BAE4400 Topics in Processing Fall 2006 August 22 through September 21 1 hour credit Dr. C. L. Jones Biosystems and Ag. Engineering

Refrigeration – Lecture 2 Assignment: Read Chapter 11 in Henderson/Perry HW #5 Due 9/19/06, graded papers will be in your mailboxes in 208 on 9/20 Psychrometrics quiz 9/19/06, in boxes on 9/20 Final 9/21/06 GO TO THE CAREER FAIRS!!!!! Dr. C. L. Jones Biosystems and Ag. Engineering

Dr. C. L. Jones Biosystems and Ag. Engineering

System Design: Evaporator The lower the evaporator temperature, the lower the low-side-pressure required and a compressor with greater vol. capacity is required. Determining refrigerant mass flow rate: Example 11.2 pg 340 Dr. C. L. Jones Biosystems and Ag. Engineering

System Design: Compressor Equation 11.17 pg. 341 Compressor displacement = DNS Required compressor power per unit of refrigeration: Equation 11.18 pg 341 Dr. C. L. Jones Biosystems and Ag. Engineering

Examples: Refrigeration system with the following specs: Find: Requires 15 kw Uses R134a for refrigerant Evaporator Temp = -18C Condenser is watercooled w/ 22C water Compressor vol. eff = 83%, thermal eff = 89% Find: A) high and low side pressures B) compressor displacement C) compressor power per unit of refrigeration required D) Refrigerant rate E) COPcooling Dr. C. L. Jones Biosystems and Ag. Engineering

Examples: Refrigeration system with the following specs: Find: Requires 15 kw Uses R134a for refrigerant Ammonia Evaporator Temp = -18C Condenser is watercooled w/ 22C water Compressor vol. eff = 83%, thermal eff = 89% Find: A) high and low side pressures B) compressor displacement C) compressor power per unit of refrigeration required D) Refrigerant rate E) COPcooling Dr. C. L. Jones Biosystems and Ag. Engineering