CN109140834B - Defrosting system and defrosting method for evaporator tube bank of refrigeration house - Google Patents

Defrosting system and defrosting method for evaporator tube bank of refrigeration house Download PDF

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Publication number
CN109140834B
CN109140834B CN201810800041.7A CN201810800041A CN109140834B CN 109140834 B CN109140834 B CN 109140834B CN 201810800041 A CN201810800041 A CN 201810800041A CN 109140834 B CN109140834 B CN 109140834B
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defrosting
evaporator
thickness
frost
calandria
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CN109140834A (en
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曹玉春
沈冰燕
李森
周年勇
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Changzhou University
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Changzhou University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B39/00—Evaporators; Condensers
    • F25B39/02—Evaporators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
    • F25B47/02—Defrosting cycles
    • F25B47/022—Defrosting cycles hot gas defrosting

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Defrosting Systems (AREA)

Abstract

The invention provides a defrosting system and a defrosting method for a refrigerator evaporator calandria, which invent a defrosting technology based on the combination of microwave defrosting, physical defrosting and chemical defrosting, can avoid a large amount of manual labor, reduce the influence of labor cost and personnel warehousing on cooling capacity consumption, simultaneously avoid the influence of microwaves on a refrigerant in the evaporator calandria, and effectively improve defrosting efficiency and energy utilization rate.

Description

Defrosting system and defrosting method for evaporator tube bank of refrigeration house
Technical Field
The invention relates to the technical field of refrigeration equipment of a refrigeration house, in particular to a defrosting system and a defrosting method for a discharge pipe of an evaporator of the refrigeration house.
Background
The frost formation of the bank pipe of the freezer evaporator can increase the flow resistance of air, and the frost layer is thickened to cause the reduction of heat transfer performance, so the defrosting is very important for the operation of the freezer evaporator.
The existing defrosting methods of the refrigeration house comprise electric heating defrosting, manual defrosting, hot air defrosting, water defrosting, compressed air defrosting and the like. The electric heating defrosting is simple and easy to implement, and is easy to realize automation, but the electric energy consumption is high. The influence of manual defrosting on the warehouse temperature is small, but the manual labor intensity is high, in addition, as the personnel need to warehouse in work, the working environment is poor, the heat generation of the personnel can increase the cold consumption amount, and the labor cost is also increased. The hot gas defrosting is energy-saving and has strong applicability, but the hot gas defrosting system is complex (a liquid drainage facility needs to be arranged). Water defrosting is generally combined with hot air defrosting, so that the operation is easy and the automation is realized, but the consumption of electric energy and water is high, and the cost is increased. The compressed air is used for defrosting by adopting a compressed air circulating type spraying evaporator surface, and micro frost on the evaporator surface is removed at any time, so that the evaporator surface is always kept in a frost-free state. Its advantage lies in guaranteeing refrigerating system's continuous operation to improve the daily output of device, but need compressed air, the defrosting process power consumption is more, and the device cost is higher.
The patent of 'a low-temperature defrosting structure of a-60 ℃ cold storage surface cooling type evaporator' (application number 201620072378.7) disclosed by Chinese patent No. CN205332642 comprises an evaporator main body, wherein the evaporator main body is arranged in a heat-insulating cavity isolated from a cold storage, one end of the heat-insulating cavity is provided with a refrigerating air outlet, the other end of the heat-insulating cavity is provided with a refrigerating air inlet, the refrigerating air outlet and the refrigerating air inlet are respectively provided with an electric shutter capable of being dynamically isolated from the cold storage, a defrosting spray device is arranged above the evaporator main body in the heat-insulating cavity and is connected with a defrosting liquid circulating conveying device, the side surface of the evaporator main body is provided with a circulating cooling fan, and a defrosting liquid outlet is arranged below the heat-insulating cavity; this patent is automatic closing electric shutter during defrosting, and the evaporimeter in the heat preservation cavity cuts off with the freezer, avoids the freezer interior storehouse temperature rise during the defrosting, and the inside intensification of evaporimeter leads to the influence that the freezer temperature rises during the defrosting that can greatly reduced can resources are saved, reduces running cost. When the defects are as follows: is affected by temperature and has large use limitation.
Chinese patent CN203940677 discloses "automatic defrosting system of freezer evaporator" patent (application number 201420329640.2), including the vapour and liquid separator, refrigeration compressor and at least one evaporator that connect gradually and form circulation circuit through the refrigerant pipeline, the evaporator subassembly is constituteed to the evaporator, is provided with directly to switch on between the head end department of evaporator subassembly and the vapour and liquid separator the reposition of redundant personnel pipeline of refrigeration compressor and vapour and liquid separator sets up high temperature hot gas pipeline between the evaporator of head end in refrigeration compressor and the evaporator subassembly. The patent has the advantages that: the system has a simple structure, can automatically defrost, has a quick defrosting mode, greatly reduces labor intensity, effectively reduces cost, saves energy and reduces emission. The defects are as follows: the defrosting time is longer, and the temperature of the warehouse is influenced to a certain extent.
Chinese patent CN105823293 discloses a "directional defrosting system of microwave of freezer evaporimeter calandria" patent (application number 201610386682.3), including motor, threaded rod, slider, through-hole, connecting rod, microwave generator, microwave pipe, metal reflection module, the cavity body, its characterized in that: a threaded rod is arranged on a rotating shaft of the motor; the central axis of the sliding block is provided with a through hole which is matched with the outer wall of the threaded rod, the sliding block is arranged on the outer wall of the threaded rod through the through hole, and the sliding block and the threaded rod are mechanically connected through threads; the lower end of the sliding block is fixedly connected with a microwave generator through a connecting rod; the microwave generators are communicated with the metal reflection module through the microwave guide pipe. The patent has the advantages that: reasonable in design, simple structure, convenient to use. The defects are as follows: when the frost layer is thin, microwave defrosting is still adopted, and energy waste is large.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: in order to overcome the defects of the prior art, the invention provides a technology based on the combination of microwave defrosting, physical defrosting and chemical defrosting, which avoids a large amount of manual labor, reduces the influence of labor cost and personnel warehousing on the cooling capacity consumption, avoids the influence of microwaves on the refrigerant in the evaporator calandria, and effectively improves the defrosting efficiency and the energy utilization rate.
The technical scheme adopted by the invention for solving the technical problems is as follows: a defrosting system for a refrigerator evaporator calandria is used for defrosting the evaporator calandria and comprises a PLC controller and a metal inner cover, wherein the metal inner cover is covered on the evaporator calandria, a metal outer cover is fixed outside the metal inner cover, at least one fan is fixed in the metal outer cover and arranged between the metal outer cover and the metal inner cover, the top of the metal inner cover is an openable structure which is connected with a PLC controller through a circuit and is controlled to be opened and closed by the PLC controller, and the position of the fan corresponding to the openable structure on the top of the metal inner cover is fixed; the pipeline on the inner metal cover is connected with a microwave catheter and is connected with a microwave generator through the microwave catheter; a defrosting device which is contacted with the upper surface of the evaporator calandria and is used for sweeping frost on the evaporator calandria is arranged in the metal inner cover corresponding to the upper part of the evaporator calandria, and drain pipes are respectively arranged at the bottom of the metal inner cover corresponding to the two sides of the evaporator calandria; the evaporator calandria top surface fixed with photoelectricity thickness sensor, photoelectricity thickness sensor and PLC controller line connection, PLC controller line connection has PLC working power supply.
The defrosting device comprises a fixed rod, a slidable rod, a defrosting brush and a motor, wherein the fixed rod is fixed with a metal inner cover, the slidable rod is connected to the lower end of the fixed rod in a sliding manner, the output end of the motor is fixed with the slidable rod and drives the slidable rod to reciprocate along the fixed rod, the defrosting brush is fixed on the lower surface of the slidable rod and is in contact with the upper surface of an evaporator tube bank, and the motor is connected with a PLC (programmable logic controller) through a circuit and is controlled by the PLC. The motor follows the action principle of the motor reciprocating circulation control circuit, so as to control the slidable rod to move back and forth, and the defrosting brush starts to sweep the frost on the surface of the evaporator discharge pipe back and forth as the defrosting brush is arranged on the slidable rod.
In addition, the frequency coverage of the microwave generator is between 300MHz and 300 GHz. The microwave catheter is a metal catheter with a circular cross section.
A defrosting method of a freezer evaporator calandria defrosting system adopts a mode of combining microwave defrosting, physical defrosting and chemical defrosting to defrost.
The method comprises the following defrosting steps:
step 1, starting a system, detecting the thickness of a frost layer on the surface of an evaporator calandria by a photoelectric thickness sensor, transmitting a frost layer thickness signal to a PLC (programmable logic controller), and if the thickness of the frost layer is 0, automatically closing the PLC control system and closing a defrosting system;
step 2, if the thickness of the frost layer is larger than 0, the PLC controls the frost sweeping device to start working, and the frost sweeping device retraces the frost on the surface of the evaporator calandria;
step 3, setting the interval time of the photoelectric thickness sensor to monitor the thickness of the frost layer, and judging whether the thickness of the frost layer is greater than a set value;
step 4, if the thickness of the frost layer is larger than a set value, the PLC controller controls the metal inner cover to be closed, the fan to be closed and the microwave generator to operate, microwaves are transmitted into the metal cover through the microwave guide pipe, heat is uniformly reflected in the metal inner cover, the frost layer on the surface of the evaporator calandria is melted, and microwave heating defrosting is carried out;
step 5, if the thickness of the frost layer is not more than a set value, the PLC controller controls the metal inner cover to be opened, the fan to be opened, the microwave generator to stop operating and the fan to be started, and the frost on the surface of the evaporator pipe bank is blown, namely, the blowing defrosting is carried out while the frost sweeping device works;
step 6, when the sweeping and defrosting device works and simultaneously sweeps and defrosts, the photoelectric thickness sensor continues to monitor the thickness of the frost layer, and the steps 1 to 5 are repeatedly executed until the thickness of the frost layer is 0, and the system is closed;
further, the interval time for which the photoelectric thickness sensor monitors the thickness of the frost layer in step 3 is set to 20 minutes.
According to the invention, through the cooperation of the PLC and the photoelectric thickness sensor, in the defrosting process, the defrosting is selectively performed by blowing or microwave heating according to the thickness of a frost layer, three defrosting methods of physical defrosting, chemical defrosting and microwave defrosting are integrated, the defrosting efficiency is effectively improved, and the energy-saving requirement is met. The physical defrosting mainly sweeps away the frost layer on the surface by controlling the movement of the defrosting brush through the motor, and compared with manual defrosting, a large amount of manual labor is avoided, so that the influence of labor cost and personnel warehousing on the cooling capacity is reduced. The defrosting mode combining physical defrosting and chemical defrosting mainly blows off the loosened frost on the surface of the evaporator discharge pipe after the defrosting brush is swept by the fan, and simultaneously melts partial frost due to the influence of wind temperature. The microwave defrosting mainly comprises the steps that a frost layer is melted after absorbing energy released by microwaves, and in addition, the influence of the microwaves on a refrigerant in an evaporator pipe bank is avoided by utilizing the characteristics that the microwaves cannot penetrate through metal and can be reflected on the surface of the metal, so that the efficient defrosting is realized. The defrosting and the microwave defrosting are selectively carried out through the cooperation of the photoelectric thickness sensor and the PLC according to the thickness of a frost layer, so that the energy utilization rate is improved, and compared with the traditional electric heating defrosting, manual defrosting and hot air defrosting, the energy-saving and efficient defrosting device is more energy-saving and efficient.
The defrosting system and the defrosting method for the evaporator calandria of the refrigeration house, provided by the invention, have the beneficial effects that based on the technology of combining microwave defrosting, physical defrosting and chemical defrosting, a large amount of manual labor is avoided, the influence of labor cost and personnel warehousing on the cooling capacity consumption is reduced, the influence of microwaves on the refrigerant in the evaporator calandria is avoided, and the defrosting efficiency and the energy utilization rate are effectively improved.
Drawings
The invention is further illustrated with reference to the following figures and examples.
Fig. 1 is a front view of the preferred embodiment of the present invention.
Figure 2 is a side view of the preferred embodiment of the present invention.
Fig. 3 is a top view of the preferred embodiment of the present invention.
Fig. 4 is a schematic diagram of the electro-optical thickness sensor of the preferred embodiment of the present invention on the evaporator gauntlet.
FIG. 5 is a flow chart of the preferred embodiment of the present invention in which the PLC controls defrost.
Fig. 6 is a top view of the inner metal cover in the preferred embodiment of the invention.
Fig. 7 is a left side view at the inner metal cover.
Fig. 8 is a front view at the inner metal cover.
Fig. 9 is a schematic structural diagram of the connection part of the semicircular cover body and the fixed connection unit in the preferred embodiment of the invention.
In the figure 1, a microwave generator 2, a microwave guide tube 3, a fan 4, a fixed rod 5, a metal outer cover 6, a metal inner cover 7, a defrosting brush 8, a slidable rod 9, a microwave radiation area 10, a motor 11, a PLC (programmable logic controller) 12, a photoelectric thickness sensor 13, a drain pipe 14, a fixed connection unit 15, an evaporator discharge pipe 16 and a control system switch.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.
The freezer evaporator bank pipe defrosting system as shown in fig. 1 to 4 is the most preferred embodiment of the present invention, and is used for defrosting the evaporator bank pipe 15. The defrosting system comprises a PLC (programmable logic controller) 11 and further comprises an outer cover 6 arranged in an evaporator pipe 15, a photoelectric thickness sensor 12 is fixed on the surface of the top end of the evaporator pipe 15, the photoelectric thickness sensor 12 is connected with 11 lines of the PLC, and a PLC working power supply is connected with the lines of the PLC. The PLC working power supply is a 220V power supply. A frost sweeping device which is in contact with the upper surface of the evaporator calandria 15 and sweeps frost on the evaporator calandria 15 is arranged in the metal inner cover 6 and above the evaporator calandria 15. The PLC 11 is preferably SIMATIC S7-300 series PLC, and the temperature of the cold storage is generally-20 deg.C-5 deg.C, so that SIMATIC S7-300 with extended environmental conditions is selected, and the working environment temperature is-25 deg.C-60 deg.C. The PLC controller 11 is controlled to be turned on and off by a control system switch 16.
The frost sweeping device comprises: a fixed lever 4, a slidable lever 8, a defrost brush 7, and a motor 10. The fixed rod 4 is fixed with the metal inner cover 6, and 8 sliding connections of slidable rod are at the 4 lower extremes of fixed rod, the output of motor 10 is fixed with slidable rod 8 and drives slidable rod 8 along 4 reciprocating motion of fixed rod, and defrosting brush 7 then is fixed at 8 lower surfaces of slidable rod and with 15 upper surface contact in evaporimeter calandria, motor 10 and 11 line connection of PLC controller and by PLC controller 11 control. The motor 10 follows the operation principle of the motor 10 reciprocating control circuit to control the slidable rod 8 to move back and forth, and since the defrosting brush 7 is on the slidable rod 8, the defrosting brush 7 starts to sweep back the frost on the surface of the evaporator discharge tube 15. Since the motor 10 is installed in a refrigerator, in actual assembly, the motor 10 having a function of preventing the entry of solid particles larger than 1mm and preventing splash water is preferable.
The upper pipeline of the inner metal cover 6 is connected with a microwave guide pipe 2 and is connected with a microwave generator 1 through the microwave guide pipe 2; the frequency of coverage of the microwave generator 1 is between 300MHz and 300 GHz. The microwave catheter 2 is a metal catheter having a circular cross section. The bottom of the inner metal cover 6 is provided with drain pipes 13 corresponding to the two sides of the evaporator discharge pipe 15, and water generated by defrosting and melting can be discharged through the drain pipes 13.
The metal outer cover 5 is fixed outside the metal inner cover 6, and the four fans 3 arranged between the metal outer cover 5 and the metal inner cover 6 are fixed inside the metal outer cover 5. The top of the inner metal cover 6 is an openable structure which is connected with a PLC (programmable logic controller) 11 through a circuit and is controlled to be opened and closed by the PLC 11, and the position of the fan 3 corresponding to the openable structure at the top of the inner metal cover 6 is fixed. The inner metal cover 6 and the outer metal cover 5 are made of conductive metal, and because the metal reflects microwave and does not absorb microwave energy, the inner area of the inner metal cover 6 is hollow, namely a microwave radiation area 9. In operation, the microwave processor generates microwave, the microwave is transmitted to the microwave radiation area 9 through the microwave guide pipe 2, the microwave continuously and uniformly reflects heat in the metal inner cover 6, so that the microwave acts on a frost layer in a large area in the metal space, and frost is melted by the heat of the microwave.
In practical design, the opening of the inner metal cover 5 can be realized by a method that the PLC 11 controls the rotation of the semicircular cover body. As shown in fig. 6 to 9, the inner metal cover 5 is composed of two semicircular covers, and rectangular fixed connection units 14 are respectively provided at both ends tangent to the two semicircular covers. When the inner metal cover 5 receives an opening signal, both the semicircular covers rotate by 95 ° downward with the fixed connection unit 14 as an axis. At this point the fan 3 is turned on and the PLC controller 11 transmits a shutdown signal to the microwave processor, which is not operating. When the metal inner cover 5 receives a closing signal, the two semicircular cover bodies rotate upwards by taking the fixed connection unit 14 as an axis, the two semicircular cover bodies are restored to be in a closed state, the PLC 11 transmits an opening signal to the microwave processor, and the microwave processor operates.
In the above structure, three defrosting structures of microwave defrosting, physical defrosting and chemical defrosting are integrated. Physical defrost is mainly by means of a motor 10 controlling the movement of the defrost brush 7 to sweep the frost layer of the surface. The defrosting mode combining physical defrosting and chemical defrosting is mainly that the fan 3 blows off the loosened frost on the surface of the evaporator discharge pipe 15 after the defrosting brush 7 sweeps, and meanwhile, partial frost is melted due to the influence of wind temperature. When the frost layer is thicker or harder, the microwave processor generates microwave, the microwave is transmitted to the microwave radiation area 9 through the microwave guide pipe 2, the microwave defrosting enables the microwave to act on the frost layer in a large area in the metal space through metal reflection, and the heat of the microwave is utilized to defrost and defrost efficiently.
The defrosting method of the defrosting system with the structure combines microwave defrosting, physical defrosting and chemical defrosting, and comprises the following defrosting steps:
step 1, starting a system, wherein a photoelectric thickness sensor 12 detects the thickness of a frost layer on the surface of an evaporator calandria 15 and transmits a frost layer thickness signal to a PLC (programmable logic controller) 11, and if the thickness of the frost layer is 0, the PLC 11 controls the system to be automatically closed and a defrosting system to be closed;
step 2, if the thickness of the frost layer is larger than 0, the PLC 11 controls the frost sweeping device to start working, and the frost sweeping device retraces the frost on the surface of the evaporator calandria 15;
step 3, setting 12 intervals of the photoelectric thickness sensor to monitor the thickness of the frost layer, and judging whether the thickness of the frost layer is larger than a set value;
step 4, if the thickness of the frost layer is larger than a set value, the PLC 11 controls the metal inner cover 6 to be closed, the fan 3 to be closed and the microwave generator 1 to operate, microwaves are transmitted into the metal cover through the microwave guide pipe 2, heat is uniformly reflected in the metal inner cover 6, the frost layer on the surface of the evaporator calandria 15 is melted, and microwave heating defrosting is carried out;
step 5, if the thickness of the frost layer is not more than a set value, the PLC 11 controls the metal inner cover 6 to be opened, the fan 3 to be opened, the microwave generator 1 to stop operating and the fan 3 to be started, and the frost on the surface of the evaporator exhaust pipe 15 is blown, namely, the blowing defrosting is carried out while the defrosting device works;
step 6, when the sweeping defrosting device works and simultaneously performs sweeping defrosting, the photoelectric thickness sensor 12 continues to monitor the thickness of the frost layer, and the steps 1 to 5 are repeatedly executed until the thickness of the frost layer is 0, and the system is closed;
during this defrosting, the frost thickness set value may preferably be set to 10mm, and the interval between monitoring of the frost thickness by the photoelectric thickness sensor 12 in step 3 is set to 20 minutes.
In the invention, through the cooperation of the PLC 11 and the photoelectric thickness sensor 12, in the defrosting process, the defrosting is selectively carried out by blowing or microwave heating according to the thickness of a frost layer, and three defrosting methods of physical defrosting, chemical defrosting and microwave defrosting are integrated into a whole, thereby effectively improving the defrosting efficiency and meeting the energy-saving requirement. The physical defrosting mainly controls the movement of the defrosting brush 7 through the motor 10 to sweep away the frost layer on the surface, and compared with manual defrosting, a large amount of manual labor is avoided, so that the influence of labor cost and personnel warehousing on the cooling capacity is reduced. The defrosting mode combining physical defrosting and chemical defrosting mainly blows off the loosened frost on the surface of the evaporator discharge pipe 15 after the defrosting brush 7 is swept by the fan 3, and simultaneously melts part of the frost due to the influence of wind temperature. The microwave defrosting mainly comprises the steps that a frost layer is melted after absorbing energy released by microwaves, and in addition, the influence of the microwaves on a refrigerant in an evaporator discharge pipe 15 is avoided by utilizing the characteristics that the microwaves cannot penetrate through metal and can be reflected on the surface of the metal, so that efficient defrosting is realized. The defrosting and the microwave defrosting are selectively carried out through the cooperation of the photoelectric thickness sensor 12 and the PLC 11 according to the thickness of a frost layer, so that the energy utilization rate is improved, and compared with the traditional electric heating defrosting, manual defrosting and hot air defrosting, the energy-saving and efficient defrosting device is more energy-saving and efficient.
The freezer evaporator calandria defrosting system designed by the invention is based on the technology of combining microwave defrosting, physical defrosting and chemical defrosting, avoids a large amount of manual labor, reduces the influence of labor cost and personnel warehousing on the cooling capacity consumption, avoids the influence of microwaves on the refrigerant in the evaporator calandria 15, and effectively improves the defrosting efficiency and the energy utilization rate.
In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims (6)

1. The utility model provides a freezer evaporimeter calandria defrost system for carry out the defrosting operation to the evaporimeter calandria, its characterized in that: the evaporator comprises a PLC controller and a metal inner cover, wherein the metal inner cover is externally covered on an evaporator tube bank and is externally fixed with a metal outer cover; the pipeline on the inner metal cover is connected with a microwave catheter and is connected with a microwave generator through the microwave catheter; a defrosting device which is contacted with the upper surface of the evaporator calandria and is used for sweeping frost on the evaporator calandria is arranged in the metal inner cover corresponding to the upper part of the evaporator calandria, and drain pipes are respectively arranged at the bottom of the metal inner cover corresponding to the two sides of the evaporator calandria; the evaporator calandria top surface fixed with photoelectricity thickness sensor, photoelectricity thickness sensor and PLC controller line connection, PLC controller line connection has PLC working power supply.
2. The freezer evaporator calandria defrost system of claim 1, characterized in that: the defrosting device comprises a fixed rod, a slidable rod, a defrosting brush and a motor, the fixed rod is fixed with the metal inner cover, the slidable rod is connected to the lower end of the fixed rod in a sliding mode, the output end of the motor is fixed with the slidable rod and drives the slidable rod to reciprocate along the fixed rod, the defrosting brush is fixed to the lower surface of the slidable rod and contacts with the upper surface of an evaporator tube bank, and the motor is connected with a PLC (programmable logic controller) and is controlled by the PLC.
3. The freezer evaporator calandria defrost system of claim 1, characterized in that: the covering frequency of the microwave generator is between 300MHz and 300 GHz.
4. The freezer evaporator calandria defrost system of claim 1, characterized in that: the microwave catheter is a metal catheter with a circular section.
5. The defrosting method of the refrigerator evaporator calandria defrosting system is characterized in that: the method for defrosting by adopting a mode of combining microwave defrosting, physical defrosting and chemical defrosting comprises the following defrosting steps:
step 1, starting a system, detecting the thickness of a frost layer on the surface of an evaporator calandria by a photoelectric thickness sensor, transmitting a frost layer thickness signal to a PLC (programmable logic controller), and if the thickness of the frost layer is 0, automatically closing the PLC control system and closing a defrosting system;
step 2, if the thickness of the frost layer is larger than 0, the PLC controls the frost sweeping device to start working, and the frost sweeping device retraces the frost on the surface of the evaporator calandria;
step 3, setting the interval time of the photoelectric thickness sensor to monitor the thickness of the frost layer, and judging whether the thickness of the frost layer is greater than a set value;
step 4, if the thickness of the frost layer is larger than a set value, the PLC controller controls the metal inner cover to be closed, the fan to be closed and the microwave generator to operate, microwaves are transmitted into the metal cover through the microwave guide pipe, heat is uniformly reflected in the metal inner cover, the frost layer on the surface of the evaporator calandria is melted, and microwave heating defrosting is carried out;
step 5, if the thickness of the frost layer is not more than a set value, the PLC controller controls the metal inner cover to be opened, the fan to be opened, the microwave generator to stop operating and the fan to be started, and the frost on the surface of the evaporator pipe bank is blown, namely, the blowing defrosting is carried out while the frost sweeping device works;
and 6, when the sweeping and defrosting device works and simultaneously sweeps and defrosts, the photoelectric thickness sensor continuously monitors the thickness of the frost layer, and the steps 1 to 5 are repeatedly executed until the thickness of the frost layer is 0, and the system is closed.
6. The defrosting method of a freezer evaporator calandria defrosting system of claim 5 which is characterized by the following: the interval time for monitoring the thickness of the frost layer by the photoelectric thickness sensor in the step 3 is set to be 20 minutes.
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CN109631441A (en) * 2019-01-25 2019-04-16 中国建筑科学研究院有限公司 Method and device for efficiently melting cold surface frost layer
CN112665273A (en) * 2021-01-21 2021-04-16 上海工程技术大学 Air-cooled refrigerator capable of defrosting by microwave
CN113418333B (en) * 2021-07-03 2022-03-01 苏州咖鲜生智能科技有限公司 Milk fresh-keeping freezer

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