CN1514232A - Method and device for determining latent heat in freezing or melting process of biological sample - Google Patents

Abstract

The method for determining the phase change latent heat in the freezing or melting process of the biological sample comprises the following steps: freezing or melting a biological sample to be tested to generate a changing temperature field inside the sample; acquiring transient temperature information of each space in the freezing or melting direction in a biological sample temperature field, inputting the transient temperature information into a computer for finite difference data processing to obtain the temperature gradient, the thermal conductivity and the moving speed of the two sides of a solid-liquid interface of the biological sample to be detected in the freezing or melting direction, and obtaining the latent heat of the biological sample to be detected by using an energy continuous equation at the solid-liquid interface of the biological sample to be detected; the device comprises: the refrigerator, the sample chamber, the temperature sensor, the auxiliary flat sheet, the data acquisition instrument, the computer and the like; the thermocouple lead is connected to a data acquisition instrument communicated with a computer; the device has the advantages of high test precision, high response speed, simple structure, low cost, simple and convenient operation and wide application range.

Description

Measure that biological sample freezes or melting process in the method and the device of latent heat

Technical field

The present invention relates to a kind of based on biological sample freeze or melting process in temperature information measure the measuring method and the device of biological sample latent heat to be measured.

Background technology

Cryobiology is emerging in recent years and obtains the cross discipline of fast development that along with going deep into of research, its application in all trades and professions is noticeable.The medical science aspect, freezing preservation biomaterial for medical purpose and to transplant be one of most active fields in the current cryogenic medicine.The freezing preservation of biomaterial for medical purpose comprises: the freezing preservation of blood cell, hematopoietic cell, reproduction cell; The cryopreservation of skin, cornea, bone and cartilage, cardiac valves and trunk, incretory and organ etc.Except that freezing preservation, cryosurgery is cryobiology another crucial application aspect medical science.Cryosurgery is to utilize the cryogenic freezing method to destroy pathology, reaches the purpose of removing focus at last, so be called cryosurgery again.At present, cryosurgery has all obtained application in many clinical subjects, as the department of stomatology, dept. of dermatology, ear-nose-throat department, ophthalmology, surgery, gynaecology etc.Wherein, the various oncotherapies of surgical field are of greatest concern.On the other hand, in industries such as farming, woods, medicine, food, cryobiology has also been brought huge benefit, such as also having produced far-reaching influence at aspects such as saving rare plant in imminent danger, protection biology.

The application of above cryobiology generally speaking, can be divided into cryopreservation and cryosurgery.In this two class was used, low temperature has reached preserved or destroys cell tissue function and these two kinds of distinct purposes of structure.Studies show that the heating rate of the rate of temperature fall of the damage of cell and tissue and refrigerating process and rewarming process has substantial connection (Liu Jingang, Liu Zuobin chief editor, cryogenic medicine, Beijing: People's Health Publisher, 1993) in cryopreservation and the cryosurgery.Therefore, in freezing and the rewarming process, setting up suitable cooling heating schedule is successful key factor.And, inevitably can run into the phase transformation problem here.And to the research of phase transformation problem, latent heat parameter definite essential.In a word, for above-mentioned reasons, be the target that people competitively explore with regard to the latent heat of phase change measuring method of biomaterial and the research of instrument always.

The latent heat of phase change of measuring biomaterial generally all adopts DSC (Differential Scanning Calorimetry) method.On the one hand the used instrument of this method is very expensive, and it is very loaded down with trivial details to operate.Most importantly, be subjected to the restriction of its principle, this method is essential to adopt enough little cooling and heating rate, thereby can't record the latent heat of phase change under different coolings and the heating rate.In addition, the latent heat that the DSC method records is actual to be latent heat and sensible heat sum, and only sensible heat wants specific latent heat little a lot of comparatively speaking, and this can introduce new measuring error inevitably.At present, also there is not a kind of method can record latent heat of phase change under different coolings and the heating rate.For this reason, the invention provides a kind of new assay method that the broad applicability is arranged, not only very important to the research in low-temperature biological field, and to other research that relates to the field of phase transformation (solidify or melt or melt) such as alloy material etc. also highly significant.

Summary of the invention

The object of the present invention is to provide a kind of measure that biological sample freezes or melting process in the method for latent heat;

Another object of the present invention is to provide a kind of measure that biological sample freezes or melting process in the device of latent heat;

Technical scheme of the present invention is as follows:

Mensuration biological sample provided by the invention freeze or melting process in the method for latent heat, its step is as follows:

(1) sample is implemented to freeze or melt, to cause the temperature field of variation in sample interior;

(2) gather in the biological sample temperature field along freezing or melt the transient state solid-state temperature T at director space each point x place _sAnd liquidus temperature T _lInformation;

(3) the transient temperature information that obtains is inputed to carry out the finite difference data processing in the computing machine, obtain biological sample to be measured along freezing or melt the thermograde T of solid, liquid intersection interface s both sides on the direction _s/ x, T _l/ x, wherein T _s/ x is the thermograde of solid phase one side at the interface, obtains T by the space each point finite difference of solid phase one side temperature _l/ x is the thermograde of liquid phase one side at the interface, is obtained by the space each point finite difference of liquid phase one side temperature; The solid phase temperature conductivity k of testing sample _sAnd liquid phase temperature conductivity k _l, be known as k by introducing a thermal conductivity _aAuxiliary heat conduction plain film, in obtaining upper and lower surface of this plain film and plain film one side sample, a bit behind temperature information at place, obtain by the reference method; The rate travel ds/dt at phase transformation interface obtains by the time difference of the interface location s of difference moment t; Utilize the energy continuity equation at tested biological sample solid, liquid intersection interface s place $L={\frac{(k_s{\·\∂T}_s/\∂x-k_l{\·\∂T}_l/\∂x)}{\mathrm{ds}/\mathrm{dt}}|}_s$ Draw the latent heat L of biological sample to be measured; Described biological sample to be measured is solid-state biological sample or series of liquid biological samples.

Mensuration biological sample provided by the invention freeze or melting process in the measurement mechanism of latent heat of phase change, comprise: refrigerator c, sample chamber f, temperature sensor, data collecting instrument and computing machine, the plane refrigerator of described refrigerator c for constituting by multistage Peltier semiconductor refrigerating element, place sample chamber f on its refrigerator c upper surface, the place, lower surface is provided with the heating radiator b of band radiated rib, is provided with heat conduction copper sheet d between refrigerator c and the sample chamber f; Scribble conduction estersil between heat conduction copper sheet d and refrigerator c and the sample chamber f; F bottom in sample chamber is provided with the known auxiliary plain film j1 of a thermal conductivity, and the lower surface center position of auxiliary flat j1 is embedded with temperature sensor 1; F top, sample chamber is provided with the known auxiliary flat j2 of a thermal conductivity, inlays temperature sensor 8 and 9 on its upper and lower surface respectively; Auxiliary plain film j2 is fixedly connected with the piston k that can slide in the vertical through hole of sample chamber upper cover plate; Vertical among the f of sample chamber 2-7 temperature sensor be set; The lead-in wire of temperature sensor is drawn by the center pit of piston k, and is connected the input end of data collecting instrument; The input end of data collecting instrument drawn and is connected by temperature sensor 1,8 and 9 lead-in wire by sample chamber f, the output port of data collecting instrument carries out the finite difference data processing with the transient temperature data that are used for the thermopair input, and the computing machine input port that draws the sample latent heat of phase change links to each other;

Described sample chamber f is made by glass or organic glass, and its inner space is that 10mm * 10mm * 10mm is between 100mm * 100mm * 100mm; Described sample chamber f outer wall is carved with scale; Sample chamber f arranged outside plexiglass tent; The upper surface area of described refrigerator c is that 10mm * 10mm is to 100mm * 100mm scope; The radiated rib of described heating radiator b is made by aluminium or copper; The power supply of described refrigerator c is the adjusting power supply of adjustable voltage size; The high heat-conducting copper sheet thickness that described refrigerator c upper surface covers is 0.1 to 2mm; Auxiliary plain film j1, j2 are the auxiliary plain film that glass or plastics are manufactured.

Below test philosophy provided by the invention is illustrated:

In the measurement approach of the various thermal parameters of biomaterial, by the use of thermal means is because of its simple and direct property and cheaply come on the scene gradually.From the calorifics angle, the present invention provides a kind of method and apparatus of novel mensuration biological sample latent heat.

Sample has general applicability in thermal process heat balance relational expression is,

$\mathrm{\ρc}=\frac{\∂T}{\∂t}=\▿\·(k\▿T)---\left(1\right)$

ρ wherein, c is respectively density, the specific heat of sample; K is the thermal conductivity of sample.

Following formula can further be expressed as:

$\mathrm{\ρc}\frac{\∂T}{\∂t}=\frac{\∂}{\∂x}\left(k\frac{\∂T}{\∂x}\right)+\frac{\∂}{\∂y}\left(k\frac{\∂T}{\∂y}\right)+\frac{\∂}{\∂z}\left(k\frac{\∂T}{\∂z}\right)----\left(2\right)$

For for simplicity, we only consider the one dimension situation, and the biomaterial thermal conductivity is generally got constant, so (2) formula abbreviation is

$\mathrm{\ρc}\frac{{\∂T}_s}{\∂t}=k\frac{{\∂}^2{T}_s}{{\∂x}^2}----\left(3\right)$

After biomaterial underwent phase transition, the thermal conductivity of freezing phase changed, and the thermal conductivity of not freezing phase is constant.Freeze like this to be respectively with the heat balance relational expression of not freezing mutually

$\mathrm{\ρc}\frac{{\∂T}_s}{\∂t}=k_s\frac{{\∂}^2{T}_s}{{\∂x}^2}-----\left(4\right)$

$\mathrm{\ρc}=\frac{{\∂T}_l}{\∂t}=k_l\frac{{\∂}^2{T}_l}{{\∂x}^2}----\left(5\right)$

K wherein _s, k _lBe respectively and freeze and the thermal conductivity of not freezing mutually, subscript s, l represent solid phase and liquid phase respectively.

Freezing and the interface place that does not freeze mutually, can get by energy conservation relation

$k_s\frac{{\∂T}_s}{\∂x}-k_l\frac{{\∂T}_l}{\∂x}=L\frac{\mathrm{ds}}{\mathrm{dt}},x=s-----\left(6\right)$

Wherein, L is a latent heat of phase change to be measured, and s is the position at phase transformation interface.

Can set up practical latent heat of phase change measuring method in view of the above, its basic thought is: the multi-point temp probe that will comprise spatial information inserts in the testing sample, and collects the temperature data of each measuring point, then can obtain latent heat of phase change by formula (6) to be

$L=\frac{(k_s\·\∂T_s/\∂x-k_l\·\∂T_l/\∂x)}{\mathrm{ds}/\mathrm{dt}}{|}_{x=s}------\left(7\right)$

Like this, the measurement of latent heat of phase change is just summed up in the point that and is realized k _s, k _l, ${\frac{{\∂T}_s}{\∂x}|}_{x=s},{\frac{{\∂T}_l}{\∂x}|}_{x=s}$ And Mensuration come up.Key of the present invention is to design corresponding temperature measuring equipment and determines above each parameter (k by temperature survey _s, k _l, ${\frac{{\∂T}_s}{\∂x}|}_{x=s},{\frac{{\∂T}_l}{\∂x}|}_{x=s}$ And

), thereby draw latent heat of phase change.Fig. 1 has provided the structure diagram of entire measuring device, and the solid stain in the middle of the sample stage is the signal of 9 pieces of temperature sensors (as thermopair), the stationkeeping of temperature sensor point for measuring temperature, and vertical range each other pre-determines, and numbering from top to bottom is followed successively by 1,2,3 ..., 9.The thermal conductivity of two auxiliary plain film j is known up and down, is k _aTemperature sensor 1,2 and 8,9 is separately fixed at the upper and lower surface of downside and upside plain film j, to measure the temperature at position, place separately.Freezing process with biological sample is example (measurement of melting process similarly) below, provides k _s, k _l, ${\frac{{\∂T}_s}{\∂x}|}_{x=s},{\frac{{\∂T}_l}{\∂x}|}_{x=s}$ And Based on thermometric computing method.Be located under the effect of freezing device c, the freezing process in the sample develops from bottom to top.So, can at first determine the thermal conductivity k that freezes phase _s, the sample of temperature sensor 3 positions freezes the back, and (whether the sample of a certain position freezes and can be judged by the temperature of this position: if T＞T _m, then do not freeze; If T＜T _m, then frozen; If T=T _m, then the phase transformation interface is in this position.Here T _mSolidifying point for sample), the energy conservation relation of temperature sensor 2 positions can be by following differential type approximate representation

$k_a\frac{T_2-T_1}{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">d</figure-callout>}}_{\mathrm{1,2}}}=k_s\frac{T_3-T_2}{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">d</figure-callout>}}_{\mathrm{2,3}}}----\left(8\right)$

D wherein _1,2, d _2,3Be respectively the vertical range between the temperature sensor 1 and 2,2 and 3.Like this, the thermal conductivity of freezing phase can be determined by following formula

$k_s=\frac{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">\; <figure-callout\; id="3"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">d</figure-callout>\; </figure-callout>}}_{\mathrm{2,3}}\&CenterDot;(T_2-T_1)}{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">d</figure-callout>}}_{\mathrm{1,2}}\&CenterDot;(T_3-T_2)}{k}_a----\left(9\right)$

Do not freeze the thermal conductivity k of phase _lDefinite method similar with the thermal conductivity of freezing mutually.Before the sample of temperature sensor 7 positions freezed, the differential type form of the energy conservation relation of temperature sensor 8 positions was

$k_a\frac{T_9-T_8}{d_{\mathrm{8,9}}}=k_l\frac{T_8-T_7}{{\mathrm{<figure-callout\; id="7"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">d</figure-callout>}}_{\mathrm{7,8}}}----\left(10\right)$

D wherein _7,8, d _8,9Be respectively the vertical range between the temperature sensor 7 and 8,8 and 9.Like this, the thermal conductivity of not freezing phase can be determined by following formula

$k_l=\frac{{\mathrm{<figure-callout\; id="7"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">d</figure-callout>}}_{\mathrm{7,8}}\&CenterDot;(T_9-T_8)}{d_{\mathrm{8,9}}\&CenterDot;(T_8-T_7)}{k}_a------\left(11\right)$

Above plain film method calorimetric conductance generally needs enough big thermograde.For reducing the measuring error of above-mentioned thermal conductivity, require the phase transformation interface can not be too far away from temperature sensor 3 positions when the thermal conductivity of phase is freezed in calculating, same calculating requires the phase transformation interface can not be too far away from temperature sensor 7 positions when not freezing the thermal conductivity of phase.

Provided k above _sAnd k _lComputing method, what then provide is ${\frac{{\&PartialD;T}_s}{\&PartialD;x}|}_{x=s},{\frac{{\&PartialD;T}_l}{\&PartialD;x}|}_{x=s}$ And Computing method.By temperature sensor 2,3,4 ..., 8 time dependent temperature curves, we can know temperature sensor 2,3,4 ..., the concrete time t that undergoes phase transition of the sample of 8 positions ₂, t ₃, t ₄..., t ₈Below we are the example explanation with node 3 ${\frac{{\&PartialD;T}_s}{\&PartialD;x}|}_{x=s},{\frac{{\&PartialD;T}_l}{\&PartialD;x}|}_{x=s}$ And

Computing method.When the phase transformation interface moves to node 3

${\frac{{\&PartialD;T}_s}{\&PartialD;x}|}_{x=s}=\frac{T_3-T_2}{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">\; <figure-callout\; id="3"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">d</figure-callout>\; </figure-callout>}}_{\mathrm{2,3}}},t=t_3----\left(12\right)$

${\frac{{\&PartialD;T}_l}{\&PartialD;x}|}_{x=s}=\frac{T_4-T_3}{{\mathrm{<figure-callout\; id="3"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">\; <figure-callout\; id="4"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">d</figure-callout>\; </figure-callout>}}_{\mathrm{3,4}}},t=t_3---\left(13\right)$

$\frac{\mathrm{ds}}{\mathrm{dt}}=\frac{d_{23}}{t_3-t_2}-----\left(14a\right)$

Or

$\frac{\mathrm{ds}}{\mathrm{dt}}=\frac{{\mathrm{<figure-callout\; id="3"\; label="d"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">d</figure-callout>}}_{\mathrm{3,4}}}{t_4-t_3}----\left(14b\right)$

Wherein, d _3,4Be the vertical range between temperature sensor 3 and 4, ds/dt can be determined by any same form in formula (14a) or the formula (14b).For node 4,5,6 and 7, also can calculate accordingly by formula (12)-Shi (14) ${\frac{{\&PartialD;T}_s}{\&PartialD;x}|}_{x=s},{\frac{{\&PartialD;T}_l}{\&PartialD;x}|}_{x=s}$ And

With the above k that calculates _s, k _l, ${\frac{{\&PartialD;T}_s}{\&PartialD;x}|}_{x=s},{\frac{{\&PartialD;T}_l}{\&PartialD;x}|}_{x=s}$ And Substitution formula (7), the latent heat of phase change of detected materials can be measured.

In this latent heat measurement mechanism, temperature sensor 9 also can.Each parameter k of front _s, k _l, ${\frac{{\&PartialD;T}_s}{\&PartialD;x}|}_{x=s},$ ${\frac{{\&PartialD;T}_l}{\&PartialD;x}|}_{x=s}$ And Calculating in, have only k _lNeed use the temperature at node 9 places.Below provide temperature, do not freeze phase thermal conductivity k without node 9 _lComputing formula.(the t=t when sample of temperature sensor 5 positions freezes ₅The time), the difference form of formula (4) and formula (5) is respectively

$\mathrm{\&rho;c}=\frac{{{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_3|}_{t=t_5}-{{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_3|}_{t=t_4}}{t_5-{\mathrm{<figure-callout\; id="4"\; label="t"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">t</figure-callout>}}_4}=k_{\mathrm{<figure-callout\; id="4"\; label="s\; T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">s</figure-callout>}}\frac{{T_{}}_{}}{}\frac{{{}_4|}_{t=t_5}-{{2\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_3|}_{t={\mathrm{<figure-callout\; id="5"\; label="t"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">t</figure-callout>}}_5}+{{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_2|}_{t=t_5}}{d^2}----\left(15\right)$

$\mathrm{\&rho;c}=\frac{{{\mathrm{<figure-callout\; id="7"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_7|}_{t=t_5}-{{\mathrm{<figure-callout\; id="7"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_7|}_{t=t_4}}{t_5-{\mathrm{<figure-callout\; id="4"\; label="t"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">t</figure-callout>}}_4}=k_l\frac{{T_8|}_{t=t_5}-{{2\mathrm{<figure-callout\; id="7"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_7|}_{t={\mathrm{<figure-callout\; id="5"\; label="t"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">t</figure-callout>}}_5}+{{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_6|}_{t=t_5}}{d^2}----\left(16\right)$

Here convenient for statement, make d _2,3=d _3,4=d, d _6,7=d _7,8=d.Two formulas can get above the simultaneous

$\frac{k_l}{k_s}=\frac{{{\mathrm{<figure-callout\; id="4"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_4|}_{{t=t}_5}-{{2\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_3|}_{{t=\mathrm{<figure-callout\; id="5"\; label="t"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">t</figure-callout>}}_5}+{{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_2|}_{{t=t}_5}}{{T_8|}_{{t=t}_5}-{2{\mathrm{<figure-callout\; id="7"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_7|}_{{t=\mathrm{<figure-callout\; id="5"\; label="t"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">t</figure-callout>}}_5}+{{\mathrm{<figure-callout\; id="6"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_6|}_{{t=\mathrm{<figure-callout\; id="5"\; label="t"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">t</figure-callout>}}_5}}\&CenterDot;\frac{{{\mathrm{<figure-callout\; id="7"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_7|}_{{t=t}_5}-{{\mathrm{<figure-callout\; id="7"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_7|}_{{t=t}_4}}{{{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_3|}_{{t=t}_5}-{{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="A0216020100152.png"\; state="\{\{state\}\}">T</figure-callout>}}_3|}_{{t=t}_4}}-----\left(17\right)$

Provided in the formula (9) and freezed phase thermal conductivity k _sExpression formula, with its substitution following formula, do not freeze phase thermal conductivity k _lCan determine.

Thus, according to the transient temperature that each point collects, just can obtain the latent heat of phase change of testing sample.Whole process is write down automatically and calculates automatically in conjunction with computing machine by data collecting instrument.The user can read measured latent heat of phase change by display screen.

Task of the present invention is to be to provide a kind of novel method and device of measuring the latent heat of phase change of biomaterial under difference cooling or heating rate according to above-mentioned principle, and its embodiment is as follows:

Measurement biological sample provided by the invention freezes or melts the method for latent heat, it is characterized in that:

1. sample latent heat obtains by measuring the sample temperature that reaches spatial variations in time;

2. this method also can be measured the thermal conductivity of freezing sample and not freezing sample simultaneously.

The measurement mechanism of biological sample latent heat of phase change to be measured provided by the invention, comprise: refrigerator c, sample chamber f, temperature sensor, data collecting instrument and computing machine, the plane refrigerator of described refrigerator c for constituting by multistage Peltier semiconductor refrigerating element, place sample chamber f on its refrigerator c upper surface, the place, lower surface is provided with the heating radiator b of band radiated rib, is provided with heat conduction copper sheet d between refrigerator c and the sample chamber f; Scribble conduction estersil between heat conduction copper sheet d and refrigerator c and the sample chamber f; F bottom in sample chamber is provided with the known auxiliary flat j1 of a thermal conductivity, and the lower surface center position of auxiliary flat j1 is embedded with temperature sensor 1; F top, sample chamber is provided with the known auxiliary flat j2 of a thermal conductivity, inlays temperature sensor 8 and 9 on its upper and lower surface respectively; Auxiliary flat j2 goes up and connects the piston k that can slide up and down; Vertical setting is provided with 2-7 temperature sensor from the bottom to top successively in the sample among the f of sample chamber; The lead-in wire of this 2-7 temperature sensor is drawn by the center pit of piston k, and is connected the input end of data collecting instrument; The input end of data collecting instrument is drawn and be connected to temperature sensor 1,8 and 9 lead-in wire by sample chamber f, and the output port of data collecting instrument links to each other with the computing machine input port that is used for the transient temperature data of thermopair input are handled and calculated the sample latent heat of phase change; Described sample chamber is made by glass or organic glass, and its inner space is that 10mm * 10mm * 10mm is between 100mm * 100mm * 100mm; Described sample chamber outer wall is carved with scale, and the sample chamber has cover plate; Sample chamber arranged outside plexiglass tent; Radiated rib is made by aluminium or copper; The power supply of described refrigerator is the adjusting power supply of adjustable voltage size; The high heat-conducting copper sheet thickness that described refrigerator upper surface covers is 0.1 to 2mm; Auxiliary plain film is the auxiliary plain film that glass is manufactured.

Mensuration biological sample provided by the invention freeze or melting process in the measurement mechanism of latent heat of phase change, compact conformation, response speed is fast, cost is low, and operate very easy, can implement different cooling or heating rate by changing the refrigerator input voltage to biological sample easily, by the latent heat of phase change that the accurately fixing temperature sensor of a plurality of relative positions (as thermopair etc.) draws the space of measured material temperature in phase transition process and time information quickly and easily and then obtains sample is set, and institute's tested object can be solid or liquid.Because the temperature sensor precision height that is adopted, response speed is fast, and temperature-measuring range is wide, thereby can satisfy the application of relative broad range.The most significant characteristics of native system are energy measurement biomaterial latent heats of phase change under difference cooling or heating rate.The latent heat of phase change measurement of biomaterial is that biomedical engineering circle is being attempted the target explored, and native system and the method that is adopted thereof have not yet to see report.

Description of drawings

Shown in Figure 1 is that structure of the present invention and temperature sensor are arranged synoptic diagram;

Fig. 2 is the position signal of layouting of the probe profile of fixed temperature sensor and thermopair;

Fig. 3 is probe interior structure and thermopair assembling signal;

Wherein: a-tank b-gilled radiator c-semiconductor cooler

D-heat conduction copper sheet e-plexiglass tent f-sample chamber

G-sample h-thermopair node i-thermocouple lead

J1, j2-assist plain film k-piston l-cover plate

Thermopair 1,2,3,4,5,6,7,8,9 piston k

Thin walled tube 31

Embodiment

The present invention is described in further detail below in conjunction with the drawings and specific embodiments.

As shown in Figure 1, the measurement mechanism of biological sample latent heat of phase change to be measured provided by the invention comprises refrigerator, is positioned at the sample chamber of refrigerator upper end; Be positioned at the radiated rib of refrigerator lower end; Be provided with the heat conduction copper sheet between refrigerator and the sample chamber; Scribble conduction estersil between heat conduction copper sheet and refrigerator and the sample chamber; The bottom of sample chamber is the known auxiliary plain film of a thermal conductivity; Should assist the center position of plain film lower surface to be embedded with temperature sensor 1; The sample upper surface covers the known auxiliary plain film of a thermal conductivity, and this plain film contacts fine with sample, and temperature sensor 8 and 9 is embedded in the upper and lower surface of this plain film respectively, and the plain film upper end is connected (when sample expansion or contraction, plain film can be free movable) with a piston; Temperature sensor 2-7 is arranged in the testing sample; If sample is a soft-tissue material, temperature sensor 2-7 thrusts (probe structure and temperature sensor are arranged and be shown among Fig. 2 and Fig. 3) in the testing sample by probe; If sample is a liquid, temperature sensor 2-7 can be arranged in the sample by probe, also can arrange by the fine rule that is fixed in advance on the auxiliary plain film in bottom, sample chamber; The cover plate that covers on the plexiglass tent outside the sample chamber and cover on the sample chamber is used for reducing the peripherad heat radiation in sample chamber.Its measuring accuracy height, response speed is fast, simple in structure, cost is low and the operation very easy, applied widely.

The plane refrigerator of described refrigerator for being made of multistage Peltier semiconductor refrigerating element, by the transposing positive and negative electrode, it both can be used to cool off sample freezes it, also can be used to heated sample and makes its thawing.In the use, can establish small-sized fans on the radiated rib or directly immerse in the tank so that in time the heat or the cold on fin surface are removed; The power supply of described refrigerator is the adjusting power supply of adjustable voltage size; The lead-in wire of described temperature sensor 2-7 is drawn by the passage of piston hollow, and the lead-out mode of temperature sensor 1,8,9 as shown in Figure 1.

Provided by the inventionly be used to measure that biological sample freezes or the device of latent heat of phase change when melting, comprise: tank a; Gilled radiator b; Multistage Peltier semiconductor cooler c; Heat conduction copper sheet d; Plexiglass tent e; Sample chamber f; Temperature sensor; Auxiliary plain film j; Piston k; Cover plate l; Data collecting instrument and computing machine (not shown, brief description is as follows: thermocouple lead links to each other with data collecting instrument, and data collecting instrument is input to computing machine with the data-signal that collects by data line again).Sample chamber f outer wall is carved with scale, for determining thermopair 1,2 ... relative position use.

Refrigerator c of the present invention adopts and is made of Peltier semiconductor refrigerating element, be easy on the market buy, with the integrated encapsulation of a series of such elements, then can form the plane refrigerator with a hot face and a chill surface, Peltier semiconductor refrigerating element can freeze or heating power to increase by plural serial stage.In case this integrated refrigerator energized (is connected with transformer, to obtain safe voltage and electric current), then side plane heating, the opposite side cooling, the person promptly plays refrigeration to connect the cold junction, be used for biological sample lowered the temperature and freeze, the sending and receiving hot junction then is a heat effect, can adjust the relative position of heating or chill surface by changing direction of current.Be to improve heating or refrigerating efficiency, can with radiated rib that refrigerator is connected on be furnished with a small fan and carry out air blast, by forcing the convection current of fin surrounding air heat or cold on the rib surface are removed rapidly; Also can directly radiated rib be immersed in the tank.Used radiated rib complete class is same as the finned radiator of buying easily on the market that is used for the cooling computer chip, thereby only need buy use and get final product.

The bottom of sample chamber is an auxiliary plain film j, and this auxiliary plain film is used for determining the thermal conductivity of sample, and for reducing measuring error, the thermal conductivity of itself can not too greatly also can not be too little, generally adopts materials such as organic glass or fiberglass.Based on this, the sample chamber is bonded with organic glass or fiberglass.The auxiliary plain film material therefor of sample formula upper end is identical with the sample chamber.The sectional dimension of sample chamber is controlled at 10mm * 10mm between 100mm * 100mm, highly is controlled at 10mm between the 100mm.Can be equipped with the sample chamber of different sizes, supply the measurement of the biological sample of different amounts or different size to select for use.Scribble conduction estersil between heat conduction copper sheet and refrigerator and the sample chamber.

The layout of multi-point temp measuring point as shown in Figure 1.Temperature sensor 1 is embedded in the center position of the auxiliary plain film lower surface of bottom, sample chamber; Temperature sensor 8 and 9 is embedded in the upper and lower surface of the auxiliary plain film above the sample respectively; Temperature sensor 2-7 is arranged in the testing sample; If sample is a soft-tissue material, temperature sensor 2-7 thrusts (probe structure and temperature sensor are arranged and be shown among Fig. 2 and Fig. 3) in the testing sample by probe; If sample is a liquid, temperature sensor 2-7 can be arranged in the sample by probe, also can arrange by the fine rule that is fixed in advance on the auxiliary plain film in bottom, sample chamber.Vertical range between the temperature sensor should be demarcated and be transported on the interior process software of computing machine.Temperature sensor can be selected thermopair for use, its temperature measuring head size should be advisable with minimum dimension under the prerequisite that can guarantee processing, the current commercial less thermocouple wire diameter that buys is 20 μ m, 80 μ m equidimensions, can directly use, or select the thermopair of special processing as required for use.

If temperature sensor 2-7 passes through probe stationary, the number of assembling steps of probe following (Fig. 3) then: on thin-walled 31 tube walls, leave micropore earlier by calibration position, form evenly distributed serial aperture, its diameter is about about 80-100 μ m, at these micropore places the node of thermopair 2-7 is welded on the wall, and exposes, so that contact with sample and measure this position temperature, the wire harness of thermopair is then drawn in the pipe of hollow, and wherein each piece thermocouple will be marked.For avoiding the heat conduction in the thin walled tube to cause bigger thermometric error, the coefficient of heat conductivity of pipe wall material should be as far as possible little, and as can adopting fiberglass or plastics etc., otherwise thermopair records will be pipe surface temperature but not the temperature of the position sample that touches.And the relative position between each thermopair is accurately fixing, and its coordinate information is stored in the data acquisition software.

The signal of temperature sensor is input to data collecting instrument, specifically can select the ratio of performance to price Agilent34970A type signals collecting and processor preferably for use.The used computing machine of native system adopts plain edition to get final product, and price is very cheap, and performance meets the demands fully.

From the above mentioned, the temperature sensor of the present invention's employing derives from thermopair (1,2, ..., 9), its response speed is very fast, and the precision height, it is cheap that price then is tending towards, the making of whole device and assembling are relatively easy, data acquisition and handle very convenient, no complicated circuit, simple in structure, test specification wide (can accurately demarcate in the different temperatures scope thermopair and realize).In case record thermopair 1,2 in the freezing process ... the temperature information of locating, then can determine the latent heat of phase change of institute's test sample product based on aforementioned principles.Native system is suitable for the measurement of biological sample latent heat of phase change under different coolings or the heating rate.

Embodiment: utilize the latent heat of phase change of this measurement device biological sample, can divide and freeze and the two class situations of melting are carried out.Here introduce the measuring process that freezes under the situation earlier: at first sample is put into the sample chamber, and thermopair arranged on request, thermocouple lead is connected to data acquisition instrument, and data acquisition instrument is plugged on the computing machine, turn-on data Acquisition Instrument and computer system then, so thermopair begins to gather the temperature signal at the position of touching, be communicated with refrigerator sample is lowered the temperature this moment, the simultaneous temperature signal is by data collecting instrument and computer monitoring, after treating that sample freezes fully, stop to gather, utilize calculation procedure of being worked out and the latent heat that freezes that can obtain sample by formula (7).For melting situation, step is as follows: be arranged in thermopair in the sample on request in advance, after treating that sample freezes fully and reaches stable state, semiconductor cooler is applied opposite voltage, while turn-on data Acquisition Instrument and computer system collecting temperature signal, after sample melts fully, stop to gather, utilize calculation procedure of being worked out and the thawing latent heat that can draw sample by formula (7).In the test, the input voltage of semiconductor cooler be can change, thereby different coolings or heating rate obtained.

Claims (11)

1. One kind measure that biological sample freezes or melting process in the method for latent heat, its step is as follows:

   (1) biological sample to be measured is implemented to freeze or melt, to cause the temperature field of variation in sample interior;

   (2) gather in the biological sample temperature field along freezing or melt the transient state solid-state temperature (T that director space each point (x) is located _s) and liquidus temperature (T _l) information;

   (3) the transient temperature information that obtains is inputed to carry out the finite difference data processing in the computing machine, obtain biological sample to be measured along freezing or melt thermograde (the T of direction solid, liquid intersection interface (s) both sides _s/ x), ( T _l/ x), ( T wherein _s/ x) is the thermograde of solid phase one side at the interface, obtains ( T by the space each point finite difference of solid phase one side temperature _l/ x) is the thermograde of liquid phase one side at the interface, obtains by the space each point finite difference of liquid phase one side temperature; Solid phase temperature conductivity (the k of testing sample _s) and liquid phase temperature conductivity (k _l), be known as (K by introducing a thermal conductivity _a) auxiliary heat conduction plain film, in obtaining upper and lower surface of this plain film and plain film one side sample, a bit behind temperature information at place, obtain by the reference method; The rate travel at phase transformation interface (ds/dt) obtains by the different time differences of the interface location (s) of (t) constantly; The energy continuity equation that utilizes tested biological sample solid, liquid intersection interface (s) to locate $L={\frac{(k_s{\&CenterDot;\&PartialD;T}_s/\&PartialD;x-k_l{\&CenterDot;\&PartialD;T}_l/\&PartialD;x)}{\mathrm{ds}/\mathrm{dt}}|}_s,$ Draw the latent heat (L) of biological sample to be measured.
2. 2. mensuration biological sample according to claim 1 freeze or melting process in the method for latent heat, it is characterized in that: described biological sample to be measured is solid-state biological sample or series of liquid biological samples.
3. The described mensuration biological sample of claim 1 freeze or melting process in the measurement mechanism of latent heat of phase change, comprise: refrigerator (c), sample chamber (f), temperature sensor, data collecting instrument and computing machine, the plane refrigerator of described refrigerator (c) for constituting by multistage Peltier semiconductor refrigerating element, its refrigerator (c) is placed sample chamber (f) on the upper surface, the place, lower surface is provided with the heating radiator (b) of band radiated rib, is provided with heat conduction copper sheet (d) between refrigerator (c) and the sample chamber f; Scribble conduction estersil between heat conduction copper sheet (d) and refrigerator (c) and sample chamber (f); Bottom, sample chamber (f) is provided with the known auxiliary plain film (j1) of a thermal conductivity, and the lower surface center position of auxiliary plain film (j1) is embedded with temperature sensor (1); Top, sample chamber (f) is provided with the known auxiliary plain film (j2) of a thermal conductivity, inlays temperature sensor (8) and (9) on its upper and lower surface respectively; Auxiliary plain film (j2) is fixedly connected with the piston (k) that can slide in the vertical through hole of sample chamber upper cover plate; Vertical in the sample chamber (f) 2-7 temperature sensor be set; The lead-in wire of temperature sensor is drawn by the center pit of piston (k), and is connected the input end of data collecting instrument; The input end of data collecting instrument drawn and is connected by the lead-in wire of temperature sensor (1), (8) and (9) by sample chamber (f), the output port of data collecting instrument carries out the finite difference data processing with the transient temperature data that are used for the thermopair input, and the computing machine input port that draws the sample latent heat of phase change links to each other.
4. 4. mensuration biological sample according to claim 3 freeze or melting process in the measurement mechanism of latent heat of phase change, it is characterized in that: described sample chamber (f) sample chamber for being made by glass or organic glass, its inner space is that 10mm * 10mm * 10mm is between 100mm * 100mm * 100mm.
5. According to claim 34 described survey teminal samples freeze or melting process in the measurement mechanism of latent heat of phase change, it is characterized in that: the outer wall of described sample chamber (f) is carved with scale.
6. 6. mensuration biological sample according to claim 3 freeze or melting process in the measurement mechanism of latent heat of phase change, it is characterized in that: sample chamber (f) arranged outside plexiglass tent (e).
7. 7. mensuration biological sample according to claim 3 freeze or melting process in the measurement mechanism of latent heat of phase change, it is characterized in that: the upper surface area of described refrigerator (c) is that 10mm * 10mm is to 100mm * 100mm scope.
8. 8. mensuration biological sample according to claim 3 freeze or melting process in the measurement mechanism of latent heat of phase change, it is characterized in that: the radiated rib of described heating radiator (b) is made by aluminium or copper.
9. 9. mensuration biological sample according to claim 3 freeze or melting process in the measurement mechanism of latent heat of phase change, it is characterized in that: the power supply of described refrigerator (c) is the adjustable adjusting power supply of voltage swing.
10. 10. mensuration biological sample according to claim 3 freeze or melting process in the measurement mechanism of latent heat of phase change, it is characterized in that: the high heat-conducting copper sheet that described refrigerator (c) upper surface covers, its thickness are 0.1 to 2mm.
11. 11. mensuration biological sample according to claim 3 freezes or melting process in the measurement mechanism of latent heat of phase change, it is characterized in that: the auxiliary plain film that auxiliary plain film (j1), (j2) are manufactured for glass or plastics.

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