This module discusses HVAC cooling equipment and the refrigeration cycle. this is where we start linking the ""Loads & Processes"" principles with actual HVAC equipment. By recognizing how a load migrates across HVAC processes such as "heat loops" through heat exchangers, we can begin understanding the equipment. In a refrigeration cycle used for either heating or cooling, refrigerant is the medium, and the vapor compression cycle drives refrigerant through evaporation and condensing process absorbing heat energy from one space, moving, and releasing that energy somewhere else. The vapor compression cycle uses 4 main components to provide mechanical cooling:
1. compressor (work/pressure)
2. condenser (heat discharge)
3. expansion valve (cooling)
4. evaporator (heat absorption)
While DX (direct expansion) air conditioning has refrigerant directly absorbing the load, chillers use chilled water as an intermediate between the load and the evaporator. Water cooled chillers add heat loops that run to cooling towers which cool though heat transfer and evaporative phase change, rather than using air-cooled condensers.
Compressors drive the vapor compression cycle by pressurizing recently evaporated refrigerant. Chillers can "stage" compressors to provide part of full load cooling with scroll, reciprocating, screw, or centrifugal compressors.
Learning Objectives
Upon completion of this course, attendees will be able to recognize:
- Load Management "Heat Loops";
- Refrigerant and the Vapor Compression Cycle;
- Vapor Compression Cycle Components;
- Chillers & Cooling Towers;
- A/C Compressor Types.
