CN102359976A - Device and method for detecting heat radiation performance stability of automobile air conditioner heat exchanger - Google Patents

Abstract

The invention discloses a device and a method for detecting the heat radiation performance stability of an automobile air conditioner heat exchanger. A constant-temperature water tank is connected with a water inlet of a high-temperature-resistance safe water pump through a water quantity regulation valve and is simultaneously connected with the outlet end of the heat exchanger, a water outlet of the water pump is connected with the inlet end of the heat exchanger through a flow rate meter, and a plurality of temperature sensors are placed around the heat exchanger and are connected with a data processing center after being connected with a data collecting system. A fan is placed right in front of the windward side of the heat exchanger. The constant-temperature water tank provides constant hot water, the water pump boosts the pressure of hot water, the temperature sensors test the temperature of the water and the air after and before passing through the heat exchanger, the flow rate meter measures the flow rate of the water while passing through the heat exchanger, the fan simulates the actual work state, the data collecting system converts signals collected by the temperature sensors and the flow rate meter into data, and the data processing center analyzes the collected data and obtains the heat transfer factor and the heat radiation performance stability results of the heat exchanger. The device and the method can be used for detecting the heat radiation performance stability of the automobile air conditioner heat exchanger, and the detection is reliable.

Description

A kind of apparatus and method of air conditioning for automobiles heat interchanger heat dispersion Detection of Stability

Technical field

The present invention relates to a kind of apparatus and method of heat interchanger heat dispersion stability, especially relate to a kind of apparatus and method of air conditioning for automobiles heat interchanger heat dispersion Detection of Stability.

Background technology

The air conditioning for automobiles heat interchanger is the equipment with the part heat transferred cold fluid of hot fluid, is the important component part of automotive air-conditioning system.Heat exchange property is an important indicator weighing air conditioning for automobiles heat interchanger quality; Heat exchange property stability will be directly connected to the effect of heat interchanger work; If this index does not reach the regulation requirement; With the heat exchange effect that has a strong impact on heat interchanger, therefore be badly in need of the pick-up unit and the method for a detection heat interchanger heat exchange property.The liquid coolant that existing heat interchanger heat exchange property test is used mainly is a freon; The test data item is various; This impermeability and structural requirement to whole device is very high, and behind the EOT, freon residual in the heat interchanger also can pollute atmosphere; This method complicated operation of while, cost costliness, and the external product of dependable performance also usually receives blockade on new techniques.Therefore press for a kind of apparatus and method of simple and easy, eco-friendly air conditioning for automobiles heat interchanger heat dispersion Detection of Stability.

Summary of the invention

For overcoming the problem that exists in the background technology; The object of the present invention is to provide a kind of apparatus and method of air conditioning for automobiles heat interchanger heat dispersion Detection of Stability, make water as liquid coolant, performance test can not cause any pollution after finishing; And simple to operate, need the data measured item few.Use the calculating of thermodynamics formula, draw the heat transfer coefficient of heat interchanger,, reach heat dispersion Detection of Stability purpose through analysis to heat transfer coefficient.

The technical scheme that the present invention adopts is:

One, a kind of device of air conditioning for automobiles heat interchanger heat dispersion Detection of Stability:

Comprise constant temperature water tank, water regulating valve, high temperature resistant safe water pump, flowmeter, fan, a plurality of temperature sensor, data acquisition system (DAS), data processing centre (DPC) and display; Constant temperature water tank links to each other with the water inlet of high temperature resistant safe water pump through water regulating valve, and constant temperature water tank links to each other with the heat exchanger exit end; The water delivering orifice of high temperature resistant safe water pump links to each other with the heat interchanger entrance point through flowmeter; A plurality of temperature sensors are placed on the heat exchanger inlet and outlet end respectively and the windward side is just preceding and the dead astern is the air inlet face and the face of giving vent to anger, and flowmeter links to each other with data acquisition system (DAS) through data line with temperature sensor; Data acquisition system (DAS) connects display through data processing centre (DPC); Fan is placed on the dead ahead of heat interchanger windward side; Constant temperature water tank, high temperature resistant safe water pump, flowmeter, fan, data acquisition system (DAS), data processing centre (DPC) and display all connect AC power.

The medium temperature scope of described high temperature resistant safe water pump is 0 ℃～110 ℃, and H-Max is more than or equal to 30m.

Described temperature sensor is eight, and one is arranged on the heat interchanger entrance point, and one is arranged on the heat exchanger exit end, and three are arranged on dead ahead, heat interchanger windward side is air inlet face, and three are arranged on dead astern, the heat interchanger windward side face of promptly giving vent to anger.

Described temperature sensor is thermopair, thermistor, resistance temperature detector or IC temperature sensor, and temperature-measuring range is 0 ℃～110 ℃.

Described flow is counted turbo flow meter, electromagnetic flowmeter or ultrasonic flow meter.

Two, a kind of method of air conditioning for automobiles heat interchanger heat dispersion Detection of Stability, it comprises following step:

1) heat interchanger is vertically placed, eight temperature sensors, one is arranged on the heat interchanger entrance point, and one is arranged on the heat exchanger exit end, and three are arranged on dead ahead, heat interchanger windward side is air inlet face, and three are arranged on dead astern, the heat interchanger windward side face of promptly giving vent to anger;

2) open constant temperature water tank, design temperature is 60 ℃～80 ℃;

3) adjustable valve of fetching boiling water is opened high temperature resistant safe water pump, and water is got back to constant temperature water tank from flow through water regulating valve, high temperature resistant safe water pump, flowmeter, heat interchanger of constant temperature water tank;

4) fan is installed in dead ahead, heat interchanger windward side, opens fan and quickens heat radiation;

5) eight temperature sensors link to each other with data acquisition system (DAS) through data line with flowmeter; Data acquisition system (DAS) links to each other through data line with data processing centre (DPC); Turn-on data acquisition system and data processing centre (DPC) are provided with temperature sensor and the flow meter data acquisition time is spaced apart 10 seconds;

6) treat that water temperature and discharge are stable after, send instruction beginning image data through data processing centre (DPC);

7) the heat interchanger entrance point discharge that collects according to data acquisition system (DAS) of data processing centre (DPC), the entrance point water temperature, the endpiece water temperature, the air inlet face temperature, the area of dissipation of give vent to anger surface temperature and tested heat interchanger calculates heat transfer coefficient;

If recording certain moment heat interchanger entrance point discharge is V (m ³/ s), the entrance point water temperature is t ₁(℃), the endpiece water temperature is t ₂(℃), the temperature of three points of air inlet face is t ₃₁(℃), t ₃₂(℃), t ₃₃(℃), the temperature of three points of face of giving vent to anger is t ₄₁(℃), t ₄₂(℃), t ₄₃(℃).

The temperature difference of heat exchanger inlet and outlet end water be Δ t (℃)

Δt＝t ₁-t ₂

Heat interchanger air inlet face medial temperature is t ₃(℃)

$t_3=\frac{t_{31}+t_{32}+t_{33}}{3}$

The heat interchanger face medial temperature of giving vent to anger is t ₄(℃)

$t_4=\frac{t_{41}+t_{42}+t_{43}}{3}$

The mean logarithmic temperature difference of air and water is Δ t _m(℃)

$\mathrm{\Δ}{t}_m=\frac{(t_1-t_2)-(t_2-t_4)}{\ln \frac{l_1-l_3}{l_2-l_4}}$

If specific heat of water is c [J/Kg a ℃], the density of water is ρ (Kg/m ³), then this mass rate that flows through the water of heat interchanger constantly is M (kg/s)

M＝ρV

This moment water liberated heat is Q _Water(W),

Q _Water=cM Δ t=cpV Δ t

If the heat transfer coefficient of heat interchanger is K [W/ (m ²℃)], heat transfer area is A (m ²), then the heat taken away of this moment heat interchanger is Q _{Heat interchanger}(W)

Q _{Heat interchanger}=KA Δ t _m

According to law of conservation of energy,

Q _{Heat interchanger}=Q _Water

Equality with above the various substitution obtains

KAΔt _m＝cρVΔt

Arrangement obtains the computing formula of K:

$K=\frac{3\mathrm{c\ρV}(t_1-t_2)\ln \frac{3t_1-t_{31}-t_{32}-t_{33}}{{3t}_2-t_{41}-t_{42}-t_{43}}}{A({3t}_1+t_{41}+t_{42}+t_{43}-{3t}_2-t_{31}-t_{32}-t_{33})}$

With the V that records, t ₁, t ₂, t ₃₁, t ₃₂, t ₃₃, t ₄₁, t ₄₂, t ₄₃, A that calculates and constant c, ρ substitution following formula just can obtain the K value;

8) data processing centre (DPC) draws quality control chart according to the heat transfer coefficient that calculates, and prescribes a time limit when heat transfer coefficient exceeds the upper limit or is lower than down, and system gives the alarm;

If moment T _iThe heat transfer coefficient that the data computation that collects obtains is K _i(i=1,2,3 ..., n), K _iMean value do

$\stackrel{\‾}{K}=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{K}_i}{n}$

K _iStandard deviation be S

$S=\sqrt{\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(K_i-\stackrel{\‾}{K})}^2}{n}}$

According to the X control chart, can draw:

Control central line

UCL $\mathrm{UCL}=\stackrel{\‾}{K}+3S$

Lower control limit $\mathrm{LCL}=\stackrel{\‾}{K}-3S$

When the K value exceeded UCL or is lower than LCL, system gave the alarm, and shows that the heat interchanger heat dispersion has been in the non-statistical state of a control, and promptly unstable situation appears in the radiator heat-dissipation performance.

The beneficial effect that the present invention has is:

The present invention can carry out the stability test to air conditioning for automobiles heat interchanger heat dispersion, can detect and verify the reliability of air conditioning for automobiles heat interchanger, simple in structure, easy to manufacture, Operation and maintenance convenience, and environmental protection is reliable.

Description of drawings

Accompanying drawing is the schematic diagram of pick-up unit of the present invention.

Among the figure: 1, constant temperature water tank, 2, water regulating valve, 3, high temperature resistant safe water pump, 4, flowmeter, 5, water pipe, 6, fan, 7, temperature sensor, 8, heat interchanger, 9, data acquisition system (DAS), 10, data processing centre (DPC), 11, display.

Embodiment

Below in conjunction with Figure of description and case study on implementation the present invention is further described.

Shown in accompanying drawing, comprise constant temperature water tank 1, water regulating valve 2, high temperature resistant safe water pump 3, flowmeter 4, water pipe 5, fan 6, a plurality of temperature sensor 7, tested heat interchanger 8, data acquisition system (DAS) 9, data processing centre (DPC) 10 and display 11; Constant temperature water tank 1 links to each other through the water inlet of water regulating valve 2 with high temperature resistant safe water pump 3, and constant temperature water tank 1 links to each other with heat interchanger 8 endpiece; The water delivering orifice of high temperature resistant safe water pump 3 links to each other with the heat interchanger entrance point through flowmeter 4; A plurality of temperature sensors are placed on heat interchanger 8 entrance ends and positive front and back respectively, and flowmeter 4 links to each other with data acquisition system (DAS) 9 through data line with temperature sensor 7; Data acquisition system (DAS) 9 connects display 11 through data processing centre (DPC) 10; Fan 6 is placed on the dead ahead of heat interchanger 8 windward sides; Constant temperature water tank 1, high temperature resistant safe water pump 3, flowmeter 4, fan 6, data acquisition system (DAS) 9, data processing centre (DPC) 10 and display 11 all connect AC power.Solid line is water pipe 5 in the accompanying drawing, and solid arrow is represented the flow direction of water, and dotted line is a data line, and dotted arrow is represented the transmission direction of data.

The medium temperature scope of described high temperature resistant safe water pump 3 is 0 ℃～110 ℃, and H-Max is more than or equal to 30m.

Described temperature sensor 7 is eight, and one is arranged on the heat interchanger entrance point, and one is arranged on the heat exchanger exit end, and three are arranged on dead ahead, heat interchanger windward side is air inlet face, and three are arranged on dead astern, the heat interchanger windward side face of promptly giving vent to anger.

Described temperature sensor 7 is thermopair, thermistor, resistance temperature detector or IC temperature sensor, and temperature-measuring range is 0 ℃～110 ℃.

Described flowmeter 4 is turbo flow meter, electromagnetic flowmeter or ultrasonic flow meter.

The all water pipes 5 of the present invention are the hot water leather hose, and the bearing temperature scope is 0 ℃～110 ℃.

Water has high-temperature and high pressure through the pressurization of constant temperature water tank 1 heating with high temperature resistant safe water pump 3, and the heat interchanger of flowing through is got back to constant temperature water tank 1, realizes the recycle of water.In the process of heat interchanger 8 heat exchange; The heat that heat interchanger 8 is taken away equals the heat that water self reduces; Measure the entrance end temperature that current are measured through the flow and the temperature sensor 7 of heat interchanger 8 through flowmeter 4; The temperature of heat interchanger 8 front and back air can be calculated the heat that water self reduces, and then draw the heat that heat interchanger 8 is taken away.Data processing centre (DPC) 10 draws the heat transfer coefficient of heat interchanger 8 with the heat transfer formula of the heat transfer area substitution heat interchanger of data that record and heat interchanger self.The analysis heat transfer coefficient obtains heat interchanger 8 heat dispersion stability result and is shown on the display 11, will give the alarm if any abnormal results.

Method of the present invention comprises following step:

1) heat interchanger is vertically placed, eight temperature sensors, one is arranged on the heat interchanger entrance point, and one is arranged on the heat exchanger exit end, and three are arranged on dead ahead, heat interchanger windward side, and three are arranged on dead astern, heat interchanger windward side;

2) in constant temperature water tank, add a certain amount of water, open constant temperature water tank, design temperature is 60 ℃～80 ℃, and when the temperature of water in the constant temperature water tank 1 was lower than 80 ℃, heating arrangement started automatically, when the temperature of water surpasses 80 ℃, and the heating arrangement automatic pause;

3) adjustable valve of fetching boiling water is opened high temperature resistant safe water pump, and water is got back to constant temperature water tank from flow through water regulating valve, high temperature resistant safe water pump, flowmeter, heat interchanger of constant temperature water tank;

4) fan is installed in dead ahead, heat interchanger windward side, opens fan and quickens heat radiation;

5) eight temperature sensors link to each other with data acquisition system (DAS) through data line with flowmeter; Data acquisition system (DAS) links to each other through data line with data processing centre (DPC); Turn-on data acquisition system and data processing centre (DPC) are provided with temperature sensor and the flow meter data acquisition time is spaced apart 10 seconds;

6) treat that water temperature and discharge are stable after, send instruction beginning image data through data processing centre (DPC);

7) the heat interchanger entrance point discharge that collects according to data acquisition system (DAS) of data processing centre (DPC), the entrance point water temperature, the endpiece water temperature, the air inlet face temperature, the area of dissipation of give vent to anger surface temperature and tested heat interchanger calculates heat transfer coefficient;

If recording certain moment heat interchanger entrance point discharge is V (m ³/ s), the entrance point water temperature is t ₁(℃), the endpiece water temperature is t ₂(℃), the temperature of three points of air inlet face is t ₃₁(℃), t ₃₂(℃), t ₃₃(℃), the temperature of three points of face of giving vent to anger is t ₄₁(℃), t ₄₂(℃), t ₄₃(℃).

The temperature difference of heat exchanger inlet and outlet end water be Δ t (℃)

Δt＝t ₁-t ₂

Heat interchanger air inlet face medial temperature is t ₃(℃)

$t_3=\frac{t_{31}+t_{32}+t_{33}}{3}$

The heat interchanger face medial temperature of giving vent to anger is t ₄(℃)

$t_4=\frac{t_{41}+t_{42}+t_{43}}{3}$

The mean logarithmic temperature difference of air and water is Δ t _m(℃)

$\mathrm{\Δ}{t}_m=\frac{(t_1-t_2)-(t_2-t_4)}{\ln \frac{l_1-l_3}{l_2-l_4}}$

If specific heat of water is c [J/Kg a ℃], the density of water is ρ (Kg/m ³), then this mass rate that flows through the water of heat interchanger constantly is M (kg/s)

M＝ρV

This moment water liberated heat is Q _Water(W),

Q _Water=cM Δ t=cpV Δ t

If the heat transfer coefficient of heat interchanger is K [W/ (m ²℃)], heat transfer area is A (m ²), then the heat taken away of this moment heat interchanger is Q _{Heat interchanger}(W)

Q _{Heat interchanger}=KA Δ t _m

According to law of conservation of energy,

Q _{Heat interchanger}=Q _Water

Equality with above the various substitution obtains

KAΔt _m＝cρVΔt

Arrangement obtains the computing formula of K:

$K=\frac{3\mathrm{c\ρV}(t_1-t_2)\ln \frac{3t_1-t_{31}-t_{32}-t_{33}}{{3t}_2-t_{41}-t_{42}-t_{43}}}{A({3t}_1+t_{41}+t_{42}+t_{43}-{3t}_2-t_{31}-t_{32}-t_{33})}$

With the V that records, t ₁, t ₂, t ₃₁, t ₃₂, t ₃₃, t ₄₁, t ₄₂, t ₄₃, A that calculates and constant c, ρ substitution following formula just can obtain the K value;

8) data processing centre (DPC) draws quality control chart according to the heat transfer coefficient that calculates, and prescribes a time limit when heat transfer coefficient exceeds the upper limit or is lower than down, and system gives the alarm;

If moment T _iThe heat transfer coefficient that the data computation that collects obtains is K _i(i=1,2,3 ..., n), K _iMean value do

$\stackrel{\‾}{K}=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{K}_i}{n}$

K _iStandard deviation be S

$S=\sqrt{\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(K_i-\stackrel{\‾}{K})}^2}{n}}$

According to the X control chart, can draw:

Control central line

UCL $\mathrm{UCL}=\stackrel{\‾}{K}+3S$

Lower control limit $\mathrm{LCL}=\stackrel{\‾}{K}-3S$

When the K value exceeded UCL or is lower than LCL, system gave the alarm, and shows that the heat interchanger heat dispersion has been in the non-statistical state of a control, and promptly unstable situation appears in the radiator heat-dissipation performance.

Claims (6)

1. the device of an air conditioning for automobiles heat interchanger heat dispersion Detection of Stability is characterized in that: comprise constant temperature water tank (1), water regulating valve (2), high temperature resistant safe water pump (3), flowmeter (4), fan (6), a plurality of temperature sensor (7), data acquisition system (DAS) (9), data processing centre (DPC) (10) and display (11); Constant temperature water tank (1) links to each other through the water inlet of water regulating valve (2) with high temperature resistant safe water pump (3), and constant temperature water tank (1) links to each other with heat interchanger (8) endpiece; The water delivering orifice of high temperature resistant safe water pump (3) links to each other with the heat interchanger entrance point through flowmeter (4); A plurality of temperature sensors are placed on heat interchanger (8) entrance end respectively and the windward side is just preceding and the dead astern is the air inlet face and the face of giving vent to anger, and flowmeter (4) links to each other with data acquisition system (DAS) (9) through data line with temperature sensor (7); Data acquisition system (DAS) (9) connects display (11) through data processing centre (DPC) (10); Fan (6) is placed on the dead ahead of heat interchanger (8) windward side; Constant temperature water tank (1), high temperature resistant safe water pump (3), flowmeter (4), fan (6), data acquisition system (DAS) (9), data processing centre (DPC) (10) and display (11) all connect AC power.

2. the device of a kind of air conditioning for automobiles heat interchanger heat dispersion Detection of Stability according to claim 1 is characterized in that: the medium temperature scope of described high temperature resistant safe water pump (3) is 0 ℃～110 ℃, and H-Max is more than or equal to 30m.

3. the device of a kind of air conditioning for automobiles heat interchanger heat dispersion Detection of Stability according to claim 1; It is characterized in that: described temperature sensor (7) is eight; One is arranged on the heat interchanger entrance point; One is arranged on the heat exchanger exit end, and three are arranged on dead ahead, heat interchanger windward side is air inlet face, and three are arranged on dead astern, the heat interchanger windward side face of promptly giving vent to anger.

4. the device of a kind of air conditioning for automobiles heat interchanger heat dispersion Detection of Stability according to claim 1; It is characterized in that: described temperature sensor (7) is thermopair, thermistor, resistance temperature detector or IC temperature sensor, and temperature-measuring range is 0 ℃～110 ℃.

5. the device of a kind of air conditioning for automobiles heat interchanger heat dispersion Detection of Stability according to claim 1 is characterized in that: described flowmeter (4) is turbo flow meter, electromagnetic flowmeter or ultrasonic flow meter.

6. according to the method for a kind of air conditioning for automobiles heat interchanger heat dispersion Detection of Stability of the said device of claim 1, it is characterized in that it comprises following step:

1) heat interchanger is vertically placed, eight temperature sensors, one is arranged on the heat interchanger entrance point, and one is arranged on the heat exchanger exit end, and three are arranged on dead ahead, heat interchanger windward side is air inlet face, and three are arranged on dead astern, the heat interchanger windward side face of promptly giving vent to anger;

2) open constant temperature water tank, design temperature is 60 ℃～80 ℃;

3) adjustable valve of fetching boiling water is opened high temperature resistant safe water pump, and water is got back to constant temperature water tank from flow through water regulating valve, high temperature resistant safe water pump, flowmeter, heat interchanger of constant temperature water tank;

4) fan is installed in dead ahead, heat interchanger windward side, opens fan and quickens heat radiation;

5) eight temperature sensors link to each other with data acquisition system (DAS) through data line with flowmeter; Data acquisition system (DAS) links to each other through data line with data processing centre (DPC); Turn-on data acquisition system and data processing centre (DPC) are provided with temperature sensor and the flow meter data acquisition time is spaced apart 10 seconds;

6) treat that water temperature and discharge are stable after, send instruction beginning image data through data processing centre (DPC);

7) the heat interchanger entrance point discharge that collects according to data acquisition system (DAS) of data processing centre (DPC), the entrance point water temperature, the endpiece water temperature, the air inlet face temperature, the area of dissipation of give vent to anger surface temperature and tested heat interchanger calculates heat transfer coefficient;

If recording certain moment heat interchanger entrance point discharge is V (m ³/ s), the entrance point water temperature is t ₁(℃), the endpiece water temperature is t ₂(℃), the temperature of three points of air inlet face is t ₃₁(℃), t ₃₂(℃), t ₃₃(℃), the temperature of three points of face of giving vent to anger is t ₄₁(℃), t ₄₂(℃), t ₄₃(℃).

The temperature difference of heat exchanger inlet and outlet end water be Δ t (℃)

Δt＝t ₁-t ₂

Heat interchanger air inlet face medial temperature is t ₃(℃)

$t_3=\frac{t_{31}+t_{32}+t_{33}}{3}$

The heat interchanger face medial temperature of giving vent to anger is t ₄(℃)

$t_4=\frac{t_{41}+t_{42}+t_{43}}{3}$

The mean logarithmic temperature difference of air and water is Δ t _m(℃)

$\mathrm{\Δ}{t}_m=\frac{(t_1-t_2)-(t_2-t_4)}{\ln \frac{l_1-l_3}{l_2-l_4}}$

If specific heat of water is c [J/Kg a ℃], the density of water is ρ (Kg/m ³), then this mass rate that flows through the water of heat interchanger constantly is M (kg/s)

M＝ρV

This moment water liberated heat is Q _Water(W),

Q _Water=cM Δ t=cpV Δ t

If the heat transfer coefficient of heat interchanger is K [W/ (m ²℃)], heat transfer area is A (m ²), then the heat taken away of this moment heat interchanger is Q _{Heat interchanger}(W)

Q _{Heat interchanger}=KA Δ t _m

According to law of conservation of energy,

Q _{Heat interchanger}=Q _Water

Equality with above the various substitution obtains

KAΔt _m＝cρVΔt

Arrangement obtains the computing formula of K:

$K=\frac{3\mathrm{c\ρV}(t_1-t_2)\ln \frac{3t_1-t_{31}-t_{32}-t_{33}}{{3t}_2-t_{41}-t_{42}-t_{43}}}{A({3t}_1+t_{41}+t_{42}+t_{43}-{3t}_2-t_{31}-t_{32}-t_{33})}$

With the V that records, t ₁, t ₂, t ₃₁, t ₃₂, t ₃₃, t ₄₁, t ₄₂, t ₄₃, A that calculates and constant c, ρ substitution following formula just can obtain the K value;

8) data processing centre (DPC) draws quality control chart according to the heat transfer coefficient that calculates, and prescribes a time limit when heat transfer coefficient exceeds the upper limit or is lower than down, and system gives the alarm;

If moment T _iThe heat transfer coefficient that the data computation that collects obtains is K _i(i=1,2,3 ..., n), K _iMean value do

$\stackrel{\‾}{K}=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{K}_i}{n}$

K _iStandard deviation be S

$S=\sqrt{\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(K_i-\stackrel{\‾}{K})}^2}{n}}$

According to the X control chart, can draw:

Control central line

UCL $\mathrm{UCL}=\stackrel{\‾}{K}+3S$

Lower control limit $\mathrm{LCL}=\stackrel{\‾}{K}-3S$

When the K value exceeded UCL or is lower than LCL, system gave the alarm, and shows that the heat interchanger heat dispersion has been in the non-statistical state of a control, and promptly unstable situation appears in the radiator heat-dissipation performance.

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