Trane trg-trc005-en manual Condensing Temperature Control

Page 18

period two

Condensers

notes

A reduction in condensing pressure lessens the power required to compress the refrigerant. Unfortunately, if the condensing pressure falls too low, the expansion valve may not be able to produce the flow of liquid refrigerant needed to satisfy the demand at the evaporator. In some systems, as the condensing pressure drops, the compressor suction pressure also drops, resulting in evaporator frosting and possible compressor shutdown due to a low-pressure safety device.

While it is not essential to control condensing pressure to a constant value, provisions should be made to control it within acceptable limits.

Condensing Temperature Control

flow-regulating valve

condenser

condenser water pump

Figure 17

One common method of controlling the capacity of a water-cooled condenser is to vary the rate at which water flows through the condenser.

For example, assume a water-cooled condenser is piped to a municipal water system. To control the capacity of the condenser, a flow-regulating valve is installed on the leaving-water side of the condenser. As the load on the system decreases, the regulating valve senses the lowering condensing pressure. The valve reduces the flow rate of the water until the heat-rejection rate of the condenser balances the system load at an acceptable pressure and temperature.

TRG-TRC005-EN

11

Page 17 Page 19
Image 18
Page 17 Page 19
Contents
Air Conditioning Clinic Refrigeration System Components Comment Card One of the Fundamental SeriesBusiness Reply Mail Refrigeration System Components Preface Refrigeration System ComponentsContents TRG-TRC005-EN Introduction Vapor-Compression RefrigerationRefrigeration Cycle Refrigeration CyclePeriod one Condenser Condensers Air-Cooled CondenserAir-Cooled Condensers Effect of Subcooling Centrifugal Fan Air-Cooled Condenser Evaporative Condenser Evaporative Condensers Water-Cooled Condenser Water-Cooled CondensersCooling Tower Condenser Control Condenser CapacityCondenser Control Condensing Temperature Control Vary Entering Water Temperature Vary Condenser Water Flow RateCooling Tower Bypass Air-Cooled Condenser Control Condenser Flooding ControlCondensers Evaporators Finned-Tube EvaporatorFinned-Tube Evaporators Turbulent Flow Superheat Shell-and-Tube Evaporator Shell-and-Tube EvaporatorsEvaporator Control Evaporator ControlFinned-Tube Evaporator Control Face-Split Arrangement80ºF Intertwined Arrangement Row-Split Arrangement Shell-and-Tube Evaporator Control Expansion Devices Expansion DeviceThermostatic Expansion Valve TXV ControlTXV TXV TXV Operation Psia TXV Superheat Setting Too much superheatAccessories Solenoid ValveSolenoid Valve Period five Liquid-Line Filter Drier Liquid-Line Filter DrierSealed type Moisture-Indicating Sight Glass Moisture-Indicating Sight GlassSuction Line Filter Suction Line FilterHot Gas Muffler Hot Gas MufflerShutoff Valve Shutoff ValveAccess Port Access PortReview Review-Period OneReview-Period Two Air-cooled condenserReview-Period Three Review-Period FourReview-Period Five For more information, refer to the following references Quiz Questions for PeriodQuiz Answers To C To GGlossary Glossary Glossary Trane Company
Top Page Image Contents