JPS60249A - Heat exchanger - Google Patents

Abstract

PURPOSE:To miniaturize the heat exchanger by a method wherein gas area in the heat exchanger for hot-water supplying is decreased to increase the rate of two-phase area and use the heat exchanger in the high area of heat exchanging efficiency. CONSTITUTION:A branch tube 9, provided at the heat source side fluid entrance 10 of the heat exchanger 21, is connected to an intermediate entrance port 12 on the way of a main circuit a b c d e. High temperature high pressure superheated gas, discharged from a compressor 1, is branched at the entrance 10 and the main stream of the gas flows into the main circuit to dissipate the heat to water side and is condensed, while a branched stream, passing through the branch tube 9, flows into the main circuit through the hole 12 in the form of the superheated gas as it is and increases the drying degree of the condensed main stream as well as the heat transmission of the heat source fluid after joining of the flow. The main stream after branching decreases the amount of heat dissipation in the superheated gas area in accordance with the decrease of the flow amount thereof, therefore, it begins to condense quickly and the area of large heat transmitting rate is maintained whereby necessary pipe length may be shortened and the heat exchanger may be miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a heat exchanger for heating feed water in a water heater using a heat pump cycle.

Conventional structure and its problems Conventionally, in a heat pump water heater that heats and raises the temperature of water using the condensation heat of the heat pump cycle, as shown in FIG. The heating device 4 and the accumulator 6 are successively connected through refrigerant piping to form a sealed circuit. 6 is a hot water storage tank, 7 is a water supply pipe, and 8 is a hot water outlet pipe.

Here, the high-temperature, high-pressure superheated gas refrigerant discharged from the compressor 1 radiates heat to the water side of the hot water storage tank 6 in the hot water heat exchanger 2 inserted into the hot water storage tank 6 and condenses, resulting in gas and two-phase situation,
It changes phase with liquid and flows out as liquid refrigerant. In this heat exchange process, the gas refrigerant region occupies a relatively large proportion of the total pipe length of the hot water supply heat exchanger 2 even though the amount of heat radiated is small, so the hot water supply heat exchanger 2 becomes large. On the other hand, when there is a restriction in the installation space of the hot water supply heat exchanger 2, the disadvantage is that the temperature of the boiling water in the hot water storage tank 6 becomes low. This will be explained in detail with reference to FIGS. 2, 3, and 4.

The heat radiation amount of each region of the refrigerant in the hot water supply heat exchanger 6 is the refrigerant circulation amount G
R and enthalpy difference Δ1 (gas region ΔiG two-phase region lip
It is expressed as the product of the liquid region ΔiL), and in practical terms, it is about gas region: two-phase region: liquid region ζ0.1e: 0.8: 0.04, and the amount of heat dissipated in the gas region is about 16% of the total. .

On the other hand, the pipe length ratio of each refrigerant region in the hot water supply heat exchanger 2 is different in the heat transfer coefficient on the refrigerant side in the liquid region A, two-phase region B, and gas region C in Fig. 4, and the two-phase region is the best. , gas region C
Since the installation A is much smaller than the two-phase region B, the heat release ratio of each region does not match, and as shown in Fig. 3, the gas region LG:
Two-phase region LP: liquid region LL'=0.32: 0.6
: Approximately 0.08, and the gas area LG is approximately 32 of the total pipe length.
%. As described above, the gas region LG requires a large pipe length ratio compared to its heat dissipation amount, which has been an obstacle to downsizing the heat exchanger. Note that the dashed-dotted line in FIG. 3 is an equimixture line.

Purpose of the Invention The present invention solves the above-mentioned conventional problems by reducing the gas region in a heat exchanger for hot water supply and increasing the two-phase region ratio to use it in an area with high heat exchange efficiency. By this,
The purpose is to downsize heat exchangers.

Structure of the Invention In the present invention, a branch pipe is provided at the fluid inlet on the heat source side, one of the branch pipes forms a heat source side fluid main circuit spanning the entire pipe length, and the other branch pipe forms an intermediate inlet provided in the middle of this main circuit. This configuration reduces the flow rate flowing in from the inlet of the main circuit to reduce the gas area in the main circuit, and connects the intermediate inlet hole to the gas area in the main circuit where it condenses into a two-phase state. By mixing superheated gas and instantly turning it into a two-phase state, the overall gas region ratio can be reduced, and by using regions with high heat exchange efficiency, the heat exchanger can be made smaller. DESCRIPTION OF EMBODIMENTS OF THE INVENTION An embodiment of the present invention will be described in FIG. Incidentally, the same parts as in the conventional example are given the same numbers and explanations are omitted.

9 is a branch pipe provided at the heat source side fluid inlet portion 1° of the hot water heat exchanger 21; 11 is a flow rate adjustment unit arranged in series with the branch pipe 9;
12 is the main circuit of the hot water heat exchanger 21 (a-+b-+c
-+ d -) This is an intermediate inlet hole provided in the middle of e), and the branch pipe 9 is connected to the intermediate inlet hole 12.

In this circuit configuration, a case will be explained in which fluorocarbons are used as the heat source fluid and water as the fluid to be heated is heated and heated by a heat pump cycle. The fluid is separated at the heat source side fluid inlet 10, the main flow flows into the main circuit, radiates heat to the water side and condenses, and the branched flow passing through the branch pipe 9 flows into the main circuit through the intermediate inlet hole 12 as superheated gas, It increases the dryness of the already condensed mainstream and increases the heat transfer of the heat source fluid after merging. FIG. 6 shows the phase change state of the heat source fluid in the hot water supply heat exchanger described above, where the solid line is for this embodiment and the broken line is for the conventional case. The amount of heat dissipated in the superheated gas region of the main stream after the branch flow decreases as the flow rate decreases, so it starts condensing earlier than in the conventional case, and as the branch streams merge, its dryness increases and the heat transfer coefficient decreases. Large areas are maintained. Therefore, the required pipe length of the heat exchanger is Ll, which is shorter than the pipe length L2 in the conventional system.

In this way, the heat exchanger for hot water supply can fully utilize the two-phase region where the heat transfer coefficient on the heat source fluid side is high, so the heat transfer coefficient K of the heat exchanger can be increased. Therefore, the heat exchanger can be made smaller.

Also, if the size of the heat exchanger remains the same as before, the heat exchange amount Q will increase by the improvement in the heat transfer rate, but if the heat exchange amount Q is constant, the heating side fluid and the heated side fluid The temperature difference ΔT can be reduced. In other words, the water temperature in the hot water storage tank 6 can be made much higher.

Furthermore, due to the simple configuration of the branch pipe 9 and the intermediate inlet hole 12, improved performance can be achieved at low cost.

Moreover, by arranging the flow rate adjustment unit 11 in series with the branch pipe 9 to control the flow rate flowing through the branch pipe, not only can heat exchange be promoted more efficiently, but also the circulation amount of the heat source side fluid and the flow rate at the inlet can be improved. It becomes possible to adapt to a wide range of conditions in response to changes in superheated gas conditions.

Effects of the Invention The heat exchanger of the present invention is provided with a branch pipe at the fluid inlet on the heat source side,
One side forms a heat source side fluid main circuit that spans the entire pipe length, and the other branch pipe is connected to an intermediate inlet hole provided in the middle of this main circuit, and the heat is radiated by the condensed phase change of the heat source side fluid to the heated side. Since the fluid is heated, the proportion of the gas region is reduced, and the heat exchange efficiency is high.Since the two-phase region is utilized, the heat transfer rate K of the heat exchanger is large, and the heat exchanger can be made smaller.

2. Since the heat transfer coefficient K is large, hot water can be boiled to a high temperature.

3. Low cost due to simple structure.

The effect is profound.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional heat pump water heater, Figure 2 is a pressure-enthalpy diagram showing a heat cycle pump, Figure 3 is an explanatory diagram of state changes in a heat exchanger for hot water supply, and Figure 4 is a phase change. Heat transfer characteristic diagrams in each region, Figure 5 is a configuration diagram of a heat pump water heater using a heat exchanger according to an embodiment of the present invention, and Figure 6 is a phase change state in a heat exchanger according to an embodiment of the present invention. It is an explanatory diagram. DESCRIPTION OF SYMBOLS 1... Compressor, 2, 21... Hot water supply heat exchanger, 9... Branch pipe, 11... Flow rate adjustment section, 12... ...Intermediate entrance hole. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 3 Shoulder cough -) 8 Figure 5 Figure 6 Population Director L

Claims (2)

[Claims] (1) A branch pipe is provided at the fluid inlet on the heat source side, one of the branch pipes forms a heat source side fluid main circuit spanning the entire pipe length, and the other branch pipe is connected to an intermediate inlet hole provided in the middle of this main circuit. ,
A heat exchanger configured to radiate heat through a condensed phase change of the fluid on the heat source side and heat the fluid on the heated side. (2) The heat exchanger according to claim 1, wherein the flow rate adjustment section is provided in series with the branch pipe.