Large energy-saving oven

Abstract

The large energy-saving oven comprises a shell, an inner container, a main control module and a relay are fixedly arranged in the shell, and a heat preservation layer is arranged between the shell and the inner container; a heat insulation plate is fixedly mounted on the inner top surface of the inner container, a closed air interlayer is formed between the heat insulation plate and the inner top surface of the inner container, a plurality of reflecting covers are fixedly mounted on the lower surface of the heat insulation plate, and an upper heating pipe is fixedly mounted in the center of the lower surface of each reflecting cover; the heat shielding plate and the reflecting cover are both made of specular reflection materials with high melting point and low emissivity. A temperature sensor is fixedly installed in the inner container and connected with a main control module, the main control module is connected with a relay, and the main control module receives signals of the temperature sensor and adjusts the output power of the upper heating pipe through the relay. The heat radiation quantity of the upper wall surface of the inner container can be reduced, so that the heat leakage quantity is reduced, the heat utilization rate of a center load is improved, and the energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to an oven, in particular to a large energy-saving oven. Background Art

[0002] During the operation of the electric oven, the temperature of the heating tube is usually above 650℃. The high temperature of the heating tube makes the radiation heat exchange in the cavity the main mode of heat exchange. A large amount of radiant heat is absorbed by the inner wall, and then conducted and stored by the insulation layer, and finally dissipated to the environment by convection heat exchange. When the upper heating tube is used as the main heating source, the heat leakage of the upper wall is particularly serious. At the same time, due to the indiscriminate transfer of radiant heat in all directions, more heat is absorbed by the oven's own components, resulting in the area of ​​the central load area being much smaller than the wall area, and the radiant heat absorbed by the load is limited. In short, existing electric ovens generally have the problem of large heat leakage to the environment and large heat absorption of their own components, resulting in low energy utilization in the central load area and increased energy consumption.

[0003] At present, the solution to the heat leakage of the oven is to add insulation materials to the outside of the oven. On the one hand, this leads to a sharp increase in the insulation cost of the oven. On the other hand, it increases the thermal resistance between the inner wall and the external environment. The radiation heat exchange between the heating tube and the inner wall is not isolated. A considerable part of the heat will still be converted into wall heat storage and cannot be effectively utilized. It can be seen that the problem of low energy utilization efficiency of electric ovens has not been effectively solved.

[0004] Therefore, it is necessary to design a thermal protection structure that can achieve reliable heat insulation and energy concentration in the limited space of the oven cavity to solve the problems of high heat leakage on the oven wall and low energy utilization of the central load, thereby achieving the purpose of oven energy saving. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a large energy-saving oven that can reduce the amount of heat radiation from the upper wall of the inner tank, thereby reducing heat leakage and improving the utilization rate of heat by the central load, thereby reducing energy consumption.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A large energy-saving oven comprises a shell, an inner container, a main control module and a relay are fixedly arranged inside the shell, and an insulation layer is arranged between the shell and the inner container;

[0008] A heat shield is fixedly mounted on the inner top surface of the inner container, a closed air layer is formed between the heat shield and the inner top surface of the inner container, a plurality of reflective covers are fixedly mounted on the lower surface of the heat shield, and an upper heating pipe is fixedly mounted at the center of the lower surface of the reflective cover;

[0009] The heat shield and the reflector are both made of a specular reflective material with a high melting point and low emissivity;

[0010] A temperature sensor is fixedly installed inside the inner container. The temperature sensor is connected to the main control module, and the main control module is connected to the relay. The main control module receives the signal from the temperature sensor and adjusts the output power of the upper heating tube through the relay.

[0011] Further, the specular reflection material with both high melting point and low emissivity is a specular aluminum plate or a specular stainless steel.

[0012] Further, the heat shield is a rectangular flat plate, and one pair of opposite sides of the flat plate is provided with flanges, and the flanges are fixedly connected to the inner top surface of the inner container;

[0013] The other pair of opposite sides of the flat plate is fixedly connected to the two side walls of the inner container.

[0014] Further, the distance h between the heat shield and the inner top surface of the inner container satisfies the condition: h < a - δ1, where a is the distance between the upper heating tube and the inner top surface of the inner container, and δ1 is the thickness of the reflection cover.

[0015] Further, the thicknesses of both the heat shield and the reflection cover are 0.5 - 1 mm.

[0016] Further, the length of the air interlayer is equal to the length of the inner container, and the width of the air interlayer is greater than the length of the upper heating tube.

[0017] Further, the reflection cover is a hollow semi-cylindrical shape and its opening faces the load center of the inner container.

[0018] Further, the reflection cover is tangent to the outer surface of the upper heating tube, and the upper heating tube and the reflection cover have a common axis of symmetry along the length direction;

[0019] The inclination angle α of the shown reflection cover n satisfies the condition: α n = β n where β n is the angle between the line connecting the geometric center of the nth upper heating tube and the geometric center point of the inner container and the normal line of the oven center plane.

[0020] Further, at least two groups of reflection covers are provided, and the two reflection covers in each group are symmetrically arranged about the normal line of the oven center plane.

[0021] Further, it further includes a hot air assembly. The hot air assembly includes a hot air cover uniformly provided with a plurality of diversion holes. The hot air cover is fixedly connected to the rear wall surface of the inner container to form a cavity, and a hot air blower and a rear heating tube are fixedly arranged inside the cavity.

[0022] Further, it further includes a lower heating tube fixedly installed on the inner bottom wall of the outer shell. The lower heating tube is located between the outer shell and the inner container.

[0023] Compared with the prior art, the present invention has the following technical effects:

[0024] The present invention can reduce the amount of heat radiation from the upper wall of the inner tank, thereby reducing heat leakage and improving the utilization rate of heat by the central load, which is reflected in: on the one hand, by arranging a heat shield with high reflectivity, the radiation heat resistance between the upper heating tube and the top wall of the inner tank is increased, and the heat of the upper heating tube can be reflected to the central load area, thereby reducing the radiation heat leakage of the upper heating tube to the top wall of the inner tank; on the other hand, the heat of the upper heating tube is reflected to the central load area of ​​the oven by a reflective cover, and the reflective cover guides the heat near the upper heating tube, thereby promoting the flow of heat to the load center; on the other hand, the thermal resistance between the upper heating tube and the top wall of the inner tank is increased by an air interlayer, thereby blocking the heat from being transferred to the upper wall of the inner tank, thereby reducing the heat leakage from the upper wall of the inner tank; therefore, the oven of the present invention has higher heat utilization rate and is more energy-saving.

[0025] The present invention sets the reflector cover to be a hollow semi-cylindrical shape, half-covering the upper heating tube and with its opening facing the load center. It can not only more fully focus the heat on the area facing its opening, thereby increasing the radiant heat received by the central load area, but also its structure has a flow-guiding effect, which is beneficial to guiding the heat to flow to the lower part of the oven, thereby reducing the amount of air contact between the heat flow and the left and right walls of the inner pot, and increasing the heat flow to the central load area and the natural convection heat exchange to the central load area. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : A schematic diagram of the internal structure of a large energy-saving oven of the present invention;

[0027] Figure 2 : A schematic structural diagram of a heat shield according to the present invention;

[0028] Figure 3 : A schematic structural diagram of the reflector cover of the present invention;

[0029] Figure 4 : Temperature variation curve of the upper wall surface of the inner tank when the large energy-saving oven of the present invention and the oven of comparative example 1 are operated at a temperature of 190°C;

[0030] Figure 5 : A comparison diagram of the central load radiation heat exchange and natural convection heat exchange of the large energy-saving oven of the present invention and the oven of comparative example 2;

[0031] Figure 6 : A comparison chart of the central load temperature of the large energy-saving oven of the present invention and the oven of Comparative Example 2;

[0032] Figure 7: The energy consumption bar graph of the large energy-saving oven of the present invention, the oven of comparative example 1 and the oven of comparative example 2 when they are operated at the temperature gears of 160° C., 190° C. and 220° C. respectively;

[0033] Figure 8 : A schematic structural diagram of a hot air assembly of the present invention.

[0034] In the figure: 1. heat shield; 2. upper heating tube; 3. air interlayer; 4. hot air assembly; 5. temperature sensor; 6. inner tank; 7. center plane of oven; 8. reflector. DETAILED DESCRIPTION

[0035] The specific contents of the present invention are further explained in detail below in conjunction with embodiments.

[0036] like Figure 1 to Figure 3 and Figure 8 As shown, a large energy-saving oven includes a shell and a hot air component 4, an inner tank 6, a main control module and a relay are fixedly arranged inside the shell, and an insulation layer is provided between the shell and the inner tank 6;

[0037] The hot air assembly 4 includes a hot air hood with a plurality of guide holes evenly opened therein, and the hot air hood is fixedly connected to the rear wall of the inner tank 6 to form a cavity. Figure 8 As shown, a hot air blower and a rear heating pipe are fixedly arranged inside the cavity, and the rear heating pipe is annular and located outside the hot air blower;

[0038] A heat shield 1 is fixedly mounted on the inner top surface of the inner liner 6, and a sealed air sandwich 3 is formed between the heat shield 1 and the inner top surface of the inner liner 6. The heat shield 1 and the air sandwich 3 play a heat insulation role against radiant heat and thermal conduction heat. A plurality of reflective covers 8 are fixedly mounted on the lower surface of the heat shield 1, and an upper heating pipe 2 is fixedly mounted at the center position of the lower surface of the reflective cover 8;

[0039] The heat shield 1 and the reflector 8 are both made of a specular reflective material with a high melting point and a low emissivity, which can block most of the heat radiation of the upper heating tube 2 from being transferred upward, and at the same time, reflect most of the heat radiation downward. At the same time, the heat shield 1 and the reflector 8 are made of a metal material with strong thermal conductivity, which can transfer a small part of the unblocked heat to the surface of the inner tank 6. The still air in the air interlayer 3 acts as a poor thermal conductor, which can reduce the heat conduction, thereby further reducing the heat leakage of the upper wall.

[0040] A temperature sensor 5 is fixedly installed inside the inner tank 6 , and the temperature sensor 5 is connected to the main control module. The main control module receives the signal of the temperature sensor 5 , and adjusts the output power of the upper heating tube 2 according to the real-time temperature transmitted by the sensor 5 .

[0041] Preferably, the mirror reflective material having both a high melting point and a low emissivity is a mirror aluminum plate or a mirror stainless steel.

[0042] Preferably, the reflector 8 is a hollow semi-cylindrical structure, which half-covers the upper heating tube 2 inside, so that the angular coefficient between the upper heating tube 2 and the inner pot 6 is reduced, and most of the radiant heat is concentrated in the area facing the opening of the reflector 8; moreover, the reflector 8 is a hollow semi-cylindrical structure, which has a guiding effect on the heat flow. When the upper heating tube 2 is turned on, the high temperature difference drives the air under the inner pot 6 to produce upward natural convection. Compared with the heat shield 1 alone, the arc surface of the reflector 8 is more conducive to guiding the heat to flow to the lower part of the oven, thereby reducing the amount of air contact between the heat flow and the left and right walls of the inner pot 6, and increasing the heat flow to the central load area, thereby increasing the natural convection heat exchange to the central load area.

[0043] Preferably, Figure 3 As shown, according to the principle of heat transfer by radiation, the radiation amount irradiated from the upper heating tube 2 corresponding to the nth reflector 8 to the center plane of the oven is expressed as:

[0044]

[0045] Where, σ is the Stefan Boltzmann constant, A1 is the area of ​​the semi-cylindrical opening surface of the reflector 8, T is the temperature of the reflector opening surface, A2 is the center plane area of ​​the oven, F n is the angular coefficient between the semi-cylindrical opening surface of the reflector 8 and the center plane of the oven, β n is the angle between the geometric center of the nth upper heating tube 2 and the geometric center of the oven and the normal of the center plane of the oven, α n is the inclination angle of the nth reflector 8, S is the distance between the center of the semi-cylindrical opening surface of the reflector 8 and the center plane of the oven. According to the formula, when the semi-cylindrical opening surface of the reflector 8 is tangent to the upper heating tube 2 and has the same symmetry axis as the upper heating tube 2, the inclination angle α of the nth reflector 8 is n =β n When , the angular coefficient of the two planes is the largest. At this time, the radiation amount irradiated by the upper heating tube 2 corresponding to the nth reflector 8 to the central plane 7 of the oven is the largest, the radiant heat is more focused, the radiant heat received by the central load area is increased, and the energy utilization efficiency of the oven is improved.

[0046] Preferably, Figure 2As shown, the heat shield 1 is a rectangular flat plate, and one set of opposite sides of the flat plate is provided with flanges, which are fixedly connected to the inner top surface of the inner tank 6. The other set of opposite sides of the flat plate is fixedly connected to the two side walls of the inner tank 6, so as to form a sealed air interlayer 3 between the flat plate and the inner top surface of the inner tank 6. The length of the air interlayer 3 is equal to the length of the inner tank 6, and the width of the air interlayer 3 is greater than the length of the upper heating tube 2, which can block the heat of the upper heating tube 2 from being transferred to the inner top wall of the inner tank 6 to the greatest extent and reflect most of the heat to the central load area, thereby reducing the heat leakage of the upper wall surface;

[0047] The inner cavity height H of the air interlayer 3 satisfies the condition: H = h - δ2, where h is the distance between the heat shield 1 and the inner top surface of the inner tank 6, and δ2 is the thickness of the heat shield 1.

[0048] Preferably, the distance h between the heat shield 1 and the inner top surface of the inner tank 6 satisfies the condition: h < a - δ1, where a is the distance between the upper heating tube 2 and the inner top surface of the inner tank 6, and δ1 is the thickness of the reflector 8.

[0049] Preferably, the thicknesses of both the heat shield 1 and the reflector 8 are 0.5 - 1 mm, which reduces the heat absorption of the heat shield 1 and the reflector 8 themselves, reduces the ineffective heat capacity inside the oven, and improves the energy utilization efficiency.

[0050] Preferably, the air interlayer 3 is evacuated to further increase its thermal resistance.

[0051] Preferably, a lower heating tube is provided between the inner bottom wall of the outer shell and the inner tank 6 to facilitate heating the load center from the bottom.

[0052] In the experiment of this embodiment, the heat shield 1 and the reflector 8 as shown are made of a mirror aluminum plate with a reflectivity of 0.9. Figure 2 shown.

[0053] The large-scale energy-saving oven proposed in the embodiment of the present invention includes the following two working modes:

[0054] 1) In the no-wind working mode, the hot air blower and the rear heating tube are turned off, and only the upper heating tube 2 is turned on. The food in the central load area is heated by the upper heating tube 2. During this period: on the one hand, the heat of the upper heating tube 2 is reflected to the central load area by the heat shield 1 and the reflector 8; on the other hand, the reflector 8 guides the hot air flow near the upper heating tube 2 to flow towards the center area of the oven through the arc surface; on the third hand, the air interlayer 3 blocks the heat from being transferred to the upper wall surface of the inner tank, reducing heat leakage;

[0055] During the heating process, the main control module receives the signal of the temperature sensor 5 and adjusts the output power of the upper heating tube 2 through the relay;

[0056] 2) In the wind working mode, turn on the hot air blower and the rear heating tube, the upper heating tube 2 and the lower heating tube to heat the food in the central load area. During this period: the hot air blower will accelerate the flow of heat and make the heat more evenly distributed inside the oven;

[0057] During the heating process, the main control module receives the signal from the temperature sensor 5 and adjusts the output power of the rear heating tube, the upper heating tube 2 and the lower heating tube through the relay.

[0058] In order to verify the performance of the large energy-saving oven proposed in the embodiment of the present invention, in the windless working mode, only the upper heating tube is turned on, and the performance is compared with the ovens of the following comparative examples 1 and 2. The results are shown in FIG. Figures 4 to 7 .

[0059] Comparative Example 1

[0060] The only structural difference between the large energy-saving oven and the embodiment of the present invention is that the heat shielding plate 1 and the reflective cover 8 are not provided inside the inner container 6 .

[0061] Comparative Example 2

[0062] The only structural difference between the large energy-saving oven and the embodiment of the present invention is that no reflective cover 8 is provided inside the inner container 6 .

[0063] The large energy-saving oven proposed in the embodiment of the present invention and the oven of comparative example 1 were respectively set to work at a temperature of 190° C., and then the temperature of the upper wall surface of the inner tank 6 was measured at different time periods. The results are as follows: Figure 4 As shown, it can be seen that the temperature of the upper wall surface of the oven inner tank of the embodiment of the present invention is significantly reduced in both the heating stage and the fluctuation stage compared with the temperature of the upper wall surface of the oven inner tank of the comparative example 1, indicating that the addition of the heat shielding plate 1 enhances the heat insulation capacity of the upper wall surface.

[0064] The simulation test results of the central load radiation heat transfer and natural convection heat transfer of the large energy-saving oven proposed in the embodiment of the present invention and the oven of comparative example 2 are as follows: Figure 5 As shown, the net radiation flux of the oven of the embodiment of the present invention to the load is increased by 10.7% compared with the net radiation flux of the oven of Example 2 to the load; and the convection heat exchange rate of the oven of the embodiment of the present invention to the load is increased by 12.7% compared with the convection heat exchange rate of the oven of Example 2 to the load, indicating that the reflector 8 can effectively improve the radiation capacity of the upper heating tube 2 to the load and the natural convection heat exchange capacity of the heat flow to the load.

[0065] The temperature variation of the central load of the large energy-saving oven proposed in the embodiment of the present invention and the oven of comparative example 2 over time is shown in FIG. Figure 6As shown, it can be seen that under the same heating power and heating time, the load temperature of the oven of the embodiment of the present invention is higher than the load temperature of the oven of comparative example 2, which shows that the reflective cover 8 improves the energy distribution of the oven to the load and improves the energy utilization efficiency of the oven.

[0066] The energy consumption values ​​of the large energy-saving oven proposed in the embodiment of the present invention, the oven of comparative example 1 and the oven of comparative example 2 at three gears (i.e., 160°C, 190°C and 220°C) are compared respectively. The results are as follows: Figure 7 As shown, it can be seen that the energy consumption value of the oven in the embodiment of the present invention is the lowest, the energy consumption value of the oven in comparative example 2 is second, and the energy consumption value of the oven in comparative example 1 is the highest, indicating that the heat shield 1 and the reflector 8 play a good role in heat insulation, energy gathering and flow guidance.

Claims

1. A large energy-saving oven, characterized in that: It comprises a shell, an inner shell is fixedly provided with an inner shell (6), a main control module and a relay, and a heat-insulating layer is provided between the outer shell and the inner shell; A heat shield (1) is fixedly mounted on the inner top surface of the inner container (6), a sealed air sandwich (3) is formed between the heat shield (1) and the inner top surface of the inner container (6), a plurality of reflective covers (8) are fixedly mounted on the lower surface of the heat shield (1), and an upper heating pipe (2) is fixedly mounted at the center of the lower surface of the reflective cover (8); The heat shield (1) and the reflector (8) are both made of a specular reflective material having a high melting point and a low emissivity; A temperature sensor (5) is fixedly installed inside the inner container (6); the temperature sensor (5) is connected to a main control module, which is connected to a relay; the main control module receives a signal from the temperature sensor (5) and adjusts the output power of the upper heating tube (2) through the relay.

2. The large energy-saving oven according to claim 1, characterized in that: The mirror reflective material with high melting point and low emissivity is a mirror aluminum plate or a mirror stainless steel.

3. The large energy-saving oven according to claim 1 or 2, characterized in that: The heat shield (1) is a rectangular flat plate, and a set of opposite sides of the flat plate are provided with folded edges, which are fixedly connected to the inner top surface of the inner container (6); Another set of opposite sides of the flat plate are fixedly connected to two side walls of the inner container (6).

4. The large energy-saving oven according to claim 1 or 2, characterized in that: The thickness of the heat shield (1) and the reflector (8) are both 0.5 to 1 mm.

5. The large energy-saving oven according to claim 1 or 2, characterized in that: The length of the air interlayer (3) is equal to the length of the inner container (5), and the width of the air interlayer (3) is greater than the length of the upper heating tube (2).

6. The large energy-saving oven according to claim 1 or 2, characterized in that: The reflector (8) is in the shape of a hollow semi-cylinder and its opening faces the load center of the inner container (6).

7. The large energy-saving oven according to claim 6, characterized in that: The reflector (8) is tangent to the outer surface of the upper heating tube (2), and the upper heating tube (2) and the reflector (8) have a common symmetry axis along the length direction; The tilt angle α of the reflector (8) is shown n Satisfy the conditions: α n =β n , where β n It is the angle between the line connecting the geometric center of the nth upper heating tube (2) and the geometric center point of the inner pot (5) and the normal of the oven center plane (7).

8. The large energy-saving oven according to claim 7, characterized in that: At least two groups of reflective covers (8) are provided, and the two reflective covers (8) in each group are arranged symmetrically with respect to the normal line of the oven center plane (7).

9. The large energy-saving oven according to any one of claims 1 to 8, characterized in that: It also includes a hot air component (4), which includes a hot air hood with a plurality of guide holes evenly opened thereon, the hot air hood is fixedly connected to the rear wall surface of the inner tank (6) to form a cavity, and a hot air blower and a rear heating pipe are fixedly arranged inside the cavity.

10. The large energy-saving oven according to any one of claims 1 to 8, characterized in that: It also includes a lower heating pipe fixedly mounted on the inner bottom wall of the outer shell, and the lower heating pipe is located between the outer shell and the inner container (6).

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