| A | B |
|---|
| algorithms | a computer code or set set of instructions to make specific calculations |
| automatic expansion valve (AXV) | a refrigerant control valve that maintains a constant pressure in an evaporator; sometimes abbreviated AEV |
| balanced port TXV | a valve that will meter refrigerant at the same rate when the condenser head pressure is low |
| capillary tube | a fixed-bore metering device; this is a small-diameter tube that can vary in length from a few inches to several feet. The amount of refrigerant flow needed is predetermined and the length and diameter of the capillary tube is sized accordingly. |
| cross liquid charge bulb | a type of charge in the sensing bulb of the TXV that has different characteristics from the system refrigerant. This is designed to help prevent liquid refrigerant from flooding to the compressor at start-up. |
| cross vapor charge bulb | similar to the vapor charge bulb but contains a fluid different from the system refrigerant. This is a special-type charge and produces a different temperature/pressure relationship under different conditions. |
| electronic expansion valve (EXV) | a metering valve that uses a thermistor as a temperature-sensing element that varies the voltage to a heat motor-operated valve |
| error | the signed or mathematical difference between the set point and the control point of a control process that tells whether the control point is above or below the control set point |
| expansion (metering) device | the component between the high-pressure liquid line and the evaporator that feeds the liquid refrigerant into the evaporator |
| external equalizer | the connection from the evaporator outlet to the bottom of the diaphragm on a thermostatic expansion valve |
| feedback loop(s) | the circular data route in a control loop that usually travels from the control medium's sensor to the controller, then to the controlled device, and back into the controlled process to the sensor again as a change in the control point |
| fixed-bore device | an expansion device with a fixed diameter that does not adjust to varying load conditions |
| liquid charge bulb | a type of charge in the sensing bulb of the thermostatic expansion valve; this charge is characteristic of the refrigerant in the system and contains enough liquid so that it will not totally boil away |
| offset | the absolute (not signed + or -) difference between the set point and the control point of a control process |
| pressure limiting TXV | a valve designed to allow the evaporator to build only to a predetermined pressure when the valve will shut off the flow of refrigerant |
| proportional integral (PI) controls | electronic controls that sense and react to the error between the actual and desired states of a system |
| refrigerant receiver | a storage tank in a refrigeration system where the excess refrigerant is stored. Since many systems use different amounts of refrigerant during the season, the excess is stored in the receiver tank when not needed. The refrigerant can also be pumped to the receiver when repairs on the low-pressure side of the system are made. |
| thermostatic expansion valve (TXV) | a valve used in refrigeration systems to control the superheat in an evaporator by metering the correct refrigerant flow to the evaporator. Also often abbreviated TEV. |
| vapor charge bulb | a charge in a thermostatic expansion valve bulb that boils to a complete vapor. When this point is reached, an increase in temperature will not produce an increase in pressure. |
