CN101592554A - A kind of liquid helium heat sink support structure that reduces experimentation cost - Google Patents

Abstract

The liquid helium heat sink support structure that is used for space environment simulation equipment, by liquid nitrogen heat sink and skeleton thereof, liquid helium is heat sink, the teflon pad is formed, liquid helium is heat sink to be directly installed on the liquid nitrogen heat sink by the teflon pad.This structure can make heat sink minimizing one cover skeleton, thereby has increased the efficiency test space of vacuum tank inside, has reduced the venting rate of vacuum tank internal material, has improved the static vacuum tightness of vacuum tank inside; Simultaneously, material requested reduces, and the liquid helium amount that the precooling liquid helium is heat sink to be needed to consume also reduces, thereby experimentation cost is reduced.

Description

A kind of liquid helium heat sink support structure that reduces experimentation cost

[technical field]

The present invention relates to a kind of liquid helium heat sink support structure that subtracts experimentation cost.The present invention is used in particular for a kind of liquid helium heat sink support structure that liquid helium consumes that reduces.

[background technology]

Heat sink is the important component part of space environment simulation equipment, and its effect is the cold darkness environment of virtual space on the ground.At present, hot vacuum environment simulated test facility both domestic and external mostly adopts the cold darkness environment of liquid nitrogen heat sink simulation space, but for the system that requires final relief amount, big pumping speed, the vacuum tightness that can simulate is not high, can only simulate the following environmental pressure of 100km.Along with the swift and violent development of China Aerospace, the needs of final relief loading gage people space flight, the demand of rocket engine plume test, adopt liquid nitrogen heat sink can't reach testing requirements, this just requires to adopt liquid helium heat sink, it can simulate the above environmental pressure of 100km, more approaches real vacuum cryogenic environment.

The engine plume testing generally adopts nitrogen to simulate real gas as actuating medium, at this moment, liquid nitrogen heat sink can not adsorb jet cutting car flow nitrogen, can't keep certain dynamic vacuum degree, jet flow nitrogen can only adopt that liquid helium is heat sink to be adsorbed, to keep sufficiently high dynamic vacuum degree.

The liquid helium that plume testing is used is heat sink to be protected by liquid nitrogen heat sink; to reduce vacuum tank to the heat sink thermal load of liquid helium; when being the engine plume testing; must adopt two-layer heat sink; inner heat sink is that liquid helium is heat sink; liquid helium is heat sink to be mainly used in gas absorption, and external heat sink is a liquid nitrogen heat sink, and liquid nitrogen heat sink is mainly used in to liquid helium heat sink cold screen protection and protects.

In order to guarantee heat sink operate as normal, it must have stable supporting construction, and traditional supporting construction comprises two aspects, the one, the support between heat sink and the skeleton, another be heat sink with the skeleton support of back in vacuum tank that fuse.The key of supporting construction is to allow heat sink can freely stretch under cold and hot temperature cycles, does not produce bigger temperature stress.On the strong point of heat sink skeleton and container, add mat insulation, can save liquid nitrogen consumption and avoid chamber wall frosting or dewfall.According to conventional design method, the two-layer heat sink skeleton that should adopt respectively that is used for plume testing supports, as shown in Figure 1, mainly by roller support (6), liquid helium is heat sink and skeleton (7), liquid nitrogen heat sink and skeleton (8) thereof, vacuum tank (9) are formed.For the big and cheap liquid nitrogen of the latent heat of vaporization, this supporting construction is owing to the liquid nitrogen consumption that heat conduction and radiation cause is few, and the additional testing cost of generation is not high.But the little and expensive liquid helium for the latent heat of vaporization, this supporting construction is owing to the liquid helium consumption that heat conduction and radiation cause sharply increases, and the additional testing cost sharply raises.

[summary of the invention]

The purpose of this invention is to provide a kind of simple, liquid helium heat sink support structure that can reduce experimentation cost, promptly cancel the heat sink skeleton of traditional liquid helium, heat sink and the liquid nitrogen heat sink of liquid helium is designed to one, and liquid helium is heat sink to be directly installed on the liquid nitrogen heat sink by the teflon pad.The liquid nitrogen heat sink equivalence is become the heat sink skeleton of liquid helium, thereby reduced the liquid measure that precooling liquid helium skeleton is consumed.

A kind of liquid helium heat sink support structure that reduces experimentation cost by teflon pad (1), roller support (2), liquid helium is heat sink (3), liquid nitrogen heat sink and skeleton (4) thereof, vacuum tank (5) are formed.

The advantage that the present invention has is: (a) liquid helium is heat sink is directly installed on above the liquid nitrogen heat sink by the teflon pad, has reduced the heat sink skeleton of a cover; (b) increased the efficiency test space of vacuum tank inside; (c) reduced the venting rate of vacuum tank internal material; (d) improved the static vacuum tightness of vacuum tank inside; (e) reduced the heat sink liquid helium amount that needs consumption of precooling liquid helium; (f) material reduces, and processing cost reduces; (g) consumption liquid is few, and experimentation cost reduces.

[description of drawings]

Fig. 1 is traditional heat sink skeleton form

Fig. 2 is equivalent heat sink skeleton form

[embodiment]

Further specify the present invention below in conjunction with accompanying drawing.

1, the heat sink precooling process analysis of liquid helium

In order to reduce liquid helium consumption, during precooling, in the liquid helium heat sink pipeline, charge into liquid nitrogen earlier, make the heat sink 100K that fully is pre-chilled to of liquid helium, it is heat sink to utilize liquid helium to continue the precooling liquid helium then, when the liquid helium heat sink temperature reaches the 10K left and right sides, begins to do experiment.

In the precooling process, total liquid helium consumption formula is as follows:

V _He＝V _He1+V _He2

$V_{\mathrm{<figure-callout\; id="1"\; label="He"\; filenames="A2009100881080007H1.png"\; state="\{\{state\}\}">He</figure-callout>}1}=\frac{Q}{(h_2-h_1){\mathrm{\&rho;}}_{\mathrm{He}}}$

In the formula:

V _He---total liquid helium consumption, m3;

V _He1---the liquid helium amount that the precooling liquid helium is heat sink self need to be consumed, m3 does not comprise skeleton;

V _He2---overcome the liquid helium amount that static load need consume, m3, static load comprises various heat radiations and heat conduction, mainly by liquid nitrogen heat sink, and skeleton produce;

Q---the precooling liquid helium is heat sink institute's chilling requirement, kJ;

h ₁---the enthalpy of porch liquid helium correspondence that liquid helium is heat sink, kJ/kg;

h ₂---the enthalpy of exit gas helium correspondence that liquid helium is heat sink, kJ/kg;

ρ _He---liquid helium density.

2, during precooling, the liquid helium consumption comparative analysis of heat sink skeleton of traditional liquid helium and the heat sink skeleton of equivalent liquid helium

By total liquid helium consumption formula as can be seen, no matter adopt which kind of skeleton form, the liquid helium amount V that the heat sink sole mass of precooling liquid helium need consume _He1Constant, overcome the liquid helium amount V that static load need consume as long as analyze _He2Get final product.Static load comprise liquid nitrogen heat sink to the heat sink radiation of liquid helium, skeleton by teflon to the heat sink heat conduction of liquid helium, skeleton to the heat sink radiation of liquid helium.Wherein, no matter adopt which kind of skeleton form, liquid nitrogen heat sink is constant to the heat sink radiation of liquid helium, and the last analysis skeleton that only needs gets final product the heat sink radiation size of liquid helium liquid helium heat sink heat conduction and skeleton by teflon.

Plume testing vacuum tank with size Ф 5.2m * 12.6m is an example, its liquid helium is heat sink size Ф 4.0m * 9.9m, and liquid nitrogen heat sink size Ф 4.6m * 9.9m, test gas is a nitrogen, and flow is 2g/s, and static vacuum tightness is 10 ^-6Pa, dynamic vacuum degree are 10 ^-3Pa.

Liquid helium is heat sink and the skeleton quality is as shown in the table, and as can be seen from the table, the skeleton quality is suitable with heat sink quality, and as skeleton not being done special processing, only the liquid helium amount that consumed of this part quality of precooling is just considerable.

Stainless-steel tube quality (Kg)	Copper fin quality (Kg)	Stainless steel insert quality (Kg)
			1458	2913	4847

(1) skeleton is as follows to the heat sink radiation computing formula of liquid helium:

${\mathrm{<figure-callout\; id="1"\; label="Q"\; filenames="A2009100881080007H1.png"\; state="\{\{state\}\}">Q</figure-callout>}}_1=\frac{\mathrm{\&sigma;}{A}_1({\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A2009100881080007H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_2^4-{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="A2009100881080007H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_1^4)}{\frac{1}{{\mathrm{\&epsiv;}}_1}+\frac{A_1}{A_2}(\frac{1}{{\mathrm{\&epsiv;}}_2}-1)}$

In the formula:

Q ₁---radiant heat transfer speed, W;

A ₁---the heat sink external surface area of liquid helium, m ²

A ₂---the skeleton internal surface area.Get m ²

σ---this base of a fruit fence-Boltzmann constant;

T ₁---the liquid helium heat sink temperature;

T ₂---the skeleton temperature;

ε ₁---liquid helium is heat sink outside surface absorption coefficient;

ε ₂---liquid nitrogen heat sink inside surface absorption coefficient.

Obtain skeleton at last to the heat sink thermal load Q of liquid helium ₁=123W takes away this portion of hot load and needs to consume the liquid helium amount $V_{\mathrm{He}}=\frac{Q\&times;3600}{{\mathrm{\&rho;}}_{4.2K}({\mathrm{\&gamma;}}_{4.2K}+{\mathrm{\&Delta;H}}_{20K-4.2K})}=\frac{123\&times;3600}{124.9(20.9+87.8)}=33L/h,$ Precooling process was calculated by 5 hours, then consumed the 165L liquid helium altogether.

The heat sink skeleton of equivalence liquid helium is support with the liquid nitrogen heat sink, so there is not this consumption.

(2) cross teflon to the heat sink heat conduction of liquid helium:

The heat conduction computing formula is as follows:

${\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="A2009100881080007H1.png"\; state="\{\{state\}\}">Q</figure-callout>}}_2=A_m\mathrm{\&lambda;}(T_g-T_d)\frac{1}{L}$

In the formula:

Q ₂---heat conduction amount, W;

A _m---heat conduction contact area, m ², 0.01;

λ---material thermal conductivity, W/ (mk), teflon gets 0.29;

T _g---material at high temperature end temperature (skeleton temperature), K;

T _d---low-temperature end temperature (helium plate temperature), K;

For the heat sink skeleton of traditional liquid helium, when liquid helium begins precooling, the skeleton temperature T _gBe higher than 100K, according to the use experience of KM series vacuum tank, T _g(mainly be because the skeleton quality is too heavy, cause thermal capacitance big, rate of temperature fall is slow, and heat sink when reaching 100K, skeleton does not also cool down for ≈ 150K.), calculate Q ₂=696W, the liquid helium amount that needs to consume is 184L/h, precooling process was calculated by 5 hours, then consumed the 920L liquid helium altogether.

For the heat sink skeleton of equivalent liquid helium, when liquid helium began precooling, equivalent skeleton (liquid nitrogen heat sink) temperature was 100K, T _g=100K obtains Q ₂=522W, the liquid helium amount that needs to consume is 138L/h, precooling process was calculated by 5 hours, then consumed the 690L liquid helium altogether.

	Radiation consumption liquid/L	Heat conduction consumption liquid/L	Total consumption liquid	Consumption liquid total price/ten thousand
					The heat sink skeleton of tradition	165	920	1085	21.7
The heat sink skeleton of equivalence	0	690	690	13.8

As can be seen from the above table, adopt equivalent heat sink skeleton form, can save experimentation cost, save 7.9 ten thousand yuan at every turn approximately, economic worth is very considerable.

Claims (1)

1, liquid helium heat sink support structure, mainly by liquid nitrogen heat sink and skeleton thereof, liquid helium is heat sink, the teflon pad is formed, it is characterized in that: liquid helium is heat sink to be directly installed on the liquid nitrogen heat sink by the teflon pad.

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