exhibited a higher capacity. However, as the compression ratio was increased the isentropic efficiency decreased. Also, measurement error was larger than expected since Qact was greater than Qmax at some locations – a condition that is not physically possible. Under ideal conditions, the system should be run at higher evaporator temperatures and lower compression ratios. Methodology: A digital picture of the refrigeration system diagram is shown in Figure 1. Figure 1: Digital picture of refrigeration system diagram The condenser pressure was set to 5.5 bar (gauge) by adjusting the water flow rate through the condenser. The electric load on the evaporator was set to 200 W. Temperature measurements of the refrigerant were taken at the condenser and evaporator inlet and outlet. Temperature of the water was also taken at the condenser inlet and outlet. The operating pressures of the evaporator and condenser were taken along with the power required to operate the system. This was repeated for loads of 600, 800, and 1200 W on the heating element. The operating pressure of the condenser was also changed from 5.5 to run at 6 and 6.5 bar with the four different heating loads. Data / Discussion: Data wa