JP5145975B2 - Fluid heating device - Google Patents

Description

  The present invention relates to a fluid heating apparatus suitable for a device for heating air such as an electric hot air fan, an air conditioner, and a dryer.

  Conventionally, this type of fluid heating apparatus generally conducts and transfers heat from an electric heater such as a sheathed heater to a plate fin and transfers convection heat to ambient air sent by a blower or the like (for example, , See Patent Document 1 and Patent Document 2).

In order to improve thermal conductivity, the outer shell of the electric heater and the plate fin are usually formed of aluminum.
Japanese Utility Model Publication No. 62-42469 JP-A-6-231873

  However, in the above-described conventional configuration, when the flow amount of a load fluid, for example, air, fluctuates, specifically, when the air flow amount is controlled by so-called ON-OFF control for temperature adjustment, the electric heater The operating temperature cannot be increased due to the heat resistance of the outer shell and plate fin.

  That is, when the amount of air flow is reduced or the flow is stopped, so-called low load, the outer shell of the electric heater and the plate fin become abnormally high temperature and melt.

  Therefore, conventionally, a high-temperature electric heater cannot be used, and the fluid heating device is limited to a low output, and the thermal efficiency is not sufficient.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a fluid heating apparatus having excellent heat resistance, high efficiency, and high output.

In order to solve the above-mentioned conventional problems, the fluid heating device of the present invention includes a plurality of plate fins arranged in parallel and formed of surface-polished aluminum or copper, and through holes provided in the plate fins. A heat transfer pipe formed of aluminum or copper subjected to surface polishing treatment, which is penetrated and held tightly, and an electric heater having a round bar shape inserted into the heat transfer pipe, the heat transfer pipe and the electric heater A gap serving as an air layer is provided between the two.
The fluid heating device according to the present invention includes a plurality of plate fins arranged side by side with a surface treatment for reducing the emissivity, and an emissivity that is tightly held by penetrating through a through hole provided in the plate fin. A heat transfer pipe that has been subjected to a surface treatment for lowering the temperature and an electric heater having a round bar shape inserted into the heat transfer pipe, and a gap that forms an air layer between the heat transfer pipe and the electric heater. And the emissivities of the plate fins and the heat transfer pipe are set lower than the outer material of the electric heater.

The air layer in the gap exhibits a heat buffering action, and therefore, even if the fluid to be heated, that is, the load, fluctuates, rapid temperature fluctuations of the heat transfer pipe and the plate fin can be suppressed. In this case, particularly the plate fin and the heat transfer pipe are processed to reduce the emissivity, so that useless heat dissipated as radiant heat can be reduced as much as possible, and heat can be effectively transferred to the fluid.

  According to the fluid heating device of the present invention, even if the load to be heated fluctuates due to the air layer in the gap exerting a thermal buffering action, rapid temperature fluctuations of the heat transfer pipe and the plate fin can be prevented.

  Therefore, aluminum having excellent thermal conductivity can be used for the heat transfer pipe and the plate fin, and as a result, high output and high efficiency of the apparatus can be achieved.

Fluid heating apparatus of the present invention, the surface polished aluminum or a large number of plate fins arranged in parallel and formed of copper, is penetrated into the through hole tightly held surface polishing treatment provided in the plate fins A heat transfer pipe formed of aluminum or copper and a round bar-shaped electric heater inserted into the heat transfer pipe, and a gap serving as an air layer between the heat transfer pipe and the electric heater. Is provided.

Therefore, the air layer in the gap exhibits a thermal buffering effect, and even if the load such as the fluid to be heated fluctuates, rapid temperature fluctuations of the heat transfer pipe and the plate fin can be suppressed. In this case, in particular, the plate fin and the heat transfer pipe are formed of surface-polished aluminum or copper, and since the emissivity is low, wasteful heat dissipated as radiant heat can be reduced as much as possible, and heat can be effectively transferred to the fluid. .

In addition, a large number of plate fins arranged side by side with a surface treatment for lowering the emissivity, and a surface treatment for lowering the emissivity of the plate fins penetrating through the through holes provided in the plate fins . A heat transfer pipe and a round bar-shaped electric heater inserted into the heat transfer pipe. A gap serving as an air layer is provided between the heat transfer pipe and the electric heater, and a plate fin and a heat transfer pipe are provided. The emissivity of the heat pipe was set lower than the outer material of the electric heater.

According to this configuration, it is possible to suppress sudden temperature fluctuations of the heat transfer pipe and the plate fin, and of course, since the emissivity of the plate fin and the heat transfer pipe is low, wasteful heat dissipated as radiant heat can be reduced as much as possible. Heat can be effectively transferred to the fluid.

  It is conceivable to employ a sheathed heater as the electric heater.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below do not limit the present invention.

(Embodiment 1)
In the figure, a large number of plate fins 1 are arranged side by side to form one fin block 2, and an electric heater 3 comprising a sheathed heater is inserted into the fin block 2 in a meandering manner.

  The fin block 2 is disposed, for example, facing the ventilation path of the hot air heater, and when the air flowing through the ventilation path passes through the gap between the plate fins 1, it is heated by an action such as convection. It will be warmed.

  The details of the insertion configuration of the electric heater 3 with respect to the fin block 2 are as shown in FIG. 2, and actually, the electric heater 3 is installed in the heat transfer pipe 4 with a gap t serving as an air layer. On the outside of 2, the electric heater 3 is connected in a U-shape, and this is set in a meandering shape.

  The electric heater 3 has a so-called sheathed heater structure in which a heating wire 6 is passed through the center of an iron-based heater pipe 5 and a heat conductive material 7 is filled in a gap between the two.

  Further, the heat transfer pipe 4 and the plate fin 1 are formed of a heat conducting material such as aluminum.

  In the above configuration, first, the heating wire 6 generates heat by energization, and the heat is transmitted to the heater pipe 5 through the electrical insulating material 7, and is radiated as radiant energy, and reaches the heat transfer pipe 4 through the gap t.

  As a result, the heat transfer pipe 4 is heated by the absorbed radiant energy and then transmitted to the plate fins 1 by conduction.

  Therefore, as described above, if the fin block 2 is arranged facing the ventilation path of the warm air heater, when the air flowing through the ventilation path passes through the gap between the plate fins 1, It is heated and warmed by the action of convection.

  Here, the significance of installing the electric heater 3 in the heat transfer pipe 4 with a gap t serving as an air layer will be described.

  For example, in a warm air heater, a constant amount of air does not always flow through the ventilation path. That is, the load applied to the electric heater 3 changes every moment. That is, the load fluctuates linearly or intermittently on and off in relation to the set temperature of heating, and the output of the electric heater 3 needs to be controlled accordingly.

  However, it is theoretically difficult to perfectly synchronize the fluctuation of the air amount and the output control of the electric heater 3, and in particular, when the load suddenly fluctuates in a small direction, the temperature of the electric heater 3 reaches a value close to an abnormal value. It will rise.

  In general, since the plate fin is made of aluminum, which is a heat conducting material, it can be understood that a high output cannot be used as the electric heater 3 in view of its heat resistance.

  However, if the heat transfer pipe 4 is provided outside the electric heater 3 with a gap t as in the present embodiment, the air layer in the gap t exhibits a thermal buffering effect, and the temperature of the electric heater 3 is increased. It will absorb changes.

  As a result, even when a heat conducting material such as aluminum is used for the heat transfer pipe 4 and the plate fin 1, they do not reach an abnormally high temperature and do not become an obstacle to heat resistance.

  From the above, the efficiency as the fluid heating device is improved, and in addition, high output can be achieved, and high durability can be obtained.

(Embodiment 2)
The configuration of the second embodiment is basically the same as that of the first embodiment.

  The difference is that the emissivities of the plate fin 1 and the heat transfer pipe 4 are reduced. That is, the generation of radiant heat is suppressed as much as possible.

  For example, in a hot air heater, heating of air as a load is mostly convection due to the heat of the plate fins 1, and radiant heat does not contribute to air heating.

  Table 1 shows the emissivity for each metal material.

  As shown in Table 1, aluminum, copper, silver, and the like are suitable as materials. However, in consideration of cost, it is appropriate to employ aluminum or copper.

  In addition, since the emissivity decreases as the surface is polished even with the same material, it is advantageous to perform surface treatment for polishing the surfaces of aluminum and copper.

  By adopting aluminum or copper having a low emissivity in the surface treatment, the emissivity becomes about 0.1, so that most of the thermal energy Q generated by the electric heater 3 becomes convective heat transfer energy Qc, and the heat of the electric heater 3 Energy can be used to efficiently warm the surrounding air.

  Here, when the heat energy Q is expressed by a simple theoretical formula, the sum of the radiant energy Qr = A × ε × (Tw4−To4) and the convective heat transfer energy Qc = A × h × (Tw−To) Q = Qr + Qc It becomes.

  Here, A is the surface area of the heat source, ε is the emissivity, Tw is the surface temperature of the electric heater, To is the ambient temperature, and h is the heat transfer coefficient of air. As can be seen from this equation, when the emissivity ε increases, the influence of the radiation energy calculated by the fourth power of the temperature increases.

  In the above-described embodiment, the case where air is used as the load has been described.

  The fluid heating device according to the present invention can prevent a sudden temperature fluctuation of the heat transfer pipe and the plate fin even if the load to be heated fluctuates due to the air layer in the gap exerting a thermal buffering effect, and the heat conductivity is improved. Excellent aluminum can be used for heat transfer pipes and plate fins. As a result, it is possible to increase the output and efficiency of the equipment, and use it for heaters and dryers that use hot air as a heat source. Is possible.

1 is a schematic perspective view of a fluid heating apparatus according to Embodiment 1 of the present invention. Partial sectional view of the same Enlarged sectional view of the main part

Explanation of symbols

1 plate fin 3 electric heater 4 heat transfer pipe t gap

Claims (3)

A large number of plate fins arranged side by side made of surface-polished aluminum or copper ;
A heat transfer pipe formed of aluminum or copper that has been surface-polished and passed through a through-hole provided in the plate fin and is held tightly;
An electric heater having a round bar shape inserted into the heat transfer pipe,
A fluid heating apparatus in which a gap serving as an air layer is provided between the heat transfer pipe and the electric heater. And large number of plate fins arranged in parallel with a surface treatment to lower the emissivity,
A heat transfer pipe that has been subjected to a surface treatment to reduce the emissivity that is penetrated through the through-hole provided in the plate fin and held tightly;
An electric heater having a round bar shape inserted into the heat transfer pipe,
A fluid heating apparatus in which a gap serving as an air layer is provided between the heat transfer pipe and the electric heater, and emissivities of the plate fin and the heat transfer pipe are set lower than the outer material of the electric heater. The fluid heating apparatus according to claim 1, wherein the electric heater is a sheathed heater.