CN105320841A - Determination method for shower water cooled concrete aggregate transient temperature - Google Patents

Abstract

The present invention provides a determination method for shower water cooled concrete aggregate transient temperature. According to the method provided by the present invention, a convective heat transfer coefficient alpha in in an immersion region considers impacts of shower flow quantity, an aggregate diameter and other factors, and the calculation precision is relatively high; and a falling film convective heat transfer coefficient alpha out in a non-immersion region considers the impacts of the shower flow quantity, a non-immersion aggregate heat transfer area and other factors, and by experimental data calibration, the calculation precision is relatively high. Heat transfer principles are different between the immersion region and the non-immersion region, therefore, the method provided by the invention is more comprehensive and realistic, and conforms to reality. The method provided by the invention considers the influences of a tape printer size, a immersion rate, the shower flow quantity, a void ratio, the aggregate diameter and other factors on the aggregate transient temperature, the scope of application covers all working conditions on a project basically, and the calculating error does not exceed +/- 10%, so that the method is a systematic and complete, accurate and reliable determination method.

Description

A kind of defining method spraying water-cooled aggregate transient temperature

Technical field

The invention belongs to engineering mass transfer, thermal conduction study field, particularly a kind of defining method spraying water-cooled aggregate transient temperature.

Background technology

The object of aggregate precooling, preheating controls concrete placing temperature, prevents watering building body and produce crack.Aggregate precooling, preheating technology have temperature and control the features such as tight, intensity is large, system layout is complicated, are to be related to Hydraulic and Hydro-Power Engineering particularly large water conservancy hydroelectric engineering safety, economic and ensure the key factor of construction speed.

Method conventional in current water-cooled aggregate is spray process.Spray process cooling aggregate generally carries out on belt conveyor (sealing-tape machine), and spray header is arranged in above belt conveyor and carries out water-spraying control to aggregate.Speed belt conveyor spraying cold water cooling aggregate is fast, efficiency is higher, is applicable to heavy construction and large-scale cold aggregate supply.

The unsteady-state heat transfer of shower water cooling aggregate relates to the complex heat transfer process of heterogeneous, on sealing-tape machine aggregate diabatic process and belt speed, to spray the many kinds of parameters such as water temperature, voidage, density relevant.Little at present to the heat transfer process research of spray water-cooled, manyly in engineering predicts temperature after aggregate water-cooled by experience." the pre-refrigeration technique of mass concrete " (Weng Dingbai writes, China Electric Power Publishing House, 2011) the Transient Heat Transfer rule mentioning with single spheroid aggregate under the 3rd class Transfer Boundary Condition (aggregate surface is convection heat transfer condition) carrys out the transient temperature of aggregate in spray Cooling Process on approximate treatment sealing-tape machine.Circular is as described below.

Sealing-tape machine can accumulate shower water in course of conveying, and most of aggregate is immersed in water cooled, and fraction aggregate cools under spray effect.Be immersed in aggregate in water and current when carrying out heat interchange, heat exchange surface is in the third boundary condition of convection heat transfer.The transient state heat transfer process of spheroid under third boundary condition has classical Theory Solution, and the computing method that engineering adopts are:

Finish wet several Bi: $Bi=\frac{\mathrm{\α}R}{\mathrm{\λ}}---\left(1\right)$

Fourier number Fo: $Fo=\frac{a\·\mathrm{\τ}}{R^2}---\left(2\right)$

Dimensionless constant J _i: $J_i=\frac{6{\mathrm{Bi}}^2}{{\mathrm{\μ}}_i^2({\mathrm{\μ}}_i^2+{\mathrm{Bi}}^2-Bi)}---\left(3\right)$

Aggregate medial temperature T: $T=T_a+(T_0-T_a)\·\underset{i=1}{\overset{\mathrm{\∞}}{\Σ}}{J}_i{e}^{-{\mathrm{\μ}}_i^{2}Fo}---\left(4\right)$

In formula, α is the convection transfer rate of aggregate surface, and λ is the coefficient of heat conductivity of aggregate, and R is aggregate radius, and a is aggregate thermal diffusivity, and τ is heat-exchange time, T ₀for aggregate initial temperature, T is the medial temperature after aggregate lasts τ, T _afor spray water temperature, μ _ifor the eigenwert of transient heat conduct equation.

In engineering, convection transfer rate α gets empirical value usually: especially big stone, great Shi (diameter 150-40mm), gets α=116 ~ 58kW/ (m ²dEG C); Middle stone, gravelstone (diameter 40-5mm), get α=35 ~ 12kW/ (m ²dEG C).

As Fo>0.25, formula (4) only can get the Section 1 of progression; When Fo≤0.25, first 6 need be got and just can reach enough accuracy.

According to above-mentioned computing method, under the water-cooled condition that can obtain spraying paint, on belt conveyor, aggregate is in not temperature in the same time.This method is the design and calculation method generally adopted in current water conservancy and hydropower auxiliary enterprises, although this method is simple, has obvious shortcoming:

(1) these computing method are with single spheroid for research object, have ignored the pile up effect of aggregate on sealing-tape machine, are not inconsistent with actual conditions.

(2) in these computing method, convection transfer rate α is that do not consider the impact of the factor such as spray flow, sealing-tape machine volume, value is coarse according to particle size value by rule of thumb.

(3) these computing method represent the transient temperature of all aggregates on sealing-tape machine with the transient temperature of the aggregate be immersed in water, do not consider the transient temperature of the aggregate of non-submergence under spray effect.

(4) the spraying cooling process influence many factors of aggregate, as sealing-tape machine size, submergence degree, spray flow rate, accumulation voidage etc., these computing method all do not consider the impact of these factors, and do not have clear and definite applicable works scope, computational accuracy is not high yet.

Summary of the invention

In order to overcome the problem that error is large and computational accuracy is not high of existing defining method, the invention provides a kind of defining method spraying water-cooled aggregate transient temperature, computational accuracy of the present invention is higher, calculate the transient temperature of non-submergence aggregate under spray effect, and calculates the medial temperature of sealing-tape machine being piled up aggregate according to immersion rate.Submergence district is different from the heat exchange rule of non-submergence district aggregate, thus the present invention more comprehensively, truer, tally with the actual situation, the volume error of calculation of the present invention is no more than ± 10%, be a kind of system comprehensively, defining method accurately and reliably.

The technical solution used in the present invention is:

Spray a defining method for water-cooled aggregate transient temperature, concrete steps are:

1) obtain parameter, calculate Fourier number Fo, measure the diameter d of aggregate, immersion rate η, spray time τ, spray flow m, adhesive tape captain L, adhesive tape machine width W, the external surface area F of non-submergence aggregate, the kinetic viscosity μ of shower water on sealing-tape machine _a, obtain aggregate initial temperature T by temperature sensor ₀, spray water temperature T _a;

2) according to step 1) the middle Fourier number Fo obtained, calculate submergence district aggregate medial temperature T _in, submergence district aggregate medial temperature T _infor:

T _in＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

In formula, Fo is Fourier number, and A, B, C are matching number;

3) according to step 1) middle the Fourier number Fo obtained, aggregate initial temperature T ₀with spray water temperature T _a, calculate non-submergence district aggregate medial temperature T _out, non-submergence district aggregate medial temperature T _outfor:

T _out＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

In formula, Fo is Fourier number, T ₀for aggregate initial temperature, T _afor spray water temperature, A, B, C are matching number;

4) according to the parameter that above-mentioned steps obtains, aggregate medial temperature is calculated, aggregate medial temperature T:

T＝η·T _in+(1-η)·T _out

In formula, T _infor submergence district aggregate medial temperature, T _outfor non-submergence district aggregate medial temperature, η are immersion rate;

5) step 4) in obtain aggregate medial temperature T be placing temperature.

Step 2) in, to be the value of matching number be for A, B, C: the aggregate diameter that the value of A, B, C is different in submergence district, and value is different:

First calculate unit area spray flow G:

$G=\frac{m}{L\×W}$

In formula, m is spray flow, and L is adhesive tape captain, and W is adhesive tape machine width,

Submergence district convection transfer rate α _invalue determined by aggregate diameter,

Aggregate diameter 80-150mm: α _in=91.637G+123.99

Aggregate diameter 40-80mm: α _in=104.05G+76.98

Aggregate diameter 20-40mm: α _in=61.866G+2.0269

Aggregate diameter <20mm: α _in=58.614G+0.8716

By unit area spray flow G and submergence district convection transfer rate α _inobtain submergence district and finish wet several Bi _in: ${\mathrm{Bi}}_{in}=\frac{{\mathrm{\&alpha;}}_{in}d/2}{\mathrm{\&lambda;}},$

The aggregate diameter that the value of A, B, C is different in submergence district, value is:

d＝80～150mm，

A＝-0.0402·Bi _in+1.1223

B＝-0.1554·Bi _in+1.5256

C＝2.5927·Bi _in-2.6824；

d＝40～80mm，

A＝0.0947·Bi _in+0.8355

B＝-0.1955·Bi _in+1.2609

C＝2.6326·Bi _in-0.2936；

d＝20～40mm，

A＝0.2649·Bi _in+0.8891

B＝0.1609·Bi _in+0.7167

C＝5.2176·Bi _in+0.1715；

d＝5～20mm，

A＝0.8367·Bi _in+0.8469

B＝0.1814·Bi _in+0.6758

C＝2.4048·Bi _in+0.0566。

Step 3) in, the aggregate diameter that the value of A, B, C is different in non-submergence district, value is different:

First finish wet several Bi by non-submergence district aggregate group _outcomputing module calculates reynolds number Re;

Non-submergence district spray flow rate Γ:

Reynolds number Re: $\mathrm{Re}=\frac{4\mathrm{\&Gamma;}}{{\mathrm{\&mu;}}_a},$

In formula, m is spray flow, and F is the external surface area of non-submergence aggregate on sealing-tape machine, μ _afor the kinetic viscosity of shower water,

Non-submergence district falling liquid film convection transfer rate α _out:

α _out＝-0.0002·Re ²+0.7112·Re+28.43

By reynolds number Re and non-submergence district falling liquid film convection transfer rate α _outobtain non-submergence district and finish wet several Bi _out: ${\mathrm{Bi}}_{out}=\frac{{\mathrm{\&alpha;}}_{out}d/2}{\mathrm{\&lambda;}}$

The aggregate diameter that the value of A, B, C is different in non-submergence district, value is:

d＝80～150mm，

A＝0.9753·Bi _out ^0.0004

B＝0.9938·Bi _out ^-0.042

C＝6.04·Bi _out ^0.1868；

d＝40～80mm，

A＝0.9957·Bi _out ^-0.001

B＝0.9881·Bi _out ^-0.034

C＝3.9344·Bi _out ^0.3033；

d＝20～40mm，

A＝0.9993·Bi _out ^-0.001

B＝0.9923·Bi _out ^-0.042

C＝2.7837·Bi _out ^0.4146；

d＝0～20mm，

A＝0.9894·Bi _out ^0.0031

B＝0.9363·Bi _out ^-0.025

C＝1.8866·Bi _out ^0.5919。

Step 4) in, the computing method of aggregate medial temperature are:

Submergence district aggregate medial temperature T _in:

T _in＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

Non-submergence district aggregate medial temperature T _out:

T _out＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

Aggregate medial temperature: T=η T _in+ (1-η) T _out

In formula, Fo is Fourier number, Bi _infor submergence district finishes wet number, Bi _outfor non-submergence district finish wet number, d is aggregate diameter, η is immersion rate, T ₀for aggregate initial temperature, T _afor spray water temperature, A, B, C are matching number;

When Fourier number Fo in formula asks for, first ask for the thermal diffusivity of aggregate:

$a=\frac{\mathrm{\&lambda;}}{\mathrm{\&rho;}c}$

Fourier number Fo is calculated again according to the thermal diffusivity of aggregate:

$Fo=\frac{a\mathrm{\&tau;}}{{(d/2)}^2}$

In formula, d is the diameter of aggregate, and λ is aggregate coefficient of heat conductivity, and ρ is the density of aggregate, and c is the specific heat of aggregate, and τ is spray time.

Beneficial effect of the present invention is:

The present invention is with the aggregate group that sealing-tape machine is piled up for research object, but not single aggregate, can calculate the medial temperature of the entirety of not aggregate group in the same time, more tally with the actual situation.

The convection transfer rate α in submergence district in the present invention _inconsider the impact of the factor such as spray flow, aggregate diameter, computational accuracy is higher; The falling liquid film convection transfer rate α in non-submergence district _outconsider the impact of the factor such as spray flow, non-submergence aggregate heat interchanging area, and through the verification of experimental data, computational accuracy is higher.

The present invention calculates the transient temperature of non-submergence aggregate under spray effect, and calculates the medial temperature of sealing-tape machine being piled up aggregate according to immersion rate.Submergence district is different from the heat exchange rule of non-submergence district aggregate, thus the present invention more comprehensively, truer, tally with the actual situation.

The factors such as sealing-tape machine size, immersion rate, spray flow, voidage, aggregate diameter that contemplated by the invention are on the impact of aggregate transient temperature, the scope of application covers operating modes all in engineering substantially, the error of calculation is no more than ± 10%, be a kind of system comprehensively, algorithm accurately and reliably.

Embodiment

Embodiment 1:

In order to overcome the problem that error is large and computational accuracy is not high of existing defining method, the invention provides a kind of defining method spraying water-cooled aggregate transient temperature, computational accuracy of the present invention is higher, calculate the transient temperature of non-submergence aggregate under spray effect, and calculates the medial temperature of sealing-tape machine being piled up aggregate according to immersion rate.Submergence district is different from the heat exchange rule of non-submergence district aggregate, thus the present invention more comprehensively, truer, tally with the actual situation, the volume error of calculation of the present invention is no more than ± 10%, be a kind of system comprehensively, algorithm accurately and reliably.

Spray a defining method for water-cooled aggregate transient temperature, concrete steps are:

1) obtain parameter, calculate Fourier number Fo, measure the diameter d of aggregate, immersion rate η, spray time τ, spray flow m, adhesive tape captain L, adhesive tape machine width W, the external surface area F of non-submergence aggregate, the kinetic viscosity μ of shower water on sealing-tape machine _a, obtain aggregate initial temperature T by temperature sensor ₀, spray water temperature T _a;

2) according to step 1) the middle Fourier number Fo obtained, calculate submergence district aggregate medial temperature T _in, submergence district aggregate medial temperature T _infor:

T _in＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

In formula, Fo is Fourier number, and A, B, C are matching number;

3) according to step 1) middle the Fourier number Fo obtained, aggregate initial temperature T ₀with spray water temperature T _a, calculate non-submergence district aggregate medial temperature T _out, non-submergence district aggregate medial temperature T _outfor:

T _out＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

In formula, Fo is Fourier number, T ₀for aggregate initial temperature, T _afor spray water temperature, A, B, C are matching number;

4) according to the parameter that above-mentioned steps obtains, aggregate medial temperature is calculated, aggregate medial temperature T:

T＝η·T _in+(1-η)·T _out

In formula, T _infor submergence district aggregate medial temperature, T _outfor non-submergence district aggregate medial temperature, η are immersion rate;

5) step 4) in obtain aggregate medial temperature T be placing temperature.

The present invention is the transient temperature defining method of aggregate in the spraying cooling process that obtains of the emulated data by processing hundreds of actual condition, research object is the aggregate group be deposited in sealing-tape machine, be applicable to the width 1.2 ~ 2m of adhesive tape machine width W, unit area spray flow ( ) 0.25 ~ 1kg/m ²s, immersion rate η scope are 0% ~ 100%, the diameter d span of voidage 0.4 ~ 0.5, aggregate is the condition range of 0.003 ~ 0.15m, cover all actual conditions.Emulation mode have passed through experimental check, has very high computational accuracy.

Embodiment 2:

On basis based on embodiment 1, in the present embodiment, step 2) in, to be the value of matching number be for A, B, C: the aggregate diameter that the value of A, B, C is different in submergence district, and value is different:

First calculate unit area spray flow G:

$G=\frac{m}{L\&times;W}$

In formula, m is spray flow, and L is adhesive tape captain, and W is adhesive tape machine width,

Submergence district convection transfer rate α _invalue determined by aggregate diameter,

Aggregate diameter 80-150mm: α _in=91.637G+123.99

Aggregate diameter 40-80mm: α _in=104.05G+76.98

Aggregate diameter 20-40mm: α _in=61.866G+2.0269

Aggregate diameter <20mm: α _in=58.614G+0.8716

By unit area spray flow G and submergence district convection transfer rate α _inobtain submergence district and finish wet several Bi _in: ${\mathrm{Bi}}_{in}=\frac{{\mathrm{\&alpha;}}_{in}d/2}{\mathrm{\&lambda;}},$

The aggregate diameter that the value of A, B, C is different in submergence district, value is:

d＝80～150mm，

A＝-0.0402·Bi _in+1.1223

B＝-0.1554·Bi _in+1.5256

C＝2.5927·Bi _in-2.6824；

d＝40～80mm，

A＝0.0947·Bi _in+0.8355

B＝-0.1955·Bi _in+1.2609

C＝2.6326·Bi _in-0.2936；

d＝20～40mm，

A＝0.2649·Bi _in+0.8891

B＝0.1609·Bi _in+0.7167

C＝5.2176·Bi _in+0.1715；

d＝5～20mm，

A＝0.8367·Bi _in+0.8469

B＝0.1814·Bi _in+0.6758

C＝2.4048·Bi _in+0.0566。

Step 3) in, the aggregate diameter that the value of A, B, C is different in non-submergence district, value is different:

First finish wet several Bi by non-submergence district aggregate group _outcomputing module calculates reynolds number Re;

Non-submergence district spray flow rate Γ:

Reynolds number Re: $\mathrm{Re}=\frac{4\mathrm{\&Gamma;}}{{\mathrm{\&mu;}}_a},$

In formula, m is spray flow, and F is the external surface area of non-submergence aggregate on sealing-tape machine, μ _afor the kinetic viscosity of shower water,

Non-submergence district falling liquid film convection transfer rate α _out:

α _out＝-0.0002·Re ²+0.7112·Re+28.43

By reynolds number Re and non-submergence district falling liquid film convection transfer rate α _outobtain non-submergence district and finish wet several Bi _out: ${\mathrm{Bi}}_{out}=\frac{{\mathrm{\&alpha;}}_{out}d/2}{\mathrm{\&lambda;}}$

The aggregate diameter that the value of A, B, C is different in non-submergence district, value is:

d＝80～150mm，

A＝0.9753·Bi _out ^0.0004

B＝0.9938·Bi _out ^-0.042

C＝6.04·Bi _out ^0.1868；

d＝40～80mm，

A＝0.9957·Bi _out ^-0.001

B＝0.9881·Bi _out ^-0.034

C＝3.9344·Bi _out ^0.3033；

d＝20～40mm，

A＝0.9993·Bi _out ^-0.001

B＝0.9923·Bi _out ^-0.042

C＝2.7837·Bi _out ^0.4146；

d＝0～20mm，

A＝0.9894·Bi _out ^0.0031

B＝0.9363·Bi _out ^-0.025

C＝1.8866·Bi _out ^0.5919。

Step 4) in, the computing method of aggregate medial temperature are:

Submergence district aggregate medial temperature T _in:

T _in＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

Non-submergence district aggregate medial temperature T _out:

T _out＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

Aggregate medial temperature: T=η T _in+ (1-η) T _out

In formula, Fo is Fourier number, Bi _infor submergence district finishes wet number, Bi _outfor non-submergence district finish wet number, d is aggregate diameter, η is immersion rate, T ₀for aggregate initial temperature, T _afor spray water temperature, A, B, C are matching number;

When Fourier number Fo in formula asks for, first ask for the thermal diffusivity of aggregate:

$a=\frac{\mathrm{\&lambda;}}{\mathrm{\&rho;}c}$

Fourier number Fo is calculated again according to the thermal diffusivity of aggregate:

$Fo=\frac{a\mathrm{\&tau;}}{{(d/2)}^2}$

In formula, d is the diameter of aggregate, and λ is aggregate coefficient of heat conductivity, and ρ is the density of aggregate, and c is the specific heat of aggregate, and τ is spray time.

Embodiment 3:

On basis based on embodiment 1, the equal aggregate diameter d in the present invention is less than or equal to 150mm.Introduce the computation process of each step below in detail:

(1) Fourier number Fo computing module

The diameter d of known aggregate, aggregate coefficient of heat conductivity λ, the density p of aggregate, the specific heat c of aggregate, spray time τ.

The thermal diffusivity of aggregate: $a=\frac{\mathrm{\&lambda;}}{\mathrm{\&rho;}c}---\left(5\right)$

Fourier number Fo: $Fo=\frac{a\mathrm{\&tau;}}{{(d/2)}^2}---\left(6\right)$

(2) submergence district aggregate group finishes wet several Bi _incomputing module

After the emulated data of hundreds of operating mode is processed, obtain the convection transfer rate computing method of submergence district aggregate group under different spray flow, different-grain diameter condition, and calculate complete wet several Bi thus _in:

Known spray flow m, adhesive tape captain L, adhesive tape machine width W, the diameter d of aggregate, aggregate coefficient of heat conductivity λ.

Unit area spray flow G: $G=\frac{m}{L\&times;W}---\left(7\right)$

Submergence district convection transfer rate α _in:

Aggregate diameter 80-150mm: α _in=91.637G+123.99 (8)

Aggregate diameter 40-80mm: α _in=104.05G+76.98 (9)

Aggregate diameter 20-40mm: α _in=61.866G+2.0269 (10)

Aggregate diameter <20mm: α _in=58.614G+0.8716 (11)

Submergence district finishes wet several Bi _in: ${\mathrm{Bi}}_{in}=\frac{{\mathrm{\&alpha;}}_{in}d/2}{\mathrm{\&lambda;}}---\left(12\right)$

(3) non-submergence district aggregate group finishes wet several Bi _outcomputing module

Obtain the falling liquid film convection transfer rate computing method of non-submergence district aggregate group under difference spray condition according to the measured data of tens of kinds of operating modes, and calculate complete wet several Bi thus _out:

Known spray flow m, the external surface area F of non-submergence aggregate, the kinetic viscosity μ of shower water on sealing-tape machine _a.

Non-submergence district spray flow rate Γ: $\mathrm{\&Gamma;}=\frac{m}{F}---\left(13\right)$

Reynolds number Re: $\mathrm{Re}=\frac{4\mathrm{\&Gamma;}}{{\mathrm{\&mu;}}_a}---\left(14\right)$

Non-submergence district falling liquid film convection transfer rate α _out:

α _out＝-0.0002·Re ²+0.7112·Re+28.43(15)

Non-submergence district finishes wet several Bi _out: ${\mathrm{Bi}}_{out}=\frac{{\mathrm{\&alpha;}}_{out}d/2}{\mathrm{\&lambda;}}---\left(16\right)$

(4) aggregate transient temperature computing module

Known Fourier number Fo, submergence district finish wet several Bi _in, non-submergence district finishes wet several Bi _out, aggregate diameter d, immersion rate η, aggregate initial temperature T ₀, spray water temperature T _a, then aggregate transient temperature computing method are as follows:

Submergence district aggregate medial temperature T _in:

T _in＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)(17)

Non-submergence district aggregate medial temperature T _out:

T _out＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)(18)

Aggregate medial temperature: T=η T _in+ (1-η) T _out(19)

The calculating of fitting coefficient A, B, C in formula (17), (18) as table 1shown in:

table 1the fit correlation formula of coefficient A, B, C

By formula (17) ~ (19) and table 1, accumulation aggregate under shower water cool condition on sealing-tape machine can be calculated at not medial temperature T in the same time.

The present invention is the transient temperature computing method of aggregate in the spraying cooling process that obtains of the emulated data by processing hundreds of actual condition, research object is the aggregate group be deposited in sealing-tape machine, be applicable to the width 1.2 ~ 2m of adhesive tape machine width W, unit area spray flow ( ) 0.25 ~ 1kg/m ²s, immersion rate η scope are 0% ~ 100%, the diameter d span of voidage 0.4 ~ 0.5, aggregate is the condition range of 0.003 ~ 0.15m, cover all actual conditions.Emulation mode have passed through experimental check, has very high computational accuracy.

The defining method of spray water-cooled aggregate transient temperature fully takes into account the impact of spray flow, immersion rate η heat transfer coefficient, and conventional algorithm calculates the Transient Heat Transfer of aggregate by a certain specific empirical value, and reckon without the pile up effect of aggregate group, so result of calculation has difference.Utilize the defining method of spray water-cooled aggregate transient temperature, calculate two beach concrete constitutive model water-cooled aggregates, system can save water yield 278t/h, and refrigeration duty saves 444kw.The defining method of spray water-cooled aggregate transient temperature is safe and reliable, and it had both decreased part energy consumption, and in turn save equipment component investment, having can promotional value.

Above-mentioned defining method has considered sealing-tape machine size, the factor such as diameter d, spray flow m, heat-exchange time of adhesive tape captain L, voidage, immersion rate η, aggregate is on the impact of aggregate temperature, emulation mode have passed through experimental check, the error of calculation is no more than ± and 10%, be the defining method that a kind of system is comprehensive, computational accuracy is high.

Claims (4)

1. spray a defining method for water-cooled aggregate transient temperature, it is characterized in that: concrete steps are:

1) obtain parameter, calculate Fourier number Fo, measure the diameter d of aggregate, immersion rate η, spray time τ, spray flow m, adhesive tape captain L, adhesive tape machine width W, the external surface area F of non-submergence aggregate, the kinetic viscosity μ of shower water on sealing-tape machine _a, obtain aggregate initial temperature T by temperature sensor ₀, spray water temperature T _a;

2) according to step 1) the middle Fourier number Fo obtained, calculate submergence district aggregate medial temperature T _in, submergence district aggregate medial temperature T _infor:

T _in＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

In formula, Fo is Fourier number, and A, B, C are matching number;

3) according to step 1) middle the Fourier number Fo obtained, aggregate initial temperature T ₀with spray water temperature T _a, calculate non-submergence district aggregate medial temperature T _out, non-submergence district aggregate medial temperature T _outfor:

T _out＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

In formula, Fo is Fourier number, T ₀for aggregate initial temperature, T _afor spray water temperature, A, B, C are matching number;

4) according to the parameter that above-mentioned steps obtains, aggregate medial temperature is calculated, aggregate medial temperature T:

T＝η·T _in+(1-η)·T _out

In formula, T _infor submergence district aggregate medial temperature, T _outfor non-submergence district aggregate medial temperature, η are immersion rate;

5) step 4) in obtain aggregate medial temperature T be placing temperature.

2. a kind of defining method spraying water-cooled aggregate transient temperature according to claim 1, is characterized in that: step 2) in, to be the value of matching number be for A, B, C: the aggregate diameter that the value of A, B, C is different in submergence district, and value is different:

First calculate unit area spray flow G:

$G=\frac{m}{L\&times;W}$

In formula, m is spray flow, and L is adhesive tape captain, and W is adhesive tape machine width,

Submergence district convection transfer rate α _invalue determined by aggregate diameter,

Aggregate diameter 80-150mm: α _in=91.637G+123.99

Aggregate diameter 40-80mm: α _in=104.05G+76.98

Aggregate diameter 20-40mm: α _in=61.866G+2.0269

Aggregate diameter <20mm: α _in=58.614G+0.8716

By unit area spray flow G and submergence district convection transfer rate α _inobtain submergence district and finish wet several Bi _in: ${\mathrm{Bi}}_{in}=\frac{{\mathrm{\&alpha;}}_{in}d/2}{\mathrm{\&lambda;}},$

The aggregate diameter that the value of A, B, C is different in submergence district, value is:

d＝80～150mm，

A＝-0.0402·Bi _in+1.1223

B＝-0.1554·Bi _in+1.5256

C＝2.5927·Bi _in-2.6824；

d＝40～80mm，

A＝0.0947·Bi _in+0.8355

B＝-0.1955·Bi _in+1.2609

C＝2.6326·Bi _in-0.2936；

d＝20～40mm，

A＝0.2649·Bi _in+0.8891

B＝0.1609·Bi _in+0.7167

C＝5.2176·Bi _in+0.1715；

d＝5～20mm，

A＝0.8367·Bi _in+0.8469

B＝0.1814·Bi _in+0.6758

C＝2.4048·Bi _in+0.0566。

3. a kind of defining method spraying water-cooled aggregate transient temperature according to claim 1, is characterized in that: step 3) in, the aggregate diameter that the value of A, B, C is different in non-submergence district, value is different:

First finish wet several Bi by non-submergence district aggregate group _outcomputing module calculates reynolds number Re;

Non-submergence district spray flow rate Γ:

Reynolds number Re: $\mathrm{Re}=\frac{4\mathrm{\&Gamma;}}{{\mathrm{\&mu;}}_a},$

In formula, m is spray flow, and F is the external surface area of non-submergence aggregate on sealing-tape machine, μ _afor the kinetic viscosity of shower water,

Non-submergence district falling liquid film convection transfer rate α _out:

α _out＝-0.0002·Re ²+0.7112·Re+28.43

By reynolds number Re and non-submergence district falling liquid film convection transfer rate α _outobtain non-submergence district and finish wet several Bi _out: ${\mathrm{Bi}}_{out}=\frac{{\mathrm{\&alpha;}}_{out}d/2}{\mathrm{\&lambda;}}$

The aggregate diameter that the value of A, B, C is different in non-submergence district, value is:

d＝80～150mm，

A＝0.9753·Bi _out ^0.0004

B＝0.9938·Bi _out ^-0.042

C＝6.04·Bi _out ^0.1868；

d＝40～80mm，

A＝0.9957·Bi _out ^-0.001

B＝0.9881·Bi _out ^-0.034

C＝3.9344·Bi _out ^0.3033；

d＝20～40mm，

A＝0.9993·Bi _out ^-0.001

B＝0.9923·Bi _out ^-0.042

C＝2.7837·Bi _out ^0.4146；

d＝0～20mm，

A＝0.9894·Bi _out ^0.0031

B＝0.9363·Bi _out ^-0.025

C＝1.8866·Bi _out ^0.5919。

4. a kind of defining method spraying water-cooled aggregate transient temperature according to claim 1, is characterized in that: step 4) in, the computing method of aggregate medial temperature are:

Submergence district aggregate medial temperature T _in:

T _in＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

Non-submergence district aggregate medial temperature T _out:

T _out＝T ₀+[A-B·exp(-1·C·Fo)]·(T _a-T ₀)

Aggregate medial temperature: T=η T _in+ (1-η) T _out

In formula, Fo is Fourier number, Bi _infor submergence district finishes wet number, Bi _outfor non-submergence district finish wet number, d is aggregate diameter, η is immersion rate, T ₀for aggregate initial temperature, T _afor spray water temperature, A, B, C are matching number;

When Fourier number Fo in formula asks for, first ask for the thermal diffusivity of aggregate:

$a=\frac{\mathrm{\&lambda;}}{\mathrm{\&rho;}c}$

Fourier number Fo is calculated again according to the thermal diffusivity of aggregate:

$Fo=\frac{a\mathrm{\&tau;}}{{(d/2)}^2}$

In formula, d is the diameter of aggregate, and λ is aggregate coefficient of heat conductivity, and ρ is the density of aggregate, and c is the specific heat of aggregate, and τ is spray time.