HVAC Refrigeration Final Practice Exam Questions And Answers Rated 100% Correct!!

Temperature - Answer-Levels of heat, the speed of molecules are traveling British thermal unit - Answer-Amount of heat To raise the temperature of 1 lbs of water 1 degree F Heat flow - Answer-Transfer from hot to cold Conduction of heat - Answer-Heat transfer from one molecule to another within a substance or both substances are in contact with touching Convection of heat - Answer-Heat transfer from one place to another place using water, air or steam Radiant heat - Answer-Heat that passes through the air , not heating the air but heating solid objects which in turns will heat the surrounding area Sensible heat - Answer-it changes the temperature of a substance without a change in its state Latent heat - Answer-(Hidden heat) heat causing a change of state,liquid to vapor/vapor to liquid without a change in temperature Specific heat - Answer-the amount of heat needed to raise the temperature of 1 gram of a substance by 1 degree Celsius Barometer - Answer-A device used to measure atmospheric pressure. 2 types , one mercury known as a Mercury barometer Superheat - Answer-temperature above its saturation point(boiling point) Subcooling - Answer-temperature below its saturation point(boiling point)The refrigerant gives up heat when A.It condenses B.It evaporates C.It compresses D.It vaporizes - Answer-A. It condenses The State of the refrigerant in the suction line should be - Answer-low pressure/low temperature vapor The state of refrigerant entering the condenser is - Answer-high pressure/ high superheated vapor Zero PSIA(pounds per square inch absolute) - Answer-pounds per square inch absolute the absolute scale at zero would be no pressure at all Zero PSIG(pounds per square inch gauge) - Answer-pounds per square inch gauge pressure measurement that references 14.7 psia as its zero point The hermetic reciprocating compressor - Answer-Motor and compressor contained in a welded shell. Cannot be field serviced.Lubricated by the splash method. Low side component, and cooled by suction gas. Semi-Hermetic Compressor - Answer-Can be serviceable(bolted together. Piston heads are located at the top of the compressor. Smaller compressors are splash lubricated, larger compressors are pressure lubricated. Often air cooled. open drive compressors - Answer-Can be directed or belt driven compressors. Must have a shaft seal to prevent leakage. Can be field serviced. Hermetic Rotary Compressor - Answer-Small domestic. Normally hermetic. Mainly air conditioning. To prevent migration there is a check valve on the discharge line. There are two types: Stationary blade & Sliding blade. Capacity control with speed control. Positive displacement liquid slugging - Answer-Liquid refrigerant in the compressor clearance space