JPS6138349A - Hot-water heating device - Google Patents

Abstract

PURPOSE:To reduce mixing in the hot-water heating device of push-up hot-water delivery system and permit to supply the hot-water of a given temperature for a longer period of time by designing the inner diameter of a water inlet pipe so that Gr/Re<2> becomes 0.05 or more. CONSTITUTION:The device is provided with a heating means 5 to heat a tank 1 from the lower layer thereof, the water inlet pipe communicated with the lower layer of the tank 1 and a water delivery pipe 7 communicated with the upper layer of the tank 1. The device is constituted so that the relation between a Reynolds number Re=ud/v, in which (u) means the average flow speed of fluid flowing into the water inlet pipe 6, (v) means the dynamic viscosity coefficient of the fluid and (d) represents the inner diameter of the water inlet pipe 6, and a Grashof number Gr=d<3>gbeta(TH-TL)/v, in which TL means the temperature of water flowing there-into through the water inlet pipe 6, TH means the temperature of hot-water in the upper layer of the tank, beta means the volumetric expantion coeffient, (g) means gravitational acceleration and (d) reprensents the inner diameter of the water inlet pipe, becomes Gr/Re<2>>=0.05. The configuration of the water inlet pipe or the like is constituted so as to suffice this condition and whereby the mixing may be reduced and the hot-water having a given temperature may be supplied for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hot water heating device that has means for heating from the lower layer of a tank and uses a push-up method.

Conventional configurations and problems Hot water heating devices that use a hot water pumping method are characterized by the ability to stably use hot water at a constant temperature stored in a tank. By the way, when this tank becomes smaller, or when the tank becomes thinner downwards, the phenomenon of mixing of hot water and water in the tank occurs more or less in such hot water heating devices. However, a problem has arisen in that the above characteristics cannot be fully utilized.

Purpose of the Invention The present invention solves such conventional problems by configuring a hot water heating device so that the parameter governing the mixing phenomenon of hot water and water in a tank has an appropriate value.
The purpose is to reduce mixing and supply hot water at a constant temperature for a longer period of time.

Structure of the Invention To achieve this objective, the present invention derives dimensionless parameters from the force of water flowing into the tank, the temperature difference between the positive and water inside the tank, etc., which governs the mixing phenomenon inside the tank, and Based on this value, the hot water heating device is configured so that the mixing level does not exceed a certain value.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The tank 1 is composed of a can body 2 and a lid 3 that are airtightly fixed.

A heater 4 is airtightly placed in the lid 3, and a heat generating part 5 of the heater 4 is located in the lower layer of the tank 1. On the lid 3,
A water inlet pipe 6 and a hot water outlet pipe 7 are attached, and the water outlet 8 of the water inlet pipe 6 is provided in the lower layer of the tank 1, and the large intestine port 9 of the hot water outlet pipe 7 is provided in the upper layer of the tank 1''.

Also, on the side of the can body 2, there is a thermistor 1 for controlling the storage i.
0 is installation. A signal from the thermistor 10 is input to a temperature control section 11, which controls electrical input to the heater 4 so that the stored hot water temperature reaches a set temperature.

Now, the factors governing the mixing phenomenon of the intestines and water in tank 1 are forced convection represented by the water flowing in from inlet pipe 6, and natural convection caused by the temperature difference between the hot water and water in tank 1. , the former forced convection works to promote mixing, and the latter natural convection works to suppress mixing. The parameters representing the strength of forced convection are the inner diameter d of the water inlet pipe 6, the average flow velocity u of the water flowing out from the water outlet 8 of the water inlet pipe 6, and the Reynolds number ReRe determined by the kinematic viscosity coefficient ν of the water.
= u d /ν.

In addition, the parameters indicating the strength of natural convection are: TL is the temperature of the water flowing in from the water inlet pipe 6, TH is the temperature of the hot water in the upper layer of the tank 1, β is the body expansion coefficient of water, g is the gravitational acceleration,
Grashof number Gr=d3gβ(TH-TL)/ν where the inner diameter d of is the representative length.

According to the flow similarity law when natural convection and forced convection coexist, if Gr/Re2 is equal, these flows will be similar. Therefore, the mixing phenomenon of water and intestines caused by the flow (forced convection) of water flowing in from the water inlet pipe 6 is expressed by G r /Re 2, which is a dimensionless parameter. Among the parameters G r /Re 2, parameters that can be optimized in terms of design are the inner diameter d of the water inlet pipe 6 and the average flow velocity U of water flowing out from the water outlet 8 of the water inlet pipe 6. Therefore, this time, the degree of mixing between hot water and water was measured by changing the inner diameter d of the water inlet pipe 6. Fig. 2 shows the arrangement using the parameters G r / Re 2. Here, the degree of mixing indicates the ratio of the mixed layer formed by mixing hot water and water to the volume of the tank 1.

It was found that when the value of G r /Re 2 was 0.05, the mixing and mixing degree increased significantly and the function as a hot water storage tank was impaired.

Therefore, in this embodiment, the inner diameter d of the inlet pipe 6 is set so that G r /Re 2 is equal to or greater than 0.05. The inner diameter d of the water inlet pipe 6 is determined by the parameter Gr/
Since it becomes effective at the fifth power at Re2, the effect is large.

By increasing the inner diameter d of the water inlet pipe 6, G
Although r/Re 2≧0.05 can be satisfied, the effective amount of hot water stored in the tank 1 will be reduced by the volume of the water inlet pipe 6.

Next, a second embodiment will be explained using FIG. 3.

In the figure, the same parts as in the first embodiment are given the same numbers. In this embodiment, the inner diameter of the water inlet pipe 6A increases as it reaches the water outlet 88. The water flowing into the water inlet pipe 6A reduces its flow velocity as the flow path expands and reaches the water outlet 8. With such a configuration, it is possible to effectively reduce the
It has the same effect as if the inner diameter d of A was substantially expanded, and the inner diameter at the water outlet 8A can be taken as the representative length. Furthermore, the influence of the volume of the water inlet pipe 6 on the effective hot water storage capacity of the tank 1 is also reduced.

In this embodiment, the angle of expansion into the inlet pipe 6 is preferably within 15 degrees to prevent the flow from separating from the pipe wall.

A third embodiment will be described using FIG. 4. In the figure,
The same parts as in the first embodiment are given the same numbers. In this embodiment, a rapidly expanding portion 12 is formed integrally with the water outlet 8B of the water inlet pipe 6B, and a resistor 13 is provided at the tip of this rapidly expanding portion 11. In this embodiment, although the fluid resistance increases compared to the second embodiment, the flow can be reliably expanded, and the typical length of the water inlet pipe 6B can be set to the inner diameter of the rapidly expanding portion 12. can. Further, the influence of the volume of the water inlet pipe 6B on the effective hot water storage amount of the tank 1 can be sufficiently reduced.

As described in detail, the hot water heating device according to the present invention can reduce the effects of heating.

The problem of mixing intestines and water in a tank can be solved by a parameter G r /
By experimenting to find a limit that would keep the mixing of Re 2 sufficiently small, and configuring the shape of the inlet pipe to meet this condition, mixing was reduced and hot water at a constant temperature could be supplied for a long time. .

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view of a hot water heating device showing one embodiment of the present invention, Fig. 2 is an explanatory diagram showing the characteristics of the hot water heating device, and Fig. 3 is a second embodiment of the hot water heating device according to the present invention. FIG. 4 is a partial sectional view showing a third embodiment of the hot water heating device according to the present invention. 1...Tank, 5...Heating part (heating means), 6.6A, 6B...Water pipe, 7...
... Hot water pipe, 12 ... Rapidly expanding part, 13 ...
...Resistor. Figure 1 Figure 2 ρ 4ρ5 θ, /6 q/6 θ12ρθP/R
e2 Figure 3 Figure 4

Claims (3)

[Claims] (1) It has a means for heating from the lower layer of the tank, an inlet pipe communicating with the lower layer of the tank, and an outlet pipe communicating with the upper layer of the tank, and the average flow velocity of the fluid flowing in from the water inlet pipe is u, The kinematic viscosity coefficient is ν, the inner diameter d of the water inlet pipe is the representative length, the Reynolds number Re Re = ud/ν, the temperature of the water flowing from the water inlet pipe is TL, and the temperature of the hot water in the upper layer of the tank is TH. , the body expansion coefficient is β, the gravitational acceleration is g, and the inner diameter d of the water inlet pipe is the representative length. Hot water heating device. (2) The hot water heating device according to claim 1, wherein the inner diameter of the water inlet pipe is gradually expanded toward the lower layer of the tank. (3) The water inlet pipe has a rapidly expanding part in the lower layer of the tank,
The hot water heating device according to claim 1, wherein a resistor is provided at the tip of the rapidly expanding portion.