CN216048472U - Thermoelectric refrigerating system and refrigerating equipment - Google Patents

Abstract

The utility model discloses a thermoelectric refrigerating system and refrigerating equipment, wherein the thermoelectric refrigerating system comprises a direct-current power supply, a semiconductor circuit connected with the direct-current power supply and switch circuits connected to two ends of the direct-current power supply, and the switch circuits are used for changing the current flow direction in the semiconductor circuit so as to switch the semiconductor circuit to be in a refrigerating mode or an energy storage mode. Compared with the prior art, the thermoelectric refrigeration system capable of supplementing the refrigeration house equipment can store electric energy when the refrigeration house equipment is normally powered on, can perform auxiliary refrigeration when a power grid fails, and ensures that the temperature in the refrigeration house can be kept stable.

Description

Thermoelectric refrigerating system and refrigerating equipment

Technical Field

The utility model relates to the field of refrigeration, in particular to a thermoelectric refrigeration system and refrigeration equipment.

Background

Along with the continuous popularization of refrigeration technology, frozen and refrigerated products are used in various industries, the refrigerated products sold in the current market generally comprise an air cooler, a condenser, a refrigerator car, a refrigerator and the like, a small part of units are matched for use, and the requirements of a user on storing agricultural products such as food, fruits and vegetables and meat can be met through evaporation and heat exchange of the air cooler. The complete set of refrigeration equipment is generally supplied with power by a high-power grid, but the power failure condition can occur when the load of the power grid is overlarge, so that the refrigeration effect of a refrigeration house cannot be ensured when the condition occurs, and an additional system is needed to ensure the power supply of the refrigeration house in areas with unstable power grids, thereby ensuring the quality of stored goods.

Therefore, how to design a thermoelectric refrigeration system and a refrigeration device capable of maintaining a stable temperature in a refrigerator is an urgent technical problem to be solved in the industry.

SUMMERY OF THE UTILITY MODEL

The utility model provides a thermoelectric refrigerating system and refrigerating equipment, aiming at the problem that the refrigerating effect of a refrigeration house is influenced by the power failure of a power grid in the prior art.

The thermoelectric refrigeration system comprises a direct-current power supply, a semiconductor circuit connected with the direct-current power supply, and switch circuits connected to two ends of the direct-current power supply, wherein the switch circuits are used for changing the current flow direction in the semiconductor circuit, so that the semiconductor circuit is switched to be in a refrigeration mode or an energy storage mode.

Further, the semiconductor circuit comprises a first metal plate used for forming a cold end, a second metal plate and a third metal plate used for forming a hot end, a P-type semiconductor connected between the first metal plate and the second metal plate, and an N-type semiconductor connected between the first metal plate and the third metal plate, wherein two poles of the direct-current power supply are respectively connected with the second metal plate and the third metal plate.

Further, when the direct current power supply supplies power, the current carriers at the P-type semiconductor flow from the first metal plate to the second metal plate, the current carriers at the N-type semiconductor flow from the first metal plate to the third metal plate, the current carriers absorb heat when flowing from the first metal plate to the P-type semiconductor and the N-type semiconductor, so that the first metal plate forms a cold end, the current carriers release heat when flowing from the P-type semiconductor and the N-type semiconductor to the second metal plate and the third metal plate, so that the second metal plate and the third metal plate form a hot end.

Further, the refrigerating capacity of the cold end is as follows: phi 0= alpha · I · Tc-K · Δ T-1/2 · I · R;

wherein, alpha is the thermoelectric power factor, I is the current of the semiconductor circuit, Tc is the temperature of the cold junction, K is the thermal conductance of the semiconductor, DeltaT is the heat absorbed or released by the metal plate, and R is the resistance of the whole loop of the thermoelectric refrigerating circuit.

Further, the direct current power supply is a chargeable direct current power supply, and when the temperature difference exists between the first metal plate and the second metal plate and between the first metal plate and the third metal plate, the semiconductor circuit charges the direct current power supply.

Further, when the switching circuit is switched to enable the current carriers to flow out of the first metal plate, the semiconductor circuit works in a refrigeration mode and refrigerates through the cold end;

when the switching circuit is switched to enable the current carriers to flow to the first metal plate, the semiconductor circuit works in an energy storage mode and supplies power to the direct-current power supply through the temperature difference electromotive force.

Further, the switch circuit comprises a switch S1, a switch S2, a switch S3 and a switch S4, wherein one end of the switch S1 is connected to the second metal plate, the other end of the switch S1 is connected to the third metal plate after being connected in series with the switch S2, one end of the switch S3 is connected to the second metal plate, the other end of the switch S4 is connected to the fourth metal plate after being connected in series with the switch S4, the positive pole of the direct-current power supply is connected between the switch S1 and the switch S2, and the negative pole of the direct-current power supply is connected between the switch S3 and the switch S4;

when the switch S2 and the switch S3 are closed, the semiconductor circuit operates in a cooling mode;

when the switch S1 and the switch S4 are closed, the semiconductor circuit operates in a tank mode.

When the semiconductor circuit works in a refrigerating mode, the thermistor controls the current in the semiconductor circuit so as to control the refrigerating capacity.

Further, the maximum current of the semiconductor circuit is: imax = α · Tc/R;

wherein, alpha is the thermoelectric power factor, Tc is the temperature of the cold junction, and R is the resistance of the whole loop of the thermoelectric refrigeration circuit.

The utility model also provides a refrigerating device which adopts the thermoelectric refrigerating system.

Further, the refrigeration equipment is any one of an air cooler, a condenser, a refrigerator car and a refrigerator.

Compared with the prior art, the utility model has at least the following beneficial effects:

1. through the arrangement of the semiconductor circuit, auxiliary refrigeration can be carried out when a power grid fails, and the temperature in the refrigerator is kept stable.

2. When the refrigeration house normally works, the direct-current power supply can be powered by electromotive force generated by temperature difference between the metal plates, and the energy storage effect is achieved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

FIG. 1 is a schematic diagram of a thermoelectric refrigeration system of the present invention;

FIG. 2 is a cross-sectional schematic view of a uniform internal heat source.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not intended to limit the utility model.

Thus, a feature indicated in this specification will serve to explain one of the features of one embodiment of the utility model, and does not imply that every embodiment of the utility model must have the stated feature. Further, it should be noted that this specification describes many features. Although some features may be combined to show a possible system design, these features may also be used in other combinations not explicitly described. Thus, the combinations illustrated are not intended to be limiting unless otherwise specified.

The principles and construction of the present invention will be described in detail below with reference to the drawings and examples.

In the prior art, when a power grid fails, the refrigeration effect of a refrigeration house cannot be guaranteed, so that the quality of goods is influenced. The idea of the present invention is to provide a thermoelectric refrigeration system which is complementary to a refrigerator and can perform auxiliary refrigeration when a power grid fails, thereby maintaining the temperature in the refrigerator.

The thermoelectric refrigerating system comprises a direct-current power supply and a semiconductor circuit connected with the direct-current power supply, wherein the semiconductor circuit comprises at least one semiconductor and metal plates connected to two ends of the semiconductor and used for forming a cold end and a hot end, and refrigeration is carried out through the cold end.

The basic working principle is that as the potential energy of the current carrier in the semiconductor is higher than that in the metal, when the DC power supply supplies power to the semiconductor circuit, the current carrier moves along with the current to flow from the metal plate to the semiconductor, and at the moment, as the potential energy is increased, the current carrier absorbs heat, so that the temperature on the metal plate is reduced, and the refrigeration effect is achieved. The semiconductor is divided into an N-type semiconductor and a P-type semiconductor, holes are filled in the N-type semiconductor, the flowing direction of the holes is the same as the current direction, electrons are filled in the P-type semiconductor, the flowing direction of the electrons is opposite to the current direction, and the flowing direction of carriers (including the holes and the electrons) is adjusted by controlling the flowing direction of the current, so that the refrigerating effect is achieved.

Referring to fig. 1, the semiconductor circuit includes a first metal plate, a second metal plate and a third metal plate, wherein the first metal plate is used to form a cold end, the second metal plate and the third metal plate are used to form a hot end, a P-type semiconductor is connected between the first metal plate and the second metal plate, an N-type semiconductor is connected between the first metal plate and the third metal plate, and two poles of a dc power supply are respectively connected to the second metal plate and the third metal plate.

When the positive electrode of the direct current power supply is connected to the third metal plate for supplying power, the current flows anticlockwise, electrons on the N-type semiconductor flow from the negative electrode to the positive electrode under the action of an external electric field, and holes in the P-type semiconductor flow from the positive electrode to the negative electrode. When electrons flow from the first metal plate to the N-type semiconductor, heat is absorbed to lower the temperature of the first metal plate due to the increase of potential energy, and similarly, heat is absorbed to lower the temperature of the first metal plate when holes flow from the first metal plate to the P-type semiconductor, thereby forming a cold end. When electrons flow from the N-type semiconductor to the third metal plate, heat needs to be released due to potential energy reduction, the temperature of the third metal plate is increased, and the hot end is formed.

According to thermoelectric effect, can distribute first metal sheet in the refrigeration space, if in the freezer space, then can place the metal sheet wall to reach the refrigeration effect, when the electric wire netting breaks down, supply power through DC power supply, can assist the refrigeration, and then maintain the temperature in the freezer.

The second metal plate and the third metal plate can be placed in a space to be heated for heating, for a cold storage space, the second metal plate and the third metal plate can be placed at the side of a condenser, because the temperature of the side of an outdoor machine can reach 40-50 ℃ in the working process of the refrigeration equipment of the cold storage, the temperature of the first metal plate in the room can be reduced to-30 to-40 ℃, because the temperature difference exists between the first metal plate and the second metal plate and the third metal plate, when the temperature difference exists between two nodes of a conductor according to the seebeck effect in the thermoelectric effect, the thermoelectromotive force can be generated in an open circuit, the thermoelectromotive force can charge a direct current power supply, and it needs to be noted that because in a thermoelectric refrigeration system, the current direction flows anticlockwise, when the thermoelectric effect is needed to charge the direct current power supply, for this reason, the present invention is configured to connect a switching circuit to both ends of the dc power supply, and the switching circuit is configured to switch a current flowing direction in the semiconductor circuit, so as to adjust an operating mode of the semiconductor circuit. When the switching circuit is switched to the state that the current flows anticlockwise, the semiconductor circuit works in a refrigeration mode and refrigerates through the cold end; when the switching circuit is switched to the clockwise current flowing, the semiconductor circuit works in a charging mode, and the direct-current power supply is supplied with power through the thermoelectric electromotive force.

It should be noted that fig. 1 shows a scheme of using two semiconductors for refrigeration, and under the idea of the present invention, one or more semiconductors may be further provided for refrigeration, and the refrigeration effect can also be achieved by connecting the semiconductors in series.

Referring to fig. 1, the switch circuit includes a switch S1, a switch S2, a switch S3 and a switch S4, one end of the switch S1 is connected to the second metal plate, the other end of the switch S1 is connected to the third metal plate after being connected in series with the switch S2, one end of the switch S3 is connected to the second metal plate, the other end of the switch S4 is connected to the fourth metal plate after being connected in series with the switch S4, the positive pole of the dc power source is connected between the switch S1 and the switch S2, and the negative pole of the dc power source is connected between the switch S3 and the switch S4;

when the switch S2 and the switch S3 are closed, the current flowing out of the positive electrode of the dc power supply sequentially passes through the third metal plate, the N-type semiconductor, the first metal plate, the P-type semiconductor and the second metal plate and then returns to the negative electrode of the dc power supply, the current flow of the current flows counterclockwise, and the semiconductor circuit operates in a cooling mode;

when the switch S1 and the switch S4 are closed, the current flowing from the positive electrode of the dc power supply sequentially passes through the second metal plate, the P-type semiconductor, the first metal plate, the N-type semiconductor, and the third metal plate and then returns to the negative electrode of the dc power supply, the current flow is clockwise, and the semiconductor circuit operates in the charging mode.

According to the adjustment of the switch circuit, the working process of the utility model can be divided into:

1. when the power grid normally supplies power to the refrigeration system, the switch S1 and the switch S4 are closed, the switch S2 and the switch S3 are opened, and at the moment, the direct-current power supply is supplied with power through the semiconductor circuit;

2. when the power grid fails, the switch S2 and the switch S3 are closed, the switch S1 and the switch S4 are disconnected, and at the moment, the refrigeration house is cooled through the first metal plate to keep the temperature stable;

3. when the charging of the direct current power supply is completed, the switch S1, the switch S2, the switch S3 and the switch S4 are all disconnected, so that the direct current power supply is prevented from being always in a charging state, and electric energy is wasted.

So can reach when the electric wire netting is normal when supplying power to the freezer, can charge to the direct current power supply, when the electric wire netting breaks down, the direct current power supply direction can turn to, and thermoelectric refrigerating system can refrigerate the freezer through thermoelectric effect, guarantees that the temperature in the freezer maintains stably.

Furthermore, the principle of the siberian effect and the peltier effect is combined, so that the refrigerating capacity of the thermoelectric effect can be controlled by adjusting the current (the peltier effect is that the current absorbs/emits heat when flowing through the interface of two different conductors, and the siberian effect is that the thermoelectromotive force is generated in an open circuit when the temperature difference exists between two junctions of the conductors).

The peltier effect of a material is determined by the ratio of the emitted peltier heat to the current, which is expressed as follows: pi = d phip/dI (W/a); wherein φ p is Peltier heat, and I is current.

For a thermocouple composed of two different materials, the peltier coefficient can be expressed as: pi pn = pi P-pi N, where pi P refers to the peltier coefficient of the P-type semiconductor and pi N refers to the peltier coefficient of the N-type semiconductor.

The magnitude of the seebeck effect is related to the voltage applied across the material and the temperature difference across the material, and is expressed by: α = dE/dT (V/K), where E is the voltage applied across the material and T is the temperature difference across the material;

a P-type semiconductor and an N-type semiconductor are used for forming a thermocouple in the thermoelectric refrigeration system, one of alpha P and alpha N of the two materials is negative, the other is positive, the absolute values of the two materials are added, and alpha PN is taken as the Siebert effect value of the whole thermocouple and is as follows: α = | α P | + | α N |.

The siberian effect and the peltier effect are combined to find that the two effects are mutually inverse, the siberian effect means that electromotive force is generated when temperature difference exists in a galvanic couple, and the peltier effect means that temperature difference is generated when current passes through the galvanic couple, so that a relationship exists between a siberian effect value and a peltier coefficient (T is the temperature at a junction point of a semiconductor and a metal plate): pi = α T.

According to the thomson effect: when current passes through a uniform conductor with a temperature gradient, the conductor absorbs/emits heat, the temperature outside a condenser is Th, the temperature in a cold storage is Tc, the current in a thermoelectric refrigeration system loop is I, the cross-sectional area of a semiconductor arm is A, the length of the semiconductor arm is L, and the surface-to-length ratio is r (r = A/L), and at the moment, the Peltier heat expression of a cold end is as follows: phi T = pi PN · I = alpha · Tc · I; the cold side refrigeration capacity expression is as follows (K is the thermal conductance on the thermocouple): phi 0= alpha · I · Tc-K · Δ T-1/2 · I · R;

the influencing factors of thermoelectric refrigeration comprise working current and materials. The refrigerating capacity of the couple is related to the working current I, the larger the Peltier heat is, the smaller the Joule heat loss is, the maximum refrigerating capacity is obtained, the Peltier heat is in direct proportion to the current, and the Joule heat is in direct proportion to the square of the current, so that the working current Imax enabling the maximum refrigerating capacity exists, when thermoelectric refrigeration is carried out, the voltage applied to two ends of the couple is partially used for overcoming the resistance voltage drop V caused by the electronic reason of an electric arm, and the other convenience is needed for overcoming the Siberian thermoelectromotive force Vpn.

Thus, it is known that there is an operating current that maximizes cooling, the expression for which is as follows:

imax = (α P- α N) · Tc/R = α · Tc/R (a), where α is the thermoelectric power rate, Tc is the temperature of the cold junction, and R is the resistance of the entire circuit of the thermoelectric refrigeration circuit.

Referring to fig. 2, for the working current with the maximum refrigerating capacity, the heat flowing into the cold end from the two electric arms is assumed to be phi l, and the working current can be analyzed by a section of uniform-section bar containing a uniform internal heat source, and the bar length is set to be li; a cross-sectional area Ai; the temperature at the two ends of the rod is Th and Tc (Th is more than Tc), the electrical conductivity of the rod is sigma i, and the thermal conductivity is lambda i; the current is Ii, and the other surfaces of the rod have no heat exchange with the outside except the two end surfaces, so the temperature distribution of the rod with uniform internal heat source and uniform cross section is as follows:

tx = Th- (Th-Tc) x/li +1/2 · Ii · x (li-x)/Ai · σ i · λ i, at x = li, the temperature gradient may be represented as (dTx/dx) = - (Th-Tc)/li-1/2 · Ii · li/Ai · σ i · λ i, so the heat that is transmitted into the cold end according to the temperature gradient is the temperature gradient multiplied by the sectional area Ai of the electrical arm and the thermal conductivity λ i, may be represented as Φ li = (Th-Tc)/li · λ i +1/2 · Ii · li · Ai · i/Ai · σ i where i = P, Φ li = lP; i = N, φ li = φ lN, φ l = φ lP + φ lN

The refrigerating capacity phi 0= phi T-phi l can be judged, and the following three formulas are substituted into the refrigerating capacity expression to deduce the working current when the refrigerating capacity is maximum

①φT=πPN·I=α·Tc·I

②φli=（Th-Tc）/li·Ai·λi+1/2·Ii²·li/Ai·σi

③φl=φlP+φlN。

In order to solve the above situation, the utility model adds an adjustable temperature-sensitive resistor in the refrigeration system, the adjustable temperature-sensitive resistor is connected in series between the direct current power supply and the semiconductor circuit, the temperature-sensitive resistor does not work when charging the direct current power supply, and when the thermoelectric refrigeration system works, the resistance value of the temperature-sensitive resistor can be reduced by temperature rise, so that the refrigeration capacity of the refrigeration house can be controlled by controlling the current in the thermoelectric refrigeration loop.

The utility model also provides a refrigerating device which adopts the thermoelectric refrigerating system.

Furthermore, the refrigeration equipment is any one of an air cooler, a condenser, a refrigerator car and a refrigerator.

Compared with the prior art, the semiconductor circuit is arranged, so that the refrigeration system can perform auxiliary refrigeration on the refrigeration house when the power grid fails, the temperature in the refrigeration house is kept unchanged, and meanwhile, when the power grid is normal and the refrigeration house works normally, induced electromotive force can be generated through temperature difference to charge a direct current power supply, so that the energy storage effect is kept.

The above examples are intended only to illustrate specific embodiments of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, and these variations and modifications shall fall within the protective scope of the present invention.

Claims (11)

1. The thermoelectric refrigeration system is characterized by comprising a direct current power supply, a semiconductor circuit connected with the direct current power supply and a switch circuit connected to two ends of the direct current power supply, wherein the switch circuit is used for changing the current flowing direction in the semiconductor circuit so as to switch the semiconductor circuit to be in a refrigeration mode or an energy storage mode.

2. The thermoelectric cooling system according to claim 1, wherein the semiconductor circuit comprises a first metal plate for forming a cold side, a second metal plate and a third metal plate for forming a hot side, a P-type semiconductor connected between the first metal plate and the second metal plate, and an N-type semiconductor connected between the first metal plate and the third metal plate, and two poles of the dc power source are connected to the second metal plate and the third metal plate, respectively.

3. The thermoelectric cooling system according to claim 2, wherein when the dc power source supplies power, carriers at the P-type semiconductor flow from the first metal plate to the second metal plate, carriers at the N-type semiconductor flow from the first metal plate to the third metal plate, the carriers absorb heat when flowing from the first metal plate to the P-type semiconductor and the N-type semiconductor, the first metal plate forms a cold side, the carriers release heat when flowing from the P-type semiconductor and the N-type semiconductor to the second metal plate and the third metal plate, and the second metal plate and the third metal plate forms a hot side.

4. A thermoelectric refrigeration system as set forth in claim 3 wherein the cold side refrigeration capacity is: phi 0= alpha · I · Tc-K · Δ T-1/2 · I · R;

wherein, alpha is the thermoelectric power factor, I is the current of the semiconductor circuit, Tc is the temperature of the cold junction, K is the thermal conductance of the semiconductor, DeltaT is the heat absorbed or released by the metal plate, and R is the resistance of the whole loop of the thermoelectric refrigerating circuit.

5. The thermoelectric cooling system according to claim 3, wherein the DC power source is a rechargeable DC power source, and the semiconductor circuit charges the DC power source when the first metal plate is in temperature difference with the second metal plate and the third metal plate.

6. The thermoelectric cooling system of claim 5 wherein the semiconductor circuit operates in a cooling mode to cool through the cold side when the switching circuit is switched to flow carriers out of the first metal plate;

when the switching circuit is switched to enable the current carriers to flow to the first metal plate, the semiconductor circuit works in an energy storage mode and supplies power to the direct-current power supply through the temperature difference electromotive force.

7. The thermoelectric cooling system according to claim 6, wherein the switch circuit comprises a switch S1, a switch S2, a switch S3 and a switch S4, the switch S1 is connected to the second metal plate at one end and to the third metal plate at the other end in series with the switch S2, the switch S3 is connected to the second metal plate at one end and to the fourth metal plate at the other end in series with the switch S4, the positive pole of the DC power source is connected between the switch S1 and the switch S2, and the negative pole of the DC power source is connected between the switch S3 and the switch S4;

when the switch S2 and the switch S3 are closed, the semiconductor circuit operates in a cooling mode;

when the switch S1 and the switch S4 are closed, the semiconductor circuit operates in a tank mode.

8. The thermoelectric cooling system according to claim 1, further comprising a thermistor connected in series between the switching circuit and the semiconductor circuit, the thermistor controlling current in the semiconductor circuit and thus the amount of cooling when the semiconductor circuit is operating in the cooling mode.

9. The thermoelectric cooling system of claim 1, wherein the semiconductor circuit has a maximum current of: imax = α · Tc/R;

wherein, alpha is the thermoelectric power factor, Tc is the temperature of the cold junction, and R is the resistance of the whole loop of the thermoelectric refrigeration circuit.

10. A refrigeration device, characterized in that it employs a thermoelectric refrigeration system as claimed in any one of claims 1 to 9.

11. The refrigeration appliance of claim 10, wherein the refrigeration appliance is any one of a cold air blower, a condenser, a refrigerator car, and a refrigerator.

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