JPS59200163A - Heat exchanger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] This invention relates to a heat exchanger used in liquefiers, refrigerators, etc.

[Prior art and its problems] The principle of a low-temperature liquefaction machine is shown in Figure 1. Compressor (1
), the gas is compressed to high temperature and high pressure and is then transferred to a heat exchanger (2).
) flows into the high temperature flow path. Here, the low-temperature, low-pressure gas returning from the liquid storage container (3) to the compressor (1) flows into the low-temperature flow path of the heat exchanger (2), where it exchanges heat with the high-temperature, high-pressure gas. Cools high-temperature, high-pressure gas to below the reversal temperature. This cooled high-pressure gas is transferred to the Joule-Thompson valve (hereinafter referred to as JT valve) (4).
The liquid is further cooled by Thomson expansion, and a portion of the liquid is liquefied and stored in the liquid storage container (3). The remaining cooled gas flows into the low-temperature flow path of the heat exchanger (2) and exchanges heat with the above-mentioned high-temperature, high-pressure gas, cools this high-pressure gas to below the reversal temperature, and sends it to the compressor (1). return. The gas returned to the compressor (1) is compressed again and the above steps are repeated.

In general, the higher the heat exchange rate of the heat exchanger (2), the more J
Since the temperature at the inlet of the T valve (4) is lowered, the liquefaction rate and refrigeration efficiency due to Ziehl-Thompson expansion of the JT valve (4) are improved. However, when liquefying helium to generate the following superfluid helium at lambda point 2.17, the temperature at the inlet of JT valve (4) may drop below the lambda point. When the temperature at the inlet becomes below the lambda point, helium f's enters a superfluid state, and in the superfluid state there is almost no viscosity. Therefore, a large amount of the superfluid component of helium does not pass through the JT valve (4), and the superfluid helium is rapidly stored in the liquid storage container (4) and evaporates into the heat exchanger (2). Gas rapidly decreases, and the heat exchanger (2)'s capacity decreases. Then, this time, the JT valve (
4) will increase, and the superfluid helium stored in the liquid storage container (3) will rapidly decrease (this will make cooling extremely unstable. If the temperature at the inlet is too high, efficiency such as liquefaction rate will decrease.

Therefore, it is necessary to design and manufacture the heat exchanger (2) so that the temperature at the inlet of the JT valve (4) reaches a temperature above the lambda point near the lambda point, but the heat exchange efficiency of the heat exchanger It has been extremely difficult to design and manufacture a heat exchanger with appropriate heat exchange efficiency because it changes depending on the flow rate and also changes over time due to dirt in the flow path.

[Object of the Invention] An object of the present invention is to provide a heat exchanger that eliminates the above-mentioned drawbacks and can obtain appropriate heat exchange efficiency by controlling the heat exchange temperature.

[Summary of the Invention] The present invention provides a heat exchanger in which a heater is provided near a flow path for heat exchange, and the temperature of heat exchange can be controlled by changing the current flowing through the heater. It is in.

[Effects of the Invention] According to the present invention, the temperature at the outlet of the high-temperature flow path of the heat exchanger is designed to be lower than a predetermined temperature, and the energizing current of the heater of the heat exchanger is controlled. Since the temperature at the outlet of the high-temperature flow path can be controlled to a predetermined temperature, if this heat exchanger is used in a cooling device that cools down to below the lambda point, such as a superfluid helium generator, the efficiency of the cooling device can be improved. improves.

[Embodiments of the Invention] Representative embodiments of the present invention will be described with reference to the drawings. Second
The figure is a schematic configuration diagram of a heat exchanger according to the present invention. low temperature,
A coil-shaped high temperature flow path (6) through which high temperature and high pressure gas flows is housed within the low temperature flow path (5) through which low pressure gas flows. The heater (7) is wrapped around the outer periphery of the low temperature flow path (5). Low-temperature, low-pressure gas flows in from the low-temperature channel inlet (8) and flows out from the low-temperature channel outlet (9). It flows out from the road exit a1).

Next, the operation will be explained.

When the high-temperature high-pressure gas flowing into the heat exchanger from the high-temperature channel inlet (10) flows through the coil-shaped high-mixing channel (6), it flows from the low-temperature channel inlet (8) to the low-temperature channel (5). ) The high-pressure gas is cooled by heat exchange with the low-temperature low-pressure gas flowing into the high-pressure gas. The high-pressure gas flows out from the high-pressure side outlet (11!), and the low-pressure gas flows out from the low-temperature flow path outlet (9).If the heat exchanger in Figure 2 corresponds to the one in Figure 1, the low-temperature flow path will flow out. The passage (9) is connected to the compressor (1), and the high temperature flow passage outlet (lυ) is connected to the JT valve (4).Then, by changing the current flowing through the heater (7), high temperature high pressure gas and The temperature of heat exchange with low-temperature low-pressure gas can be changed, and this temperature-controlled high-pressure gas flows out from the high-temperature flow path outlet α1).
It will flow into valve (4).

In Fig. 2, the heater (7) is wrapped around the outer wall of the low-temperature flow path (5) through which low-temperature, low-pressure gas flows, but it may also be wrapped around the inner wall of the low-temperature flow path (5). It may be wrapped around the flow path (6).

Next, FIG. 3 shows a Calorie superfluid helium refrigerator using a heat exchanger according to the present invention. This pressurized superfluid hem/ram is stored in a HeI tank α3) in which liquid is stored in a vacuum vessel of 4.2 times, and objects to be cooled such as superconducting coils fJ5.
1 If is immersed in a superfluid state of 1.8
fJ (Equipped with a He1l tank for storing liquid. He
[Helium tank (1 (8)) is supplied with liquid from helium refrigerator (2) to 4.2. He1 tank 03 and Hei tank α are connected by a thin connecting tube α6). connected,
This field block α6) is equipped with a safety valve aη01.
4) Reduces heat infiltration. Furthermore, Hel[N (
14) In order to cool the liquid helium in the Hel tank (
I3) Joule-Thomson heat exchanger σ8) (hereinafter referred to as JT heat exchanger) to further cool the liquid helium flowing out from the internal force to a temperature that allows Ziehl-Thomson expansion.
, JT valve Qgl and heat exchanger valve, JT
The heat exchanger (lalK is equipped with a heater (29),
By controlling the current flowing through this heater η, the JT
The temperature at the outlet (b) of the high temperature flow path (a) of the heat exchanger αa is controlled by I, and when the heater (21) is not energized, the high temperature flow path (22) of the JT heat exchanger (181) is controlled. exit (b
The JT heat exchanger 0 mark is configured so that the temperature of ) is below the lambda point of helium. Further, the vacuum pump (23) is arranged to reduce the pressure at the outlet (d) of the low temperature flow path (24) of the JT heat exchanger Nishiki.

Next, the operation will be explained.

First, liquid helium of 4.2 is stored in the Hel tank αa through the Hel tank (13) and the connecting pipe (16) from the helium refrigerator housing 9, and after storing the liquid helium, the safety valve α is connected to the connecting pipe (
I6) and further store liquid helium in the Hel tank (13). In this state, He[tank I is Hel tank (13
) is pressurized at a pressure slightly higher than 1 atmosphere.

Next, the vacuum pump (22 is the low temperature flow path of the JT heat exchanger)
When the pressure is reduced to the pressure corresponding to the saturated vapor pressure of helium below the outlet of 241 (ψ is 1.8), 4.2 K is released from the HeI tank (13).

When liquid helium at a pressure of 1 atm flows into the inlet (a) of the high temperature flow path 0 of the JT heat exchanger o81 and reaches the JT valve (1, 9), it undergoes Joule-Thomson expansion to 4.2 and 1 atm. The molten helium cools to a temperature below 1.8 degrees, part of it vaporizes, and part of it becomes fluid superfluid helium and flows into the heat exchanger (201).This liquid superfluid helium is heated In the exchanger (201), the liquid helium is cooled and vaporized by heat exchange with the liquid helium in the He [tank (1 liter), and the low-temperature flow path (
24) into the inlet (C). This low temperature flow path (24
Since the helium gas flowing into the inlet (C) of ) is cooled to below 4.2 K, it is
The J
Outlet (d) of the low temperature flow path (24) of the T heat exchanger (18)
From there, it returns to the vacuum pump (22).

By repeating the above steps, the cooling of the liquid helium in the He1l tank 0 (a) is accelerated, and the high temperature flow path of the JT heat exchanger phase (
There are cases where the temperature at the outlet (b) of 22) becomes below the lambda point. The temperature at the outlet (b) of this high-temperature channel (22) is shown and measured by germanium temperature calculation.

The high temperature flow path (22) of the JT heat exchanger (18) is controlled by controlling the current of the heater (2υ) based on this measured temperature
The temperature of the liquid helium at the outlet (b) can be controlled so that it does not fall below the lambda point.

[Brief explanation of the drawing]

Figure 1 is a flowchart of a liquefier using a conventional heat exchanger, Figure 2
FIG. 3 is a schematic diagram of a heat exchanger according to the present invention, and FIG. 3 is a schematic diagram of a pressurized superfluid helium refrigerator using the heat exchanger according to the present invention. 5.24...Low temperature channel, 6.22...High temperature channel, 7.21...Heater. 305 Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A heat exchanger characterized in that a heater is provided near a flow path for heat exchange, and the temperature of heat exchange is controlled by changing the current flowing through the heater.