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Ultrasonic can be used for cold storage defrosting?
Apr 26, 2017

The application of ultrasonic in refrigeration is a new technology in recent years. The defrosting of air cooler plays an important role in the cooling process. Otherwise, it will result in the cooling capacity of the refrigerator is not even cooling or damage. At present, the defrosting method of water, ammonia and electric heating, can cause the temperature rise, while increasing the cooling load, repeated heating and cooling for accelerated frost. Therefore, it is necessary to find a new way to solve the problem of defrosting. When defrosting, must stop refrigeration refrigeration machine, input considerable heat, thermal power except for thermal power is always greater than the general cream in the refrigerator, which will cause the temperature rise (usually rise 3~5 degrees), the defrosting temperature leads to frequent rise will make fruit and vegetable dehydration, aging, direct effects of storage quality. When the ultrasonic acts on the frost layer of the air cooler and the air through the air cooler, the frost layer can be crushed or interfered with the water vapor in the air.

In the study of ultrasonic defrosting of air cooler, the comparative experiments were carried out under the same experimental conditions according to the different frequency range of ultrasonic defrost. Because the cold air machine is a "porous" combination, there are two kinds of resistance to the sound wave, and there are altogether 5 kinds of test schemes. The installation of fixed wheel type 3.7 refrigeration unit, the power capacity of 3.7kW. The bank with the exchange area of a 40m2 fan, and the installation of electronic temperature and relative humidity control and humidifying equipment. In the test base of the cold air machine, using ultrasonic defrosting. The control room was heated by electricity, and the defrosting power was 4.5kW.

All defrost effects are evaluated by the average frost thickness of the continuous running 48h. Comparison of determination, temperature and humidity stability test library and library to control power consumption, continuous 48h evaluation test after stabilization, the size of which to temperature fluctuations in the value of the evaluation, evaluation of moisture to how much water consumption, electricity consumption evaluation with ultrasonic humidifier and electrothermal defrosting pipe. Ultrasonic generator 2, output power 30W. MxI type electronic temperature control instrument 2; YC type humidity measuring instrument 2; vernier caliper 1. Two library operating conditions: control temperature + 0.5 C, relative humidity of 90%, the capacity of 20T.

Test kouin without heating defrosting, the value has stabilized at - 0.5 DEG C and the temperature fluctuation, the peak temperature control library 7 DEG C in heating after defrosting, defrosting after continuous cooling after 20min was restored to plus or minus 0.5 deg..

(1) the frequency range is different, the ultrasonic defrost ability is also different. When f=20kHz, the best effect of compressional wave, when f=15kHz, the best effect of transverse wave defrost.

(2) longitudinal double sound source defrosting effect is slightly worse than the shear wave. The wave propagation direction and air cooling fin vertical fin, the space between a wave conduction resistance, affect the defrosting performance of the liquid transfer tube wave; wave direction and parallel along the longitudinal tube pass more quickly, so the liquid pipe frost on the ratio of the fin in addition to thoroughly. Because the transverse wave can be transmitted along the fin of the cold air machine, the utility model is favorable for removing the frost on the fin. For the cold air blower, the exchange of the cold quantity mainly depends on the fin. The longitudinal and transverse wave although there are differences in the defrosting effect, after continuous operation of 48h, the fins are all did not appear frost blocking phenomenon, there are still 2~3mm clearance between fins, will not affect the heat exchange ability.

(3) cream is better than single sound source in dual source, especially the wave sound sources defrosting effect is best. After the continuous operation of the 48h, there is no frost layer on the fin, and the liquid tube has a little frosting (white). The result shows that the multi sound source makes up the loss of the sound transmission in the network structure.

(4) the control of air cooler at 0 DEG C, relative humidity of 90% cold storage environment, every 8~10h will appear "frost plug" phenomenon, must stop defrosting defrosting in 0.5h, 48h 5, 40m2 cooler defrost heating power 4.5kW, cold storage defrosting and cooling power consumption is 22.5kW. H. By ultrasonic defrosting, whether using P-wave or S-wave, single sound source or two source, into the cold machine defrosting power is only 60W, although the defrosting effect is different, but in the premise of not affecting the heat exchange ability, can work continuously, and the large range of transmission.

(5) and the combined method of defrosting effect is the best, the reason and the sound sources are identical, the longitudinal and transverse "interleaving" to eliminate the air cooler in the "dead", from the view of phenomena, frost free residual air cooler.

(6) the water consumption of the humidifier 48h in the test database is 12L, and the water consumption of the humidifier is 65L, and the water consumption of the 48h is obviously smaller than that of the control.

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