Heat exchange structure and gas appliance

Abstract

The present invention provides a heat exchange structure and a gas appliance. The heat exchange structure comprises: an inner wall of a combustion chamber, which forms a combustion chamber cavity; an outer wall of a combustion chamber, and a ventilation layer formed between the inner wall of the combustion chamber. The relationship between the thickness δ of the ventilation layer and the surface temperature T of the outer wall of the combustion chamber satisfies the dimensionless formula: T = K1-K2δ 2 +K3δ+δ(K4λ1+K5λ2)*10 ‑3 +K6λ1‑K7λ1 2 ‑K8λ2+K9λ2 2 +K 10 λ1·λ2 Where K1=441~539, K2=2.907~3.553; K3=65.529~80.091; K4=1.89~2.31; K5=3.42~4.18; K6=0.342~0.418; K7=6.3*10 ‑4 ~7.7*10 ‑4 ; K8=0.126~0.154; K9=0.9*10 ‑4 ~1.1*10 ‑4 ;K 10 =1.8*10 ‑4 ~2.2*10 ‑4 ; The ratio of interlayer air volume to total air volume q x The relationship between the thickness of the ventilation layer and the thickness δ satisfies the dimensionless formula: #imgabs0#, where r1 = -0.412 to -0.059, r2 = 0.042 to 0.369, and r3 = -18.598 to -4.924. The heat exchange structure of the present invention can both ensure the overall thermal efficiency requirements and meet the temperature limit requirements on the surface of the combustion chamber outer wall.

Description

Technical Field

[0001] The present invention relates to the technical field of household electrical appliances, and in particular to a heat exchange structure and a gas appliance. Background Art

[0002] Low carbon emissions, green and clean energy, high efficiency, and safety are the main themes of current energy development and utilization. Natural gas is an efficient, environmentally friendly, and economical energy source. In recent years, the development and utilization of natural gas has achieved fruitful results, and the urban gasification rate has continued to increase.

[0003] Gas water heaters, as a widely used gas appliance, play a crucial role in the efficient utilization of gas resources. These small thermal devices utilize the heat released by gas combustion to heat domestic water to the desired temperature through a heat exchanger. They offer numerous advantages, including high efficiency, rapid water delivery, stable water temperature regulation, and continuous operation.

[0004] Working Principle of a Gas Water Heater: A gas water heater primarily consists of a combustion system, heat exchange system, exhaust system, and temperature control system. Gas enters the combustion chamber through a nozzle, where it mixes with air and burns, producing flue gas with a high level of heat. This flue gas exchanges heat with the combustion chamber, raising the water temperature in the coil. The flue gas then exchanges heat with the cold water in the heat exchanger, heating it to a suitable temperature for consumption. After this heat exchange, the flue gas cools down and is discharged through the exhaust port.

[0005] The heat exchange system, consisting of the combustion chamber and heat exchanger, primarily exchanges heat with the high-temperature flue gas. The heat exchanger accounts for approximately 80% of the total heat exchange. The heat exchange system design affects the combustion chamber surface temperature and the thermal efficiency of the gas water heater. Gas water heaters operate at high temperatures for extended periods, with combustion chamber surface temperatures reaching as high as 300°C. This prolonged high-temperature operation accelerates material aging, degrading insulation effectiveness, causing component damage, and creating safety hazards.

[0006] In order to ensure that the surface temperature of the combustion chamber is within the temperature limit requirements, it is necessary to reduce the heat transfer efficiency from the inner wall to the outer wall of the combustion chamber. However, if the heat transfer efficiency from the inner wall to the outer wall of the combustion chamber is reduced, the thermal efficiency of the gas water heater will be reduced. Therefore, there is a lack of a solution in the existing technology that allows the gas appliance to ensure the thermal efficiency requirements of the entire machine and meet the temperature limit requirements of the surface of the outer wall of the combustion chamber. Summary of the Invention

[0007] The main purpose of the present invention is to provide a heat exchange structure and a gas appliance, which can not only ensure the thermal efficiency requirements of the entire machine, but also meet the temperature limit requirements of the surface of the outer wall of the combustion chamber.

[0008] In order to achieve the above object, according to one aspect of the present invention, a heat exchange structure is provided, comprising:

[0009] The inner wall of the combustion chamber, the inner wall of the combustion chamber forms the combustion chamber cavity;

[0010] The outer wall of the combustion chamber is arranged on the outer side of the inner wall of the combustion chamber and forms a ventilation interlayer with the inner wall of the combustion chamber, and the ventilation interlayer has an interlayer channel;

[0011] The heat exchanger is arranged downstream of the fluid flowing through the combustion chamber, and the fluid flowing out of the inner cavity of the combustion chamber exchanges heat with the liquid in the heat exchanger, and the interlayer channel is connected to the heat exchanger;

[0012] The relationship between the thickness δ of the ventilation interlayer and the surface temperature T of the outer wall of the combustion chamber satisfies the dimensionless formula:

[0013] T=K1-K2δ 2 +K3δ+δ(K4λ1+K5λ2)*10 -3 +K6λ1-K7λ1 2 -K8λ2+K9λ2 2 +K 10 λ1·λ2

[0014] Among them, K1=441~539, K2=2.907~3.553; K3=65.529~80.091; K4=1.89~2.31; K5=3.42~4.18;

[0015] K6=0.342~0.418; K7=6.3*10 -4 ~7.7*10 -4 ; K8=0.126~0.154; K9=0.9*10 -4 ~1.1*10 -4 ;

[0016] K 10 =1.8*10 -4 ~2.2*10 -4 ;

[0017] T is the temperature of the monitoring point on the outer wall of the combustion chamber, in °C; δ is the thickness of the ventilation interlayer, in mm; λ1 is the thermal conductivity of the outer wall of the combustion chamber, in W / (m·K); λ2 is the thermal conductivity of the inner wall of the combustion chamber, in W / (m·K);

[0018] The ratio of interlayer air volume to total air volume q x The relationship between the thickness of the ventilation interlayer δ satisfies the dimensionless formula:

[0019]

[0020] Among them, r1=-0.412~-0.059; r2=0.042~0.369; r3=-18.598~-4.924.

[0021] Further,

[0022] K1=490±4.41; K2=3.23±0.02907; K3=72.81±0.65529;

[0023] K4=2.1±0.0189; K5=3.8±0.0342; K6=0.38±0.00342;

[0024] K7=0.0007±0.00005; K8=0.14±0.00126;

[0025] K9=0.0001±0.00005; K 10 =0.0002±0.00005.

[0026] Further,

[0027] K1=490; K2=3.23; K3=72.81;

[0028] K4=2.1; K5=3.8; K6=0.38;

[0029] K7=0.0007; K8=0.14; K9=0.0001; K 10 =0.0002.

[0030] Furthermore, when T≤250℃, the thickness δ of the ventilation interlayer satisfies the dimensionless formula:

[0031] 3.23δ 2 -72.81δ-δ(2.1λ1+3.8λ2)*10 -3 -0.38λ1+0.0007λ1 2 +0.14λ2-0.0001λ2 2 -0.0002λ1·λ2≥240.

[0032] Furthermore, T is the maximum temperature value of the monitoring points on the outer wall of the combustion chamber; or, T is the average temperature value of the monitoring points on the outer wall of the combustion chamber.

[0033] Further,

[0034] r1=-0.21988±0.01545;

[0035] r2=0.19118±0.01443;

[0036] r3=-11.18943±0.57182.

[0037] Further,

[0038] r1 = -0.21988;

[0039] r2=0.19118;

[0040] r3=-11.18943.

[0041] Further,

[0042] The thermal efficiency η is determined by the ratio of the interlayer air volume to the total air volume q x Get;

[0043] When the outer wall of the combustion chamber is copper and the inner wall of the combustion chamber is copper, when η ≥ 89.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 5.15mm ≤ δ ≤ 8.8mm; when η ≥ 92.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 5.15mm ≤ δ ≤ 5.4mm;

[0044] When the outer wall of the combustion chamber is copper and the inner wall of the combustion chamber is stainless steel, when η ≥ 89.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 5.2mm ≤ δ ≤ 8.8mm; when η ≥ 92.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 5.2mm ≤ δ ≤ 5.4mm;

[0045] When the outer wall of the combustion chamber is made of stainless steel and the inner wall of the combustion chamber is made of stainless steel, when η ≥ 89.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 4.17mm ≤ δ ≤ 8.8mm; when η ≥ 92.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 4.17mm ≤ δ ≤ 5.4mm;

[0046] When the outer wall of the combustion chamber is stainless steel and the inner wall of the combustion chamber is copper, when η≥89.5% and T≤250℃, the thickness δ of the ventilation interlayer satisfies 3.52mm≤δ≤8.8mm; when η≥92.5% and T≤250℃, the thickness δ of the ventilation interlayer satisfies 3.52mm≤δ≤5.4mm.

[0047] Furthermore, the outer wall of the combustion chamber and the outer wall of the combustion chamber are both block structures, and the two are arranged in a one-to-one correspondence. The corresponding outer wall of the combustion chamber and the inner wall of the combustion chamber are fixedly connected together to form a ventilation interlayer. The ventilation interlayers of different blocks are isolated from each other, and a separate ventilation interlayer has an interlayer channel that runs through the upper and lower parts.

[0048] Furthermore, a connecting block is provided between the outer wall of the combustion chamber and the inner wall of the combustion chamber. The outer wall of the combustion chamber and the inner wall of the combustion chamber are fixedly connected by the connecting block, and the thickness δ of the ventilation interlayer is limited by the connecting block.

[0049] Furthermore, the connecting block is arranged on the inner wall of the combustion chamber and protrudes from the inner wall of the combustion chamber toward the outer wall of the combustion chamber. A first connecting hole is provided at the vertex position of the protruding structure of the connecting block, and a second connecting hole is provided on the outer wall of the combustion chamber corresponding to the first connecting hole. The outer wall of the combustion chamber and the inner wall of the combustion chamber are fixedly connected by screws provided in the first connecting hole and the second connecting hole.

[0050] According to another aspect of the present invention, there is provided a heat exchange structure comprising:

[0051] The inner wall of the combustion chamber, the inner wall of the combustion chamber forms the combustion chamber cavity;

[0052] The outer wall of the combustion chamber is arranged on the outer side of the inner wall of the combustion chamber and forms a ventilation interlayer with the inner wall of the combustion chamber, and the ventilation interlayer has an interlayer channel;

[0053] The heat exchanger is arranged downstream of the fluid flowing through the combustion chamber, and the fluid flowing out of the inner cavity of the combustion chamber exchanges heat with the liquid in the heat exchanger, and the interlayer channel is connected to the heat exchanger;

[0054] The thickness of the ventilation interlayer δ and the surface temperature of the combustion chamber wall are T, and the ratio of the interlayer air volume to the total air volume is q x ;The thermal efficiency of the heat exchange structure is η;

[0055] When the outer wall of the combustion chamber is copper and the inner wall of the combustion chamber is copper, when η ≥ 89.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 5.15mm ≤ δ ≤ 8.8mm; when η ≥ 92.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 5.15mm ≤ δ ≤ 5.4mm;

[0056] When the outer wall of the combustion chamber is copper and the inner wall of the combustion chamber is stainless steel, when η ≥ 89.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 5.2mm ≤ δ ≤ 8.8mm; when η ≥ 92.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 5.2mm ≤ δ ≤ 5.4mm;

[0057] When the outer wall of the combustion chamber is made of stainless steel and the inner wall of the combustion chamber is made of stainless steel, when η ≥ 89.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 4.17mm ≤ δ ≤ 8.8mm; when η ≥ 92.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer satisfies 4.17mm ≤ δ ≤ 5.4mm;

[0058] When the outer wall of the combustion chamber is stainless steel and the inner wall of the combustion chamber is copper, when η≥89.5% and T≤250℃, the thickness δ of the ventilation interlayer satisfies 3.52mm≤δ≤8.8mm; when η≥92.5% and T≤250℃, the thickness δ of the ventilation interlayer satisfies 3.52mm≤δ≤5.4mm.

[0059] According to another aspect of the present invention, a gas appliance is provided, comprising a heat exchange structure, which is the above-mentioned heat exchange structure.

[0060] By applying the technical solution of the present invention, the heat exchange structure associates the surface temperature T of the outer wall of the combustion chamber with the thickness δ of the ventilation interlayer, so that the thickness setting range of the ventilation interlayer can be determined by the set value of the surface temperature T of the outer wall of the combustion chamber and the thermal conductivity coefficient of the outer wall of the combustion chamber and the outer wall of the combustion chamber. The thickness of the ventilation interlayer can be set according to the characteristics of different materials, so that the designed thickness of the ventilation interlayer matches the material characteristics, which can reduce the outer surface temperature of the combustion chamber of the external heat exchange structure without coils, and effectively ensure that the surface temperature T of the outer wall of the combustion chamber can meet the outer surface temperature limit requirement; at the same time, the heat exchange structure sets the ratio of the interlayer air volume to the total air volume q x It is associated with the thickness of the ventilation interlayer δ, so that the ratio of the interlayer air volume to the total air volume q can be determined by setting the thickness of the ventilation interlayer x , and the ratio of the mezzanine air volume to the total air volume q x It can also have a greater impact on the thermal efficiency, so the thermal efficiency can be guaranteed to meet the requirements by setting the thickness of the ventilation interlayer; since the thickness of the ventilation interlayer will not only have a greater impact on the outer surface temperature of the combustion chamber, but also affect the combustion efficiency of the inner cavity of the combustion chamber, the increase in the thickness of the ventilation interlayer will increase the interlayer air volume allocated to the ventilation interlayer, and the increase in the interlayer air volume will improve the cooling effect of the ventilation interlayer, thereby reducing the outer surface temperature of the combustion chamber, but at the same time will reduce the combustion efficiency of the inner cavity of the combustion chamber, conversely, the reduction in the thickness of the ventilation interlayer will reduce the interlayer air volume allocated to the ventilation interlayer, and the reduction in the interlayer air volume will reduce the cooling effect of the ventilation interlayer, thereby increasing the outer surface temperature of the combustion chamber, but at the same time will increase the combustion efficiency of the inner cavity of the combustion chamber. Therefore, by reasonably setting the thickness of the ventilation interlayer, the temperature of the outer surface of the combustion chamber can reach the temperature limit requirement, and at the same time the thermal efficiency requirement of the whole machine can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0062] Figure 1 A three-dimensional exploded structural diagram of a heat exchange structure according to an embodiment of the present invention is shown;

[0063] Figure 2 A schematic diagram showing a heat exchange structure according to an embodiment of the present invention is shown;

[0064] Figure 3 A heat transfer process analysis diagram of a heat exchange structure according to an embodiment of the present invention is shown;

[0065] Figure 4 A thermal resistance network diagram of a heat exchange structure according to an embodiment of the present invention is shown;

[0066] Figure 5 A diagram showing a ventilated sandwich structure of a heat exchange structure according to an embodiment of the present invention is shown;

[0067] Figure 6 A second structural diagram of the ventilation interlayer of the heat exchange structure according to an embodiment of the present invention is shown;

[0068] Figure 7 A third structural diagram showing a ventilation interlayer of a heat exchange structure according to an embodiment of the present invention;

[0069] Figure 8 A fourth structural diagram showing a ventilation interlayer of a heat exchange structure according to an embodiment of the present invention;

[0070] Figure 9 A graph showing the effect of the thickness of the ventilation interlayer on the temperature of the monitoring point of the heat exchange structure according to an embodiment of the present invention is shown.

[0071] The above drawings include the following reference numerals:

[0072] 1. Inner wall of combustion chamber; 2. Inner wall of combustion chamber; 3. Ventilation interlayer; 4. Connecting pipe; 5. Heat exchanger; 6. Connecting block. DETAILED DESCRIPTION

[0073] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0074] like Figures 1 to 4 As shown, the present invention provides a heat exchange structure comprising: a combustion chamber inner wall 1, which encloses a combustion chamber cavity; a combustion chamber inner wall 2, which surrounds the combustion chamber inner wall 1 and forms a ventilation interlayer 3 with the combustion chamber inner wall 1, with the ventilation interlayer 3 having an interlayer channel; and a heat exchanger 5, which is disposed downstream of the fluid flowing through the combustion chamber. The fluid flowing out of the combustion chamber cavity exchanges heat with the liquid in the heat exchanger 5, and the interlayer channel is connected to the heat exchanger 5. The present invention is described using a gas appliance having this heat exchange structure as an example.

[0075] When the gas appliance is operating, the air entering the heat exchange structure is divided into two parts: one part enters the combustion chamber to mix with the gas, and the other part enters the ventilation interlayer 3. The gas and air mix in a certain proportion and burn in the burner to produce high-temperature flue gas. Driven by the fan, the high-temperature flue gas first enters the combustion chamber. Through convection and radiation, the high-temperature flue gas transfers heat to the combustion chamber inner wall 1. A ventilation interlayer 3 is formed between the combustion chamber inner wall 1 and the combustion chamber outer wall 2. The air in the ventilation interlayer 3 enters from the bottom of the combustion chamber. This circulating air effectively prevents heat from the combustion chamber from radiating outward, reducing the temperature of the combustion chamber outer wall. The air then flows into the heat exchanger to participate in heat exchange.

[0076] The fluid in the combustion chamber undergoes heat conduction, convection and radiation. Due to the action of the fan, the air in the ventilation interlayer 3 has a certain speed along the air flow direction. Therefore, the convection heat transfer in the ventilation interlayer 3 is a mixed convection heat transfer, including natural convection heat transfer and forced convection heat transfer. The interlayer air duct can be regarded as a vertical flat plate. Figure 3 Shows the heat transfer situation on one side of the combustion chamber. Assuming that the heat transfer process is uniform, the ambient temperature outside the combustion chamber is t f1 , the convection heat transfer coefficient outside the combustion chamber h1, the thermal conductivity coefficient of the combustion chamber outer wall 2 λ1, the thickness of the combustion chamber outer wall 2 δ1, and the temperature of the combustion chamber outer wall 2 close to the combustion chamber is t w1 The temperature of the other side of the combustion chamber outer wall 2 close to the combustion chamber inner wall 1 is t w2 The thickness of the ventilation interlayer 3 is δ, the convection heat transfer coefficient of the ventilation interlayer 3 is h, and the temperature inside the ventilation interlayer 3 is t f ; Combustion chamber inner temperature t f2 ; The convection heat transfer coefficient inside the combustion chamber is h2; the thermal conductivity coefficient of the combustion chamber inner wall 1 is λ2; the thickness of the combustion chamber inner wall 1 is δ2, and the temperature of the side of the combustion chamber inner wall 1 close to the ventilation interlayer 3 is t w3 The temperature of the other side of the combustion chamber inner wall 1 close to the combustion chamber is t w4 .

[0077] The research found that the relationship between the composite heat transfer coefficient k and the thickness δ of the ventilation interlayer 3 satisfies the dimensionless formula:

[0078]

[0079] Where φ=Ak(t f2 -t f1 );

[0080] k is the composite heat transfer coefficient, unit is W / (m 2 ·K); Φ is the heat flow in the heat transfer process, the unit is W; t f1 is the ambient temperature outside the combustion chamber, in °C; h1 is the convection heat transfer coefficient outside the combustion chamber, in W / (m2 ·K); λ1 is the thermal conductivity of the outer wall 2 of the combustion chamber, in W / (m·K); δ1 is the thickness of the outer wall 2 of the combustion chamber, in mm; t f2 is the temperature inside the combustion chamber, in °C; h2 is the convection heat transfer coefficient inside the combustion chamber, in W / (m 2 ·K); λ2 is the thermal conductivity of the inner wall 1 of the combustion chamber, in W / (m·K); δ2 is the thickness of the inner wall 1 of the combustion chamber, in mm; A is the surface area of the heat transfer surface of the inner wall 1 of the combustion chamber, in m 3 ; m, n, m' are coefficients related to convective heat transfer coefficient, heat transfer area, flow rate, etc.

[0081] The heat transfer mode of the high-temperature flue gas from the inner cavity of the combustion chamber is as follows: the high-temperature flue gas in the inner cavity of the combustion chamber undergoes convection heat exchange and radiation heat transfer with the side of the inner wall 1 of the combustion chamber close to the ventilation interlayer 3, the side of the inner wall 1 of the combustion chamber close to the ventilation interlayer 3 and the other side of the inner wall 1 of the combustion chamber close to the inner cavity of the combustion chamber undergo heat conduction, the other side of the inner wall 1 of the combustion chamber close to the inner cavity of the combustion chamber undergoes convection heat exchange and radiation heat transfer with the fluid in the ventilation interlayer 3, the fluid in the ventilation interlayer 3 undergoes convection heat exchange and radiation heat transfer with the other side of the outer wall 2 of the combustion chamber close to the inner wall 1 of the combustion chamber, the other side of the outer wall 2 of the combustion chamber close to the inner wall 1 of the combustion chamber undergoes heat conduction with the side of the outer wall 2 of the combustion chamber close to the outside of the combustion chamber, and the side of the outer wall 2 of the combustion chamber close to the outside of the combustion chamber undergoes convection heat exchange and radiation heat transfer with the environment outside the combustion chamber. All of these are regarded as a steady-state heat transfer process, and each link is in a series manner. Assume that the heat transfer surface area of the combustion chamber inner wall 1 is A. Due to the fan, the fluids in both the ventilation interlayer and the combustion chamber cavity have certain velocities, representing mixed convection heat transfer. m, m', and n are coefficients related to the convection heat transfer coefficient, heat transfer area, and airflow velocity. Analysis of the thermal resistance of the heat transfer process reveals that the entire heat transfer process is related to the combustion chamber wall thickness, wall material (reflected in the thermal conductivity), ventilation interlayer thickness, and convection heat transfer coefficient. The more intense the heat transfer process, the greater the heat transfer coefficient, and vice versa. The magnitude of the heat transfer coefficient is related to the type of fluid and the flow rate. 1 / (Ak) is the heat transfer resistance. The formula shows that the heat transfer resistance is related to the heat transfer area, convection heat transfer coefficient, the distance between the two plates (thickness of the ventilation interlayer), and the combustion chamber wall material (thermal conductivity). The combined heat transfer coefficient, k, is directly proportional to the convection heat transfer coefficient and the combustion chamber cavity thermal conductivity, and inversely proportional to the ventilation interlayer thickness. This shows that the thickness of the ventilation interlayer 3 affects the surface temperature of the outer wall 2 of the combustion chamber of the heat exchange structure.

[0082] The air entering the heat exchange structure is divided into two parts. One part enters the combustion chamber and mixes with the gas before burning to form high-temperature flue gas, and the other part enters the ventilation interlayer 3. The heat exchanger 5 is set downstream of the fluid flowing through the combustion chamber, so the high-temperature flue gas flowing through the combustion chamber enters the heat exchanger 5. The high-temperature flue gas transfers heat to the finned tube heat exchanger through convection and radiation. The heat is transferred to the copper tube by heat conduction, and then the copper tube transfers the heat to the flowing water by convection, so that the water temperature quickly reaches the required use temperature. In addition, the interlayer channel is connected to the heat exchanger 5, and enters the ventilation interlayer 3 to undergo convection heat exchange and radiation heat transfer with the combustion chamber inner wall 1, the combustion chamber outer wall 2, the combustion chamber inner wall, and the combustion chamber outer environment. The temperature of this part of gas increases from the flow of gas from the interlayer channel to the outflow, and its temperature is still higher than the temperature of the water in the heat exchanger. Therefore, the air flowing through the interlayer channel will also enter the heat exchanger 5 for heat exchange. Therefore, both the high-temperature flue gas and the high-temperature gas flowing through the interlayer channel enter the heat exchanger 5 and exchange heat with the liquid in the heat exchanger 5. The heat exchange ratio Qx during the heat exchange process is the ratio of the heat absorbed by the liquid flowing through the heat exchanger 5 to the heat input by the gas. In the present invention, the liquid in the heat exchanger is water, and the heat exchange ratio Qx is the ratio of the heat absorbed by the water flowing through the heat exchanger 5 to the heat input by the gas.

[0083] Due to factors such as gas temperature and pressure, the heat input to the heat exchanger 5 cannot be completely absorbed by the water in the heat exchanger 5, so the thermal efficiency η of the heat exchange structure is related to the heat exchange ratio Q. x The relationship between satisfies the dimensionless formula:

[0084] η=Q x ×α×β×100%;

[0085]

[0086] in

[0087]

[0088] α is related to t g Correlation coefficient, t g The gas temperature in the gas flow meter is measured experimentally in °C; P a is the actual atmospheric pressure, in KPa; β is the g The correlation coefficient, p g is the gas pressure, unit is KPa; S is the temperature t g The saturation pressure at the time of measurement is in KPa; V is the actual measured gas flow rate in m 3 / min; Q1 is the actual measured lower calorific value of the gas, the unit is MJ / m 3 ; M is the output of hot water, unit is kg / min; C is the specific heat of water, 4.19×10 -3MJ / (kg·k);t s2 is the outlet water temperature, in °C; t s1 is the inlet water temperature, in °C.

[0089] Since the heat absorbed by water is related to the water flow rate and the water temperature at the inlet and outlet of the heat exchanger 5, and the heat input by gas is related to the gas flow rate, the thermal efficiency of the heat exchange structure is related to the gas flow rate, the water flow rate, and the water temperature at the inlet and outlet of the heat exchanger 5. In the convective heat exchange of air in the ventilation interlayer 3, if the thickness of the ventilation interlayer 3 is too small, the ratio of the inlet cross-sectional area of the ventilation interlayer 3 to the total inlet cross-sectional area is small, and the air flow entering the ventilation interlayer 3 is small. During the flow heat exchange process, less heat is exchanged, that is, less heat is taken away. Then, the cooling effect on the combustion chamber wall is small and the temperature requirement cannot be met. If the thickness of the ventilation interlayer 3 is too large, the ratio of the inlet cross-sectional area of the ventilation interlayer 3 to the total inlet cross-sectional area is large, and the air flow entering the ventilation interlayer 3 is large. Less air participates in the heat exchange in the combustion chamber cavity, and the gas cannot be fully burned, which will affect the smoke emission, the heat entering the heat exchange cavity is small, and the water absorbs less heat, which will eventually affect the thermal efficiency of the heat exchange structure. Therefore, it is necessary to design a reasonable ventilation interlayer thickness to meet both the combustion chamber surface temperature limit requirements and thermal efficiency requirements of the gas appliance. x As an important parameter for regulating thermal efficiency, it can play an important role in regulating thermal efficiency.

[0090] Based on the above analysis, the present invention utilizes Q x To design the thickness of the ventilation interlayer δ, a satisfactory heat transfer ratio Q can be obtained. x , thereby ensuring the thermal efficiency η of the heat exchange structure.

[0091] like Figures 1 to 8 As shown, the present invention provides a heat exchange structure, comprising: a combustion chamber inner wall 1, the combustion chamber inner wall 1 enclosing a combustion chamber cavity; a combustion chamber outer wall 2, arranged on the outside of the combustion chamber inner wall 1 and forming a ventilation interlayer 3 between the combustion chamber inner wall 1, the ventilation interlayer 3 having an interlayer channel; the thickness δ of the ventilation interlayer 3 and the heat exchange ratio Q x The relationship between satisfies the dimensionless formula S10:

[0092]

[0093] Among them, k1=0.72~0.92; k2=-0.016~-0.013; k3=-8.61~-7.05.

[0094] In one embodiment,

[0095] k1=0.82432±2.206*10 -4;k2=-0.01476±1.884*10 -4 ;k3=-7.83075±0.05731.

[0096] In one embodiment, k1=0.82432; k2=-0.01476; k3=-7.83075, and the dimensionless formula S11 is:

[0097]

[0098] In the above embodiment, the fluid entering the combustion chamber mainly includes air and gas, wherein the air is divided into two parts. One part of the air is mixed with the gas and then burned in the burner to form high-temperature flue gas. The high-temperature flue gas flows through the inner cavity of the combustion chamber and enters the heat exchanger 5 to exchange heat with the fluid in the heat exchanger 5. The other part of the air enters the ventilation interlayer 3 and exchanges heat with the inner wall 1 of the combustion chamber and the outer wall 2 of the combustion chamber in the interlayer channel of the ventilation interlayer 3. After the heat exchange, the air in the interlayer channel enters the heat exchanger 5 to exchange heat with the fluid in the heat exchanger 5. Among them, the air entering the combustion chamber is the total air volume; the air entering the inner cavity of the combustion chamber is the combustion air volume; the air entering the interlayer channel of the ventilation interlayer 3 is the interlayer air volume; and the total air volume is the sum of the combustion air volume and the interlayer air volume. When the total air volume remains unchanged, as the thickness of the ventilation interlayer 3 increases, the interlayer air volume gradually increases, and the combustion air volume gradually decreases, which may lead to incomplete combustion and low heat exchange efficiency. However, at this time, due to the large interlayer air volume, the cooling effect is obvious, so the outer surface temperature of the combustion chamber can be significantly reduced; when the total air volume remains unchanged, as the thickness of the ventilation interlayer 3 decreases, the interlayer air volume gradually decreases, and the combustion air volume gradually increases, which can ensure sufficient combustion and improve thermal efficiency. At this time, the interlayer air volume is small and the cooling effect is weak, so the outer surface temperature of the combustion chamber will increase. On this basis, considering the impact of changes in interlayer air volume and combustion air volume on thermal efficiency, the above-mentioned thickness δ of the ventilation interlayer 3 and the heat exchange ratio Q are obtained. x The relationship between them.

[0099] The heat exchange structure will heat exchange ratio Q x It is associated with the thickness δ of the ventilation interlayer 3, so that the heat exchange ratio Q can be determined by setting the thickness δ of the ventilation interlayer 3. x , and the heat transfer ratio Q x It can also have a greater impact on the thermal efficiency. Therefore, the thickness δ of the ventilation interlayer 3 can be set to ensure that the thermal efficiency meets the requirements. The present invention uses the above formula to calculate the thickness δ of the ventilation interlayer 3 and the heat exchange ratio Q. x , and thermal efficiency η, and can ensure the thermal efficiency requirements of the whole machine by optimizing the thickness δ of the ventilation interlayer 3. The structure is more reasonable, and a clear and accurate design scheme of the ventilation interlayer 3 that meets the design requirements can be provided, thereby realizing the optimized design of the heat exchange structure.

[0100] In addition, the thickness δ of the ventilation interlayer 3 will have a great impact on the outer surface temperature of the combustion chamber. An increase in the thickness δ of the ventilation interlayer 3 will increase the interlayer air volume allocated to the ventilation interlayer 3. The increase in the interlayer air volume will improve the cooling effect of the ventilation interlayer 3, thereby reducing the outer surface temperature of the combustion chamber, but at the same time will reduce the combustion efficiency of the inner cavity of the combustion chamber. Conversely, a decrease in the thickness δ of the ventilation interlayer 3 will reduce the interlayer air volume allocated to the ventilation interlayer 3. The decrease in the interlayer air volume will reduce the cooling effect of the ventilation interlayer 3, thereby increasing the outer surface temperature of the combustion chamber, but at the same time will increase the combustion efficiency of the inner cavity of the combustion chamber. Therefore, by reasonably setting the thickness δ of the ventilation interlayer 3, the temperature of the outer surface of the combustion chamber can reach the temperature limit requirement while ensuring the thermal efficiency requirement of the whole machine.

[0101] In one embodiment, the heat exchange ratio Q x The relationship between the air volume and the mezzanine volume satisfies the dimensionless formula S20:

[0102]

[0103] Where j1 = 0.673 ~ 1.148; j2 = -0.259 ~ 0.065; j3 = -1.967 ~ 0.339; where q x It is the ratio of mezzanine air volume to total air volume.

[0104] In one embodiment,

[0105] j1=0.89495±0.01488; j2=-0.0886±0.0147; j3=-0.7399±0.1048.

[0106] In one embodiment, j1 = 0.89495; j2 = -0.0886; j3 = -0.7399, at this time, the heat exchange ratio Q x The relationship between the air volume of the interlayer satisfies the dimensionless formula S21:

[0107]

[0108] This formula defines the heat transfer ratio Q x The ratio of mezzanine air volume to total air volume q x The relationship between Q x Affects the thermal efficiency η, Q of the heat exchange structure x The larger the value, the higher the thermal efficiency η, Q x The smaller the value, the lower the thermal efficiency η; the ratio of the interlayer air volume to the total air volume q xThe interlayer air volume affects the outer surface temperature of the combustion chamber. The greater the interlayer air volume, the more significant the reduction in the outer surface temperature of the combustion chamber. The smaller the interlayer air volume, the less effective the reduction in the outer surface temperature of the combustion chamber. The two parameters are interrelated, and by defining the relationship between them, it is possible to meet the outer surface temperature limit requirements while maintaining the overall thermal efficiency requirements of the machine.

[0109] The ratio of interlayer air volume to total air volume q x The relationship between the thickness δ of the ventilation interlayer 3 satisfies the dimensionless formula S30:

[0110]

[0111] Among them, r1=-0.412~-0.059; r2=0.042~0.369; r3=-18.598~-4.924.

[0112] In one embodiment,

[0113] r1=-0.21988±0.01545; r2=0.19118±0.01443; r3=-11.18943±0.57182.

[0114] In one embodiment, r1 = -0.21988; r2 = 0.19118; r3 = -11.18943, at this time, the ratio of the interlayer air volume to the total air volume q x The relationship between the thickness δ of the ventilation interlayer 3 satisfies the dimensionless formula S31:

[0115]

[0116] By limiting the ratio of the mezzanine air volume to the total air volume q x The relationship between the thickness δ of the ventilation interlayer 3 and the thickness δ of the ventilation interlayer 3 can be used to adjust the ratio of the interlayer air volume to the total air volume q by reasonably designing the thickness δ of the ventilation interlayer 3 x , thereby achieving the regulation of the outer surface temperature of the combustion chamber, so that the design of the thickness δ of the ventilation interlayer 3 can meet the outer surface temperature limit requirements of the combustion chamber.

[0117] In this embodiment, the heat exchange ratio Q x The relationship between the thickness δ of the ventilation interlayer 3 is determined by the heat exchange ratio Q x The relationship between the mezzanine air volume and the ratio of the mezzanine air volume to the total air volume q xThe formula comprehensively considers the relationship between the outer surface temperature of the combustion chamber and the thermal efficiency and the thickness δ of the ventilation interlayer 3. By optimizing the thickness δ of the ventilation interlayer 3, it can be more effectively ensured that the heat exchange structure can meet the outer surface temperature limit requirements of the combustion chamber and the thermal efficiency requirements of the whole machine.

[0118] In one embodiment, the heat exchange structure further includes a connecting pipe 4, which includes a liquid inlet pipe and a liquid outlet pipe. The liquid inlet pipe is connected to the inlet of the heat exchanger 5, and the liquid outlet pipe is connected to the outlet of the heat exchanger 5. In this embodiment, the liquid inlet pipe and the liquid outlet pipe of the connecting pipe 4 are both located outside the combustion chamber. The liquid inlet pipe of the connecting pipe 4 is used to transport the heat exchange liquid into the heat exchanger 5 to facilitate heat exchange between the heat exchanger 5 and the fluid flowing out of the combustion chamber. The liquid outlet pipe of the connecting pipe 4 is used to transport the liquid after heat exchange in the heat exchanger 5, thereby achieving circulation of the heat exchange liquid. In one embodiment, the heat exchange liquid is water.

[0119] like Figure 5 As shown, the flow of fluid in the ventilation interlayer 3, where the combustion chamber projection surface is Figure 2 In the projection surface along the direction of arrow B, in some embodiments, the fluid in the ventilation interlayer 3 is air. Of course, the fluid in the ventilation interlayer 3 can also be refrigerant, water or other fluids. This embodiment is described using air as an example.

[0120] The heat in the combustion chamber is transferred to the air in the ventilation interlayer 3 through the inner wall 1 of the combustion chamber, so that after the air in the ventilation interlayer 3 is heated, the heated air continues to move in the direction of air outflow in the ventilation interlayer 3, taking away some heat, causing the temperature of the air combustion chamber wall to change along the direction of air flow.

[0121] Take a rectangular combustion chamber as an example, where the combustion chamber inner wall 1 and the combustion chamber outer wall 2 are arranged in a "U" shape. A ventilation interlayer 3 is formed between the combustion chamber inner wall 1 and the combustion chamber outer wall 2. The thickness of the ventilation interlayer 3 is uniform. The length and width of the combustion chamber inner wall are a and b respectively, and the thickness of the ventilation interlayer is δ. The ratio of the interlayer air volume in the ventilation interlayer 3 to the total air volume is q x for:

[0122]

[0123] The air volume ratio is converted here into the ratio of the cross-sectional area of the air entering the channel:

[0124] The air volume entering the combustion chamber can be measured by the inner wall of the combustion chamber 1. Figure 2 The projection area S1 along the direction of arrow B is represented, where S1 = a*b;

[0125] The total air volume entering the combustion chamber can be calculated by the combustion chamber outer wall 2 Figure 2The projected area S along the direction of arrow B 总 Characterization, where

[0126] S 总 =(a+2δ)(b+2δ);

[0127]

[0128] From this we can see that the ratio of the interlayer air volume to the total air volume q x It is related to the thickness δ of the ventilation interlayer 3. By adjusting the thickness δ of the ventilation interlayer 3, the ratio q of the interlayer air volume to the total air volume can be easily adjusted. x .

[0129] Based on the simulation analysis, it is found that when other parameters remain unchanged, only the thickness of the ventilation interlayer 3 is changed to analyze the temperature of the surface monitoring point of the outer wall 2 of the combustion chamber. Figure 9 As shown, the thickness of the ventilation interlayer 3 is 0, indicating a coil-free heat exchange system with no interlayer air duct design. The combustion chamber inner wall 1 and the combustion chamber outer wall 2 are made of the same material, maintaining the total air volume constant. As the thickness of the ventilation interlayer 3 increases, the air volume entering the interlayer 3 increases, and the overall temperature of the combustion chamber wall surface gradually decreases. As the thickness of the ventilation interlayer 3 increases, the temperature drop gradually decreases.

[0130] Depend on Figure 9 It can be seen that the smaller the thickness of the ventilation interlayer 3, the greater the surface temperature T of the outer wall 2 of the combustion chamber, and the greater the thickness of the ventilation interlayer 3, the smaller the surface temperature T of the outer wall 2 of the combustion chamber; the air convects and exchanges heat in the ventilation interlayer 3, and if the thickness of the ventilation interlayer 3 is too small, the ratio of the inlet cross-sectional area of the ventilation interlayer 3 to the total inlet cross-sectional area is small, and the air flow rate entering the ventilation interlayer 3 is small, and the heat exchange in the flow heat exchange process is small, that is, the heat taken away is less, so the cooling effect on the combustion chamber wall is small, and the temperature requirements cannot be met.

[0131] Therefore, it is necessary to design a reasonable ventilation interlayer thickness to meet the combustion chamber outer surface temperature limit requirements of the heat exchange structure.

[0132] Based on the above analysis, in one embodiment, the relationship between the thickness δ of the ventilation interlayer 3 and the surface temperature T of the outer wall 2 of the combustion chamber satisfies the dimensionless formula:

[0133] T=K1-K2δ 2 +K3δ+δ(K4λ1+K5λ2)*10 -3 +K6λ1-K7λ1 2 -K8λ2+K9λ2 2 +K 10 λ1·λ2

[0134] Among them, K1=441~539, K2=2.907~3.553; K3=65.529~80.091; K4=1.89~2.31; K5=3.42~4.18; K6=0.342~0.418; K7=6.3*10 -4 ~7.7*10 -4 ; K8=0.126~0.154; K9=0.9*10 -4 ~1.1*10 -4 ;K 10 =1.8*10 -4 ~2.2*10 -4 ;

[0135] Where T represents the temperature value of the monitoring point on the outer wall 2 of the combustion chamber, in °C; δ is the thickness of the ventilation interlayer 3, in mm; λ1 is the thermal conductivity of the outer wall 2 of the combustion chamber, in W / (m·K); λ2 is the thermal conductivity of the inner wall 1 of the combustion chamber, in W / (m·K).

[0136] In one embodiment,

[0137] K1=490±4.41; K2=3.23±0.02907; K3=72.81±0.65529;

[0138] K4=2.1±0.0189; K5=3.8±0.0342; K6=0.38±0.00342;

[0139] K7=0.0007±0.00005; K8=0.14±0.00126;

[0140] K9=0.0001±0.00005; K 10 =0.0002±0.00005.

[0141] In one embodiment,

[0142] K1=490; K2=3.23; K3=72.81;

[0143] K4=2.1; K5=3.8; K6=0.38;

[0144] K7=0.0007; K8=0.14; K9=0.0001; K 10 =0.0002, at this time the relationship between the thickness δ of the ventilation interlayer 3 and the surface temperature T of the outer wall 2 of the combustion chamber satisfies:

[0145] T=490-3.23δ 2 +72.81δ+δ(2.1λ1+3.8λ2)*10 -3+0.38λ1-0.0007λ1 2 -0.14λ2+0.0001λ2 2 +0.0002λ1·λ2.

[0146] In this embodiment, through theoretical analysis and simulation calculation data analysis of different ventilation interlayer thicknesses, the upper side of the outer wall 2 of the combustion chamber close to the heat exchanger 5 is selected as the monitoring point to evaluate the surface temperature value. The temperature values of different ventilation layer thicknesses δ and different material compositions of the inner and outer sides of the combustion chamber (different thermal conductivity coefficients λ1 and λ2) under the same air volume are studied, and the relationship between the monitoring point temperature and the ventilation layer thickness is obtained.

[0147] The heat exchange structure associates the surface temperature T of the outer wall 2 of the combustion chamber with the thickness δ of the ventilation interlayer 3, so that the thickness setting range of the ventilation interlayer 3 can be determined by the set value of the surface temperature T of the outer wall 2 of the combustion chamber and the thermal conductivity coefficient of the inner wall 1 and the outer wall 2 of the combustion chamber. The thickness of the ventilation interlayer 3 can be set according to the characteristics of different materials, so that the designed thickness of the ventilation interlayer 3 matches the material characteristics. At the same time, the outer surface temperature of the combustion chamber of the external coil-free heat exchange structure can be reduced, effectively ensuring that the surface temperature T of the outer wall 2 of the combustion chamber can meet the external surface temperature limit requirements.

[0148] In the above embodiment, the fluid entering the combustion chamber mainly includes air and gas, wherein the air is divided into two parts. One part of the air is mixed with the gas and burns in the burner to form high-temperature flue gas. The high-temperature flue gas flows through the inner cavity of the combustion chamber and enters the heat exchanger 5 to exchange heat with the fluid in the heat exchanger 5; the other part of the air enters the ventilation interlayer 3 and exchanges heat with the inner wall 1 of the combustion chamber and the outer wall 2 of the combustion chamber in the interlayer channel of the ventilation interlayer 3. After the heat exchange, the air in the interlayer channel enters the heat exchanger 5 to exchange heat with the fluid in the heat exchanger 5. Among them, the air entering the combustion chamber is the total air volume; the air entering the inner cavity of the combustion chamber is the combustion air volume; the air entering the interlayer channel of the ventilation interlayer 3 is the interlayer air volume; and the total air volume is the sum of the combustion air volume and the interlayer air volume. When the total air volume remains unchanged, as the thickness of the ventilation interlayer 3 increases, the interlayer air volume gradually increases and the combustion air volume gradually decreases, which can effectively reduce the surface temperature T of the outer wall 2 of the combustion chamber.

[0149] In one embodiment, T≤250°C, the thickness δ of the ventilation interlayer 3 satisfies the dimensionless formula:

[0150] 3.23δ 2 -72.81δ-δ(2.1λ1+3.8λ2)*10 -3 -0.38λ1+0.0007λ1 2 +0.14λ2-0.0001λ2 2 -0.0002λ1·λ2≥240.

[0151] In one embodiment, T is the maximum temperature value of the surface monitoring point of the outer wall 2 of the combustion chamber. The maximum temperature value of the surface monitoring point of the outer wall 2 of the combustion chamber is selected as the surface temperature T of the outer wall 2 of the combustion chamber. The thickness δ of the ventilation interlayer 3 designed in this way can ensure that the surface temperature of the surface monitoring point of the outer wall 2 of the combustion chamber does not exceed the maximum temperature, effectively ensuring that the surface temperature T of the outer wall 2 of the combustion chamber meets the outer surface temperature limit requirement.

[0152] In one embodiment, T is the average temperature of the surface monitoring points on the outer wall 2 of the combustion chamber. Generally speaking, the temperature of the surface monitoring points on the outer wall 2 of the combustion chamber increases from bottom to top. Generally, the casing at the top of the combustion chamber cannot be touched, and only the casing in the middle of the combustion chamber can be touched. Therefore, as long as the temperature of the surface monitoring points on the outer wall 2 of the combustion chamber can be kept lower than the average temperature of the surface monitoring points on the outer wall 2 of the combustion chamber, the surface temperature T of the outer wall 2 of the combustion chamber can be guaranteed to meet the outer surface temperature limit requirement.

[0153] According to the actual product of the heat exchange structure, considering the heat transfer performance, high temperature resistance, corrosion resistance and other properties, the combustion chamber cavity is generally made of copper or stainless steel. The thermal conductivity of copper is 381W / (m·K), and the thermal conductivity of stainless steel is 16.72W / (m·K).

[0154] In this embodiment, the influence of the thickness δ of the ventilation interlayer 3 on the combustion chamber surface temperature and thermal efficiency is comprehensively considered, and then a combustion chamber structure is designed that meets both the combustion chamber surface temperature limit requirement and the thermal efficiency requirement.

[0155] In one embodiment, when η≥89.5%, T≤250°C;

[0156] When the outer wall 2 of the combustion chamber is made of copper and the inner wall 1 of the combustion chamber is made of copper, the thickness δ of the ventilation interlayer 3 satisfies 5.15mm≤δ≤8.8mm;

[0157] When the outer wall 2 of the combustion chamber is copper and the inner wall 1 of the combustion chamber is stainless steel, the thickness δ of the ventilation interlayer 3 satisfies 5.2mm≤δ≤8.8mm;

[0158] When the outer wall 2 of the combustion chamber is made of stainless steel and the inner wall 1 of the combustion chamber is made of stainless steel, the thickness δ of the ventilation interlayer 3 satisfies 4.17mm≤δ≤8.8mm;

[0159] When the outer wall 2 of the combustion chamber is made of stainless steel and the inner wall 1 of the combustion chamber is made of copper, the thickness δ of the ventilation interlayer 3 satisfies 3.52mm≤δ≤8.8mm.

[0160] In one embodiment, when η≥92.5%, T≤250°C;

[0161] When the outer wall 2 of the combustion chamber is made of copper and the inner wall 1 of the combustion chamber is made of copper, the thickness δ of the ventilation interlayer 3 satisfies 5.15mm≤δ≤5.4mm;

[0162] When the outer wall 2 of the combustion chamber is copper and the inner wall 1 of the combustion chamber is stainless steel, the thickness δ of the ventilation interlayer 3 satisfies 5.2mm≤δ≤5.4mm;

[0163] When the outer wall 2 of the combustion chamber is made of stainless steel and the inner wall 1 of the combustion chamber is made of stainless steel, the thickness δ of the ventilation interlayer 3 satisfies 4.17mm≤δ≤5.4mm;

[0164] When the outer wall 2 of the combustion chamber is made of stainless steel and the inner wall 1 of the combustion chamber is made of copper, the thickness δ of the ventilation interlayer 3 satisfies 3.52mm≤δ≤5.4mm.

[0165] By designing the above formula and selecting different thermal efficiencies η and surface temperatures T, the thickness δ of the ventilation interlayer 3 that meets the above thermal efficiency η and surface temperature T requirements can be calculated, which facilitates the design of the structure of the combustion chamber and ensures that the final processed heat exchange structure can meet the expected design requirements, achieve the required thermal efficiency and surface temperature, and improve the design efficiency of the heat exchange structure.

[0166] In one embodiment, the outer wall 2 of the combustion chamber and the inner wall 1 of the combustion chamber are both block structures, and the two are arranged in a one-to-one correspondence. The corresponding outer wall 2 of the combustion chamber and the inner wall 1 of the combustion chamber are fixedly connected together to form a ventilation interlayer 3. The ventilation interlayers 3 of different blocks are isolated from each other, and the individual ventilation interlayers 3 have an interlayer channel that passes through from top to bottom.

[0167] In this embodiment, the combustion chamber is a rectangular structure, and each side wall of the combustion chamber is composed of a block of the combustion chamber outer wall 2 and a block of the combustion chamber inner wall 1, wherein the block of the combustion chamber inner wall 1 is a rectangular plate, and flanges are respectively provided on two opposite sides of the rectangular plate. The two flanges abut the wall surface of the block of the combustion chamber outer wall 2 to form a rectangular ventilation interlayer 3. The two flanges extend in the vertical direction and are arranged in the horizontal direction on both sides of the block of the combustion chamber outer wall 1, thereby forming an interlayer channel that runs through from top to bottom. The two oppositely arranged blocks of the combustion chamber outer wall 2 are provided with flanges on both sides, and the flanges are buckled on the edges of the adjacent combustion chamber outer wall 2. Screw holes are provided on the flanges to facilitate the fixed connection of the two adjacent blocks of the combustion chamber outer wall 2 together.

[0168] In one embodiment, a connecting block 6 is provided between the combustion chamber inner wall 1 and the combustion chamber outer wall 2. One end of the connecting block 6 is fixedly connected to the combustion chamber inner wall 1, and the other end of the connecting block 6 is fixedly connected to the combustion chamber outer wall 2. The connecting block 6 defines the thickness δ of the ventilation interlayer 3. The fixed connection between the combustion chamber inner wall 1 and the combustion chamber outer wall 2 via the connecting block 6 can achieve a stable connection between the combustion chamber inner wall 1 and the combustion chamber outer wall 2, thereby ensuring the stability and reliability of the overall combustion chamber structure.

[0169] In one embodiment, the connecting block 6 is arranged on the inner wall 1 of the combustion chamber and protrudes from the inner wall 1 of the combustion chamber toward the outer wall 2 of the combustion chamber. A first connecting hole is provided at the vertex position of the protruding structure of the connecting block 6, and a second connecting hole is provided on the outer wall 2 of the combustion chamber corresponding to the first connecting hole. The outer wall 2 of the combustion chamber and the inner wall 1 of the combustion chamber are fixedly connected by screws provided in the first connecting hole and the second connecting hole.

[0170] In one embodiment, the connecting block 6 is a frustum and / or a cylinder, which can form an arc-shaped guide surface on the air flow path, reduce the flow resistance to the air flow, and improve the flow efficiency of the air flow in the ventilation interlayer 3.

[0171] In one embodiment, there are three connecting blocks 6 between the combustion chamber inner wall 1 and the combustion chamber outer wall 2 on each side, and the three connecting blocks 6 are arranged in a herringbone shape. In this embodiment, the three connecting blocks 6 are arranged in a herringbone shape, so that a more stable structural connection can be achieved with a smaller number of connecting blocks 6. Due to the smaller number of connecting blocks 6, the resistance to air flow is reduced, and the impact on airflow is reduced.

[0172] like Figures 6 and 7 As shown, in one embodiment, the cross section of the ventilation interlayer 3 is Figure 2 The cross section of the combustion chamber ventilation interlayer 3 at AA is a straight line, a curved line or a broken line. Figure 6 The second structural diagram of the ventilation interlayer of the heat exchange structure of the embodiment of the present invention is shown, that is, the cross section of the ventilation interlayer 3 is curved. Figure 7 The third structural diagram of the ventilation interlayer of the heat exchange structure of the embodiment of the present invention is shown, that is, the cross section of the ventilation interlayer 3 is a rectangular waveform.

[0173] Figure 5 For the combustion chamber Figure 2 The projection diagram along the B direction is preferably as follows: Figure 5 As shown in the first structural diagram of the ventilation interlayer of the heat exchange structure of an embodiment of the present invention, the cross section of the ventilation interlayer 3 is linear, the ventilation interlayer 3 includes multiple side portions, and the thickness of each side portion is the same. Figure 5The rectangular combustion chamber is formed by the combustion chamber inner wall 1 and the combustion chamber outer wall 2. The combustion chamber inner wall 1 has a first inner wall, a second inner wall, a third inner wall, and a fourth inner wall, which are sequentially connected to form the combustion chamber cavity; the combustion chamber outer wall 2 has a first outer wall, a second outer wall, a third outer wall, and a fourth outer wall, which are sequentially connected to form the outer side of the combustion chamber inner wall 1, forming a ventilation interlayer 3 between the combustion chamber inner wall 1. The first side portion of the ventilation interlayer is formed between the first inner wall and the first outer wall; the second side portion of the ventilation interlayer is formed between the second inner wall and the second outer wall; the third side portion of the ventilation interlayer is formed between the third inner wall and the third outer wall; and the fourth side portion of the ventilation interlayer is formed between the fourth inner wall and the fourth outer wall. The thickness of the first side portion of the ventilation interlayer, the thickness of the second side portion of the ventilation interlayer, the thickness of the third side portion of the ventilation interlayer, and the thickness of the fourth side portion of the ventilation interlayer are all the same.

[0174] As an alternative embodiment, the combustion chamber may also be hexagonal, octagonal, etc., which are not listed here one by one.

[0175] As an alternative embodiment, the combustion chamber can also be a circular combustion chamber, in which case the combustion chamber inner wall 1 has an inner wall, the combustion chamber outer wall 2 has an outer wall, and the ventilation interlayer 3 formed by the combustion chamber inner wall 1 and the combustion chamber outer wall 2 has a side portion, and the ventilation interlayer 3 has the same thickness.

[0176] As an alternative embodiment, Figure 8 As shown in the fourth structural diagram of the ventilation interlayer of the heat exchange structure according to an embodiment of the present invention, the cross-section of the ventilation interlayer 3 is linear, the ventilation interlayer 3 includes multiple side portions, and the thickness of the ventilation interlayer 3 varies on at least two side portions. When the structure of the ventilation interlayer 3 is any of the first to third structural diagrams, the thickness of at least two side portions may vary.

[0177] Specifically, in this embodiment, Figure 8 For the combustion chamber Figure 2In the projection diagram along the direction of arrow B, the rectangular combustion chamber is formed by the combustion chamber inner wall 1 and the combustion chamber outer wall 2. The combustion chamber inner wall 1 comprises a first inner wall, a second inner wall, a third inner wall, and a fourth inner wall, which are sequentially connected to form the combustion chamber cavity; the combustion chamber outer wall 2 comprises a first outer wall, a second outer wall, a third outer wall, and a fourth outer wall, which are sequentially connected to form the outer side of the combustion chamber inner wall 1, forming a ventilation interlayer 3 between the combustion chamber inner wall 1. The first inner wall and the first outer wall form the first side portion of the ventilation interlayer; the second inner wall and the second outer wall form the second side portion of the ventilation interlayer; the third inner wall and the third outer wall form the third side portion of the ventilation interlayer; and the fourth inner wall and the fourth outer wall form the fourth side portion of the ventilation interlayer. The thickness of the first side of the ventilated interlayer is the same as the thickness of the third side of the ventilated interlayer, and the thickness of the first side of the ventilated interlayer, the thickness of the second side of the ventilated interlayer, and the thickness of the fourth side of the ventilated interlayer are all different, that is, the thickness of three sides of the ventilated interlayer 3 is different.

[0178] Of course, as an alternative embodiment, the thickness of the first side of the ventilated interlayer is the same as the thickness of the second side of the ventilated interlayer, the thickness of the third side of the ventilated interlayer is the same as the thickness of the fourth side of the ventilated interlayer, and the thickness of the first side of the ventilated interlayer is different from the thickness of the third side of the ventilated interlayer.

[0179] As an alternative embodiment, the thickness of the first side of the ventilated interlayer is the same as the thickness of the second side of the ventilated interlayer and the thickness of the third side of the ventilated interlayer, and the thickness of the first side of the ventilated interlayer is different from the thickness of the fourth side of the ventilated interlayer.

[0180] As an alternative embodiment, there are other arrangements and combinations, as long as the thickness of at least two sides of the ventilation interlayer 3 are different, which are not listed here one by one.

[0181] According to an embodiment of the present invention, the heat exchange structure includes: an outer wall 1 of the combustion chamber, which forms a combustion chamber cavity; a combustion chamber outer wall 2, which is arranged on the outside of the combustion chamber outer wall 1 and forms a ventilation interlayer 3 between the combustion chamber inner wall 1, and the ventilation interlayer 3 has an interlayer channel; a heat exchanger 5, which is arranged downstream of the fluid flowing through the combustion chamber, and the fluid flowing out of the combustion chamber inner cavity exchanges heat with the liquid in the heat exchanger 5, and the interlayer channel is connected to the heat exchanger 5; the thickness δ of the ventilation interlayer 3 is T and the surface temperature of the combustion chamber outer wall 2 is T, and the ratio of the interlayer air volume to the total air volume is q x ;The thermal efficiency of the heat exchange structure is η;

[0182] When the outer wall 2 of the combustion chamber is copper and the inner wall 1 of the combustion chamber is copper, when η ≥ 89.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer 3 satisfies 5.15mm ≤ δ ≤ 8.8mm; when η ≥ 92.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer 3 satisfies 5.15mm ≤ δ ≤ 5.4mm;

[0183] When the outer wall 2 of the combustion chamber is copper and the inner wall 1 of the combustion chamber is stainless steel, when η ≥ 89.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer 3 satisfies 5.2mm ≤ δ ≤ 8.8mm; when η ≥ 92.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer 3 satisfies 5.2mm ≤ δ ≤ 5.4mm;

[0184] When the combustion chamber outer wall 2 is made of stainless steel and the combustion chamber inner wall 1 is made of stainless steel, when η ≥ 89.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer 3 satisfies 4.17mm ≤ δ ≤ 8.8mm; when η ≥ 92.5% and T ≤ 250°C, the thickness δ of the ventilation interlayer 3 satisfies 4.17mm ≤ δ ≤ 5.4mm;

[0185] When the outer wall 2 of the combustion chamber is stainless steel and the inner wall 1 of the combustion chamber is copper, when η≥89.5% and T≤250℃, the thickness δ of the ventilation interlayer 3 satisfies 3.52mm≤δ≤8.8mm; when η≥92.5% and T≤250℃, the thickness δ of the ventilation interlayer 3 satisfies 3.52mm≤δ≤5.4mm.

[0186] According to an embodiment of the present invention, the gas appliance includes a heat exchange structure, which is the above-mentioned heat exchange structure.

[0187] The gas appliance is, for example, a gas water heater or a wall-mounted boiler.

[0188] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0189] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0190] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A heat exchange structure, characterized in that: include: The inner wall (1) of the combustion chamber, the inner wall (1) of the combustion chamber enclosing the combustion chamber cavity; The combustion chamber outer wall (2) is arranged around the outer side of the combustion chamber inner wall (1) and forms a ventilation interlayer (3) with the combustion chamber inner wall (1), wherein the ventilation interlayer (3) has an interlayer channel; A heat exchanger (5) is provided downstream of the fluid flowing through the combustion chamber, the fluid flowing out of the inner cavity of the combustion chamber exchanges heat with the liquid in the heat exchanger (5), and the interlayer channel is connected to the heat exchanger (5); The relationship between the thickness δ of the ventilation interlayer (3) and the surface temperature T of the outer wall (2) of the combustion chamber satisfies the dimensionless formula: T=K1-K2δ 2 +K3δ+δ(K4λ1+K5λ2)*10 -3 +K6λ1-K7λ1 2 -K8λ2+K9λ2 2 +K 10 λ1·λ2 Among them, K1=441~539, K2=2.907~3.553; K3=65.529~80.091; K4=1.89~2.31; K5=3.42~4.18; K6=0.342~0.418; K7=6.3*10 -4 ~7.7*10 -4 ; K8=0.126~0.154; K9=0.9*10 -4 ~1.1*10 -4 ;K 10 =1.8*10 -4 ~2.2*10 -4 ; T represents the temperature value of the monitoring point on the surface of the outer wall (2) of the combustion chamber, in units of °C; δ represents the thickness of the ventilation interlayer (3), in units of mm; λ1 represents the thermal conductivity of the outer wall (2) of the combustion chamber, in units of W / (m·K); λ2 represents the thermal conductivity of the inner wall (1) of the combustion chamber, in units of W / (m·K); The ratio q of the interlayer air volume of the ventilation interlayer (3) to the total air volume x The relationship between the thickness δ of the ventilation interlayer (3) satisfies the dimensionless formula: Among them, r1=-0.412~-0.059; r2=0.042~0.369; r3=-18.598~-4.

924.

2. The heat exchange structure according to claim 1, characterized in that: K1=490±4.41; K2=3.23±0.02907; K3=72.81±0.65529; K4=2.1±0.0189; K5=3.8±0.0342; K6=0.38±0.00342; K7=0.0007±0.00005; K8=0.14±0.00126; K9=0.0001±0.00005;K 10 =0.0002±0.00005。 3. The heat exchange structure according to claim 1, characterized in that: K1=490; K2=3.23; K3=72.81; K4=2.1; K5=3.8; K6=0.38; K7=0.0007;K8=0.14;K9=0.0001;K 10 =0.0002。 4. The heat exchange structure according to claim 1, characterized in that: T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies the dimensionless formula:

5. The heat exchange structure according to claim 1, characterized in that: T is the maximum temperature value of the surface monitoring points of the outer wall (2) of the combustion chamber; or, T is the average temperature value of the surface monitoring points of the outer wall (2) of the combustion chamber.

6. The heat exchange structure according to claim 1, characterized in that: r1＝-0.21988±0.01545； r2＝0.19118±0.01443； r3＝-11.18943±0.57182。 7. The heat exchange structure according to claim 6, characterized in that: r1＝-0.21988； r2＝0.19118； r3＝-11.18943。 8. The heat exchange structure according to claim 1, characterized in that: The thermal efficiency η is determined by the ratio of the interlayer air volume to the total air volume q x Get; When the outer wall (2) of the combustion chamber is copper and the inner wall (1) of the combustion chamber is copper, when η≥89.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 5.15mm≤δ≤8.8mm; when η≥92.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 5.15mm≤δ≤5.4mm; When the outer wall (2) of the combustion chamber is copper and the inner wall (1) of the combustion chamber is stainless steel, when η≥89.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 5.2mm≤δ≤8.8mm; when η≥92.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 5.2mm≤δ≤5.4mm; When the combustion chamber outer wall (2) is made of stainless steel and the combustion chamber inner wall (1) is made of stainless steel, when η≥89.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 4.17mm≤δ≤8.8mm; when η≥92.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 4.17mm≤δ≤5.4mm; When the outer wall (2) of the combustion chamber is made of stainless steel and the inner wall (1) of the combustion chamber is made of copper, when η≥89.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 3.52mm≤δ≤8.8mm; when η≥92.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 3.52mm≤δ≤5.4mm.

9. The heat exchange structure according to any one of claims 1 to 8, characterized in that: The combustion chamber outer wall (2) and the combustion chamber outer wall (1) are both block structures, and the two are arranged in a one-to-one correspondence. The corresponding combustion chamber outer wall (2) and the combustion chamber inner wall (1) are fixedly connected together to form the ventilation interlayer (3). The ventilation interlayers (3) of different blocks are isolated from each other, and the individual ventilation interlayers (3) have an interlayer channel that passes through from top to bottom.

10. A heat exchange structure, characterized in that: include: The inner wall (1) of the combustion chamber, the inner wall (1) of the combustion chamber enclosing the combustion chamber cavity; The combustion chamber outer wall (2) is arranged around the outer side of the combustion chamber inner wall (1) and forms a ventilation interlayer (3) with the combustion chamber inner wall (1), wherein the ventilation interlayer (3) has an interlayer channel; A heat exchanger (5) is provided downstream of the fluid flowing through the combustion chamber, the fluid flowing out of the inner cavity of the combustion chamber exchanges heat with the liquid in the heat exchanger (5), and the interlayer channel is connected to the heat exchanger (5); The thickness δ of the ventilation interlayer (3) and the surface temperature of the outer wall (2) of the combustion chamber are T, and the ratio of the interlayer air volume to the total air volume is q x ; The thermal efficiency of the heat exchange structure is η; When the outer wall (2) of the combustion chamber is copper and the inner wall (1) of the combustion chamber is copper, when η≥89.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 5.15mm≤δ≤8.8mm; when η≥92.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 5.15mm≤δ≤5.4mm; When the outer wall (2) of the combustion chamber is copper and the inner wall (1) of the combustion chamber is stainless steel, when η≥89.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 5.2mm≤δ≤8.8mm; when η≥92.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 5.2mm≤δ≤5.4mm; When the combustion chamber outer wall (2) is made of stainless steel and the combustion chamber inner wall (1) is made of stainless steel, when η≥89.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 4.17mm≤δ≤8.8mm; when η≥92.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 4.17mm≤δ≤5.4mm; When the outer wall (2) of the combustion chamber is made of stainless steel and the inner wall (1) of the combustion chamber is made of copper, when η≥89.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 3.52mm≤δ≤8.8mm; when η≥92.5% and T≤250°C, the thickness δ of the ventilation interlayer (3) satisfies 3.52mm≤δ≤5.4mm.

11. A gas appliance comprising a heat exchange structure, characterized in that: The heat exchange structure is the heat exchange structure according to any one of claims 1 to 10.

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