An intelligent defrost controller based on diffuse reflection photoelectric conversion
By using a diffuse reflection photoelectric conversion controller in the cold storage, the frost layer thickness is accurately detected and the defrost process is controlled, which solves the problem of poor defrost effect in the prior art, and improves the refrigeration performance and energy-saving effect of the cold storage.
Patent Information
- Application Number
- CN202111420395.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-11-26
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2041-11-26
AI Technical Summary
The existing cold storage defrosting methods cannot accurately determine the melting point, which affects the defrosting effect and system efficiency, resulting in a decrease in the cooling capacity and performance coefficient COP, and the frost layer hinders the airflow and increases fan energy consumption.
Using intelligent frost controller based on diffuse photoelectric conversion, the first and second diffuse photoelectric sensors, temperature sensors and heating resistors, combined with timers and switches, accurately detect and control the thickness of the frost layer, and remove as needed. frost to reduce energy waste.
Accurate detection and control of the thickness of the frost layer of the cold storage evaporator is achieved, unnecessary defrost is reduced, system efficiency is improved, energy consumption is reduced, and refrigeration performance is improved.
Smart Images
Figure CN114111179B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of intelligent defrosting of cold storage air coolers, and in particular provides a defrosting system and method based on diffuse reflection photoelectric conversion control. Background Art
[0002] Low temperature and high humidity refrigeration is conducive to the preservation of agricultural products. The storage temperature is generally slightly higher than the freezing point of the product, and the storage humidity is generally above 90%. However, in this case, once the surface temperature of the evaporator of the cold storage refrigeration system is lower than the freezing point of water and the dew point of the air, it is easy to frost. The initial frosting of the evaporator is favorable because the frosting reduces the contact resistance of the finned tubes, and the rough frosted surface plays the role of the fins, but as the frosting thickness increases, the frosting insulation effect prevails, and the cooling capacity of the cold storage evaporator decreases. When the refrigeration system operates under frosting conditions, the cooling capacity and performance coefficient COP are reduced by 20-30%. In addition, the frost layer hinders the airflow through the evaporator, resulting in an increase in the pressure drop on the air side and an increase in the fan energy consumption. Therefore, timely and effective defrosting of the evaporator is of great significance to the energy-saving operation of the cold storage.
[0003] At present, the defrosting methods used in cold storage include manual defrosting, electric heating defrosting, hot air defrosting, water defrosting, reversing defrosting, liquid refrigerant defrosting, etc. The existing defrosting methods have a common problem: the melting point cannot be accurately determined, which affects the defrosting effect and then affects the system efficiency.
[0004] The present invention proposes an intelligent defrost controller based on diffuse reflection photoelectric conversion, which uses a diffuse reflection photoelectric sensor to sense the thickness of the frost layer and accurately determine the defrost point, thereby reducing the influence of the frost layer on the heat exchange effect and improving the system efficiency. Summary of the invention
[0005] The object of the present invention is to provide a control method for defrosting on demand, and to provide a defrosting system and method for a cold storage air cooler based on diffuse reflection photoelectric conversion control. The defrosting system comprises a first diffuse reflection photoelectric sensor (1), a second diffuse reflection photoelectric sensor (2), a temperature sensor (3), a heating resistor (6) and a defrost controller, wherein a power supply 7, a defrost start switch K1, a timer (8), a switch K2, a defrost stop switch K3 and a switch K4 are installed in the defrost controller, wherein the timer (8) and the switch K2 are connected to form an instantaneous closing and delay opening switch, and the temperature sensor (3) and the switch K4 are connected to form a stable defrost switch.
[0006] The technical solution of the present invention is as follows:
[0007] According to claim 1, a diffuse reflection photoelectric conversion intelligent defrost controller is characterized in that the timer (8) is set to 20 to 300 minutes. The specific operation of the timer (8) is as follows: according to the first defrost stop mode, first, the first diffuse reflection photoelectric sensor (1) detects that the frost layer thickness is less than a value (such as 8 mm). At this time, a manual timing method is used to obtain the time taken for the frost layer thickness to change from 8 mm to the frost layer melting and the defrosting water not being retained on the evaporator surface. Experiment n groups and take the average value. The average value is the time preset by the timer (8).
[0008] Defrost start: When the air in the cold storage encounters the evaporator surface below 0°C, the water vapor in the air precipitates and forms solid frost crystals. Frosting begins when the temperature sensor (3) measures that the evaporator surface temperature is below 0°C, and the switch K4 is closed. When the thickness of the frost layer (5) is higher than the sensing surface of the second diffuse reflection photoelectric sensor, the defrost stop switch K3 is closed. When the thickness of the frost layer (5) is higher than the sensing surface of the first diffuse reflection photoelectric sensor, the surface of the air cooler is already covered with frost and needs to be defrosted immediately. The switches K1 and K2 are closed, the heating resistor (6) is energized, and the defrosting begins.
[0009] There are two situations when defrost stops:
[0010] The first defrosting stop mode: when the thickness of the frost layer (5) is lower than the sensing surface of the first diffuse reflection photoelectric sensor, the switch K1 is disconnected, and the timer (8) starts timing. When the time is up, the switch K2 is disconnected, the heating resistor (6) is powered off, and the defrosting stops.
[0011] The second defrosting stop mode: when the thickness of the frost layer (5) is lower than the sensing surface of the first diffuse reflection photoelectric sensor, the switch K1 is disconnected, and the thickness of the frost layer (5) continues to decrease; when the thickness of the frost layer (5) is lower than the sensing surface of the second diffuse reflection photoelectric sensor, the switch K3 is disconnected, the heating resistor (6) is powered off, and the defrosting stops.
[0012] The beneficial effects of the present invention are as follows: the defrost controller can directly detect the thickness of frost on the surface of the air cooler, and can achieve on-demand defrosting, thus avoiding unnecessary defrosting. Through the diffuse reflection photoelectric converter, when the frost layer accumulates to a certain thickness, the photoelectric switch generates a switch signal to determine the defrosting entry point and defrosting exit point, thereby reducing energy waste and achieving energy saving in the cold storage. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 It is a schematic diagram of an intelligent defrost controller based on diffuse reflection photoelectric conversion;
[0014] Figure 2 This is an internal operating circuit diagram of an intelligent defrost controller based on diffuse reflection photoelectric conversion.
[0015] In the figure: 1. first diffuse reflection photoelectric sensor, 2. second diffuse reflection photoelectric sensor, 3. temperature sensor, 4. heat exchanger surface, 5. frost layer, 6. heating resistor, 7. power supply, 8. timer. DETAILED DESCRIPTION
[0016] The principle of the present invention is further described below with reference to the accompanying drawings and examples. It should be noted that the present examples are descriptive rather than restrictive, and the protection scope of the present invention is not limited thereto.
[0017] Example 1 takes a complete frosting and defrosting cycle as an example and operates in the first defrosting stop mode. When the air in the cold storage encounters the evaporator surface below 0°C, the water vapor in the air precipitates and forms solid frost crystals, and frosting begins. When the temperature sensor (3) measures that the evaporator surface temperature is below 0°C, the switch K4 is closed. When the thickness of the frost layer (5) is higher than the sensing surface of the second diffuse reflection photoelectric sensor, the switch K3 is closed. When the thickness of the frost layer (5) is higher than the sensing surface of the first diffuse reflection photoelectric sensor, the surface of the air cooler is already covered with frost and needs to be defrosted immediately. The switches K1 and K2 are closed, the heating resistor (6) is powered on, and defrosting begins. After the frost layer absorbs heat, the thickness of the frost layer decreases. When the thickness of the frost layer (5) is lower than the sensing surface of the first diffuse reflection photoelectric sensor, the switch K1 is disconnected, the timer (8) starts timing, and when the time is up, the switch K2 is disconnected, the heating resistor (6) is powered off, and defrosting stops. The refrigeration unit enters the next frosting and defrosting cycle.
[0018] Example 2 takes a complete frosting and defrosting cycle as an example and operates in the second defrosting stop mode. When the air in the cold storage encounters the evaporator surface below 0°C, the water vapor in the air precipitates and forms solid frost crystals, and frosting begins. When the temperature sensor (3) measures that the evaporator surface temperature is below 0°C, the switch K4 is closed. When the thickness of the frost layer (5) is higher than the second diffuse reflection photoelectric sensor sensing surface, the switch K3 is closed. When the thickness of the frost layer (5) is higher than the first diffuse reflection photoelectric sensor sensing surface, the surface of the air cooler is already covered with frost and needs to be defrosted immediately. The switches K1 and K2 are closed, the heating resistor (6) is powered on, and defrosting begins. After the frost layer absorbs heat, the thickness of the frost layer decreases. When the thickness of the frost layer (5) is lower than the first diffuse reflection photoelectric sensor sensing surface, the switch K1 is disconnected, and the thickness of the frost layer (5) continues to decrease. When the thickness of the frost layer (5) is lower than the second diffuse reflection photoelectric sensor sensing surface, the switch K3 is disconnected, the heating resistor (6) is powered off, and defrosting stops. The refrigeration unit enters the next frosting and defrosting cycle.
[0019] Matters not covered by the present invention are known technologies.
[0020] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.
Claims
1. An intelligent defrost controller based on diffuse reflection photoelectric conversion, characterized in that: The device comprises a first diffuse reflection photoelectric sensor (1), a second diffuse reflection photoelectric sensor (2), a temperature sensor (3), a heating resistor (6) and a defrost controller, wherein the defrost controller control circuit comprises a power supply (7), a switch K2, a switch K3, a switch K4, a heating resistor (6), a switch K1 and a timer (8); the power supply (7), the switch K2, the switch K3, the switch K4 and the heating resistor (6) are sequentially connected to form a series circuit, the switch K1 and the timer (8) are connected in series, and the series circuit formed by the power supply (7), the switch K1 and the timer (8) is connected in parallel; The defrost controller has two states: defrost start and defrost stop: Defrost start: when the temperature measured by the temperature sensor (3) is lower than 0°C, the switch K4 is closed; when the thickness of the frost layer (5) is higher than the sensing surface of the second diffuse reflection photoelectric sensor (2), the defrost stop switch K3 is closed; when the thickness of the frost layer (5) is higher than the sensing surface of the first diffuse reflection photoelectric sensor (1), the switches K1 and K2 are closed, the heating resistor (6) is energized, and defrosting starts; There are two situations when defrost stops: The first defrosting stop mode: when the thickness of the frost layer (5) is lower than the sensing surface of the first diffuse reflection photoelectric sensor (1), the switch K1 is disconnected, and the timer (8) starts timing. When the time is up, the switch K2 is disconnected, the heating resistor (6) is powered off, and the defrosting stops. The second defrosting stop mode: when the thickness of the frost layer (5) is lower than the sensing surface of the first diffuse reflection photoelectric sensor (1), the switch K1 is disconnected, the timer (8) starts timing, and the thickness of the frost layer (5) continues to decrease. When the thickness of the frost layer (5) is lower than the sensing surface of the second diffuse reflection photoelectric sensor (2), the switch K3 is disconnected, the heating resistor (6) is powered off, and the defrosting stops.
2. The intelligent defrost controller based on diffuse reflection photoelectric conversion according to claim 1, characterized in that: The timer (8) is set to a time range of 20 to 300 minutes.
3. The intelligent defrost controller based on diffuse reflection photoelectric conversion according to claim 1, characterized in that: The heating resistor (6) is installed on the surface of the heat exchanger.
4. The intelligent defrost controller based on diffuse reflection photoelectric conversion according to claim 1, characterized in that: The temperature sensor (3) is installed on the surface of the heat exchanger.
5. The intelligent defrost controller based on diffuse reflection photoelectric conversion according to claim 1, characterized in that: The sensing surface of the first diffuse reflection photoelectric sensor (1) is 5 to 15 mm higher than the surface of the heat exchanger, and the sensing surface of the second diffuse reflection photoelectric sensor (2) is 0.2 to 1 mm higher than the surface of the heat exchanger. The sensing sensitivities of the first diffuse reflection photoelectric sensor and the second diffuse reflection photoelectric sensor can be adjusted.