OVERHEATING MEASURING DEVICES
Overheating plays an important role in the refrigeration and air conditioning service. For example, thermostatic expansion valve works on the principle of overheating. In charging the capillary tube systems, overheating of the measurements should be watched carefully. Suction line superheat indication of whether liquid refrigerant flooding of the compressor suction-side. Dimension zero overheating is a definite indicator that the fluid reaches the compressor. Measuring 6 to 10F (-14.4-12.2C) for the expansion valve system and 20F (6.7C) capillary tube systems indicates that the entire refrigerant evaporates before entering the compressor.
Overheating at any time in the cooling system was found with the first measurement of the actual temperature of the refrigerant in the moment with the electronic thermometer. Then refrigerant boiling-point is connecting the composite pressure gauge system and read the boiling point from the center of the gauge.
The difference between the actual temperature of boiling of overheating. If overheating zero, the refrigerant must be boiling inside. Then, there's a good chance that some of the refrigerant is still liquid. If overheating above zero, at least 5F or better, refrigerant, probably past the stage of boiling, and all pairs.
The method of measurement of overheating described here has obvious disadvantages. If there is no attachment to excessive pressure in the point system, where you measure of overheating, the hypothetical boiling point cannot be found. To determine the overheating at such a point, you can use the following method. This method is particularly useful for measuring the superheat of refrigerant vapour at the suction line.
Instead of using excess pressure, the boiling temperature of the refrigerant in the evaporator can be determined by measuring the temperature of the line after the expansion valve where boiling, energetic. This can be done with any electronic thermometer. Cm. Fig. 1-32. As the refrigerant is heated through the evaporator and suction line, the actual temperature of the refrigerant can be measured at any point along the suction line. The comparison of these two temperatures gives overheating measurement sufficient for work in field conditions, if a distributor dosing is used or the evaporator is very large with a large number of pressure drop in the evaporator.
Using the meter is shown in Fig. 1-33, you can read overheating directly using the drop of the temperature object. Strap one end of the differential sensor at the exit from the metering device. The belt and the other end to a point on the suction line, where overheating measures should be taken. Turn on the meter differential temperature and superheat will directly read the meter.