CN102520010B - Condenser dirt detection method for vapor compression cycle cold water unit - Google Patents

Abstract

The invention belongs to the field of heating ventilation air conditioning projects, in particular to a condenser dirt detection method for a vapor compression cycle cold water unit, which includes the following steps: determining and calculating proportional relationship of condenser condensate depression and condenser end difference; calculating condenser end difference without influence of refrigerant charging amount; calculating product of heat exchanger heat transferring coefficient and heat transferring area without influence of refrigerant charging amount; calculating condenser dirt monitoring coefficient; and setting threshold, judging that a condenser has dirt faults and needs to be cleaned when the condenser dirt coefficient is smaller than the threshold. The condenser dirt detection method is accurate and stable in measuring and saves plenty of instrument calibration and maintenance cost compared with a traditional flow meter.

Description

A kind of condenser dirt detection method for the vapor-compression cycle handpiece Water Chilling Units

Technical field

The invention belongs to the HV&AC engineering field, be specifically related to a kind of for monitoring the detection method of handpiece Water Chilling Units Condenser fouling fault.

Background technology

Condenser is the important heat transmission equipment in the central air conditioner water chilling unit system, and its effect is to utilize the chilled water medium to give cooling from the high temperature and high pressure gaseous refrigerant of compressor and to make it to liquefy in condenser.The cooling water recirculation system of handpiece Water Chilling Units mostly is open type system, and because the chilled water medium contacts with atmosphere, the dirts such as dust, microorganism, suspension can inevitably enter cooling water recirculation system and little by little be deposited on the heat exchanger surface of condenser.The dirt of condenser can cause the condenser heat transfer resistance to increase, and heat transfer coefficient descends, and condensing pressure raises, and then causes that the power consumption of compressor increases, and the handpiece Water Chilling Units coefficient of performance reduces.According to pertinent literature statistics, the condenser apparatus expenses that China every year causes due to incrustation scale is up to 600,000,000 yuan of left and right.As can be seen here, Fouling in Condenser on handpiece Water Chilling Units serviceability impact greatly, is detected the Fouling in Condenser fault and the normal operation got rid of for the energy-conservation and system of handpiece Water Chilling Units has great importance in time.

According to the pertinent literature statement, the monitoring for the handpiece Water Chilling Units Fouling in Condenser at present adopts heat resistance method more, and the method can be measured the fouling situation of condenser comparatively exactly, but need to bury thermocouple underground at heat exchanger tube measures the heat exchanger tube wall temperature.Due to the condenser heat-exchange pipes One's name is legion, make the measurement cost of the method high, on engineering, be difficult to realize.And its measurement result is subject to the impact of plugging phenomenon very big.It is a difficult problem in engineering field that the dirt of handpiece Water Chilling Units condenser detects always, and conventional method is difficult to dirt is measured exactly and monitored.

Summary of the invention

Fundamental purpose of the present invention is the above-mentioned deficiency that overcomes prior art, and a kind of detection method that the handpiece Water Chilling Units Condenser fouling fault is monitored is provided.The present invention is based on the measurement value sensor of existing handpiece Water Chilling Units, utilize modeling method to be monitored the fouling fault of condenser.Application of the present invention is the vapor-compression cycle handpiece Water Chilling Units, and its system should comprise evaporator, compressor, shell-and-tube cooler and restriction device.Technical scheme is as follows:

A kind of condenser dirt detection method for the vapor-compression cycle handpiece Water Chilling Units, comprise the following steps:

(1) determine condenser degree of supercooling T _sc;

(2) determine the poor APPR=T of condenser end _c-T _{cond, o}, wherein, T _c: condensing temperature; T _{cond, o}: the condenser cooling water outlet temperature;

(3) calculate condenser degree of supercooling T _scand the proportionate relationship K of the poor APPR of condenser end _{sc, appr}=T _sc/ APPR;

(4) calculate the change Delta T of condenser degree of supercooling _sc=T _sc-T _{sc, rated}, wherein, specified condenser degree of supercooling T _{sc, rated}=a* (T _{cond, o}-T _{cond, i})+b, T _{cond, o}: the condenser cooling water outlet temperature; T _{cond, i}: the condenser cooling water inlet temperature; A and b are the fit equation coefficient, by the matching of different load operating condition of test condition, are determined;

(5) determine that refrigerant charge changes the poor variation of the end APPR caused _ref=Δ T _sc* K _{sc, appr};

(6) calculate the poor APPR of condenser end that has got rid of the refrigerant charge impact ^*=APPR-APPR _ref

(7) heat transfer coefficient of heat exchanger of calculating eliminating refrigerant charge impact and heat transfer area are long-pending ${\mathrm{UA}}^{*}={\stackrel{\·}{m}}_{\mathrm{cond}}\×C_p\×\ln (1+\frac{\mathrm{\ΔT}}{{\mathrm{APPR}}^{*}}),$ Wherein,

the cooling water flow of central air conditioner main machine; C _p: cooling specific heat of water; Δ T: condenser cooling water is imported and exported the temperature difference;

(8) calculate Fouling in Condenser monitoring coefficient VCFMS=UA ^*/ UA _rated, wherein, UA _rated: specified heat transfer coefficient of heat exchanger and heat transfer area are long-pending;

(9) set one and be less than 1 threshold value, when Fouling in Condenser monitoring coefficient VCFMS is less than this threshold value, there is the dirt fault in the judgement condenser, need to be cleaned.

The present invention can be used for the Condenser fouling fault of central air conditioner main machine is monitored.The measurement value sensor of this Fouling in Condenser detecting device based on existing handpiece Water Chilling Units, utilize the method for modeling to be monitored the fouling fault of condenser.Fouling measuring method of the present invention has following outstanding feature:

(1) experiment show the method can be accurately, stably the Fouling in Condenser fault is detected;

(2) the method is based on the existing measurement value sensor of handpiece Water Chilling Units, and the mode that adopts virtual dirt to detect is monitored the Fouling in Condenser fault, with traditional dirt detecting method, compares and has saved a large amount of equipment costs;

(3) the method is easy to realize, has very high engineering using value.

The accompanying drawing explanation

Fig. 1 central air conditioner handpiece Water Chilling Units cooling cycle system figure.

Embodiment

Fig. 1 is a typical central air-conditioner host Vapor Compression Refrigeration Cycle system 10.System 10 comprises chilled water/air circulation system 20 and the chilled water circulation system 22.Enter condenser 14 after refrigerant vapour during refrigeration system work in compressor 12 suction evaporators 18 is compressed.Cold-producing medium is cooled to liquid in equipressure under condensing pressure, and during condensation of refrigerant, liberated heat is passed to heat eliminating medium water/air.Condensed liquid enters evaporator 18 by restriction device 16.Cold-producing medium seethes with excitement under evaporating pressure, with chilled water, carries out heat exchange.

As shown in Figure 1, being applicable to central air conditioner handpiece Water Chilling Units of the present invention should comprise with lower sensor: condensator outlet refrigerant temperature T _ll34, condensing temperature T _c40, cooling water inlet temperature T _{cond, i}32, cooling water outlet temperature T _{cond, o}the cooling water flow of 30 central air conditioner handpiece Water Chilling Units

Fouling in Condenser detecting device of the present invention is realized by following concrete technical scheme:

(1) at first determine and at first utilize the delivery test data of water chilling unit host or in-site measurement experimental data to determine condenser degree of supercooling T _scand the proportionate relationship (K of the poor APPR of condenser end _{sc, appr}.Condenser degree of supercooling T wherein _scby following formula, determined:

T _sc＝T _c-T _ll (1)

The poor APPR of condenser end is determined by equation (2):

APPR＝T _c-T _cond，o (2)

Proportionate relationship (K _{sc, appr}) by equation (3), determined:

K _sc，appr＝T _sc/APPR (3)

In equation, parameter interpretation used is as follows:

T _sc: the condenser degree of supercooling;

T _ll: condensator outlet refrigerant temperature 34;

T _c: condensing temperature 40

APPR: condenser end is poor

T _{cond, o}: condenser cooling water outlet temperature 30

(2) according to the determined condenser degree of supercooling of step 1 T _scand the proportionate relationship (K of the poor APPR of condenser end _{sc, appr}) the system refrigerant charging amount is changed to the poor impact on condenser end predicted square journey (4).The charging amount of cold-producing medium changes can pass through the change Delta T of condenser degree of supercooling _scsecondary indication.

APPR _ref＝ΔT _sc*K _sc，appr (4)

ΔT _sc＝T _sc-T _sc，rated (5)

Specified condenser degree of supercooling T in equation 5 _{sc, rated}can be determined by equation (6):

T _sc，rated＝a*(T _cond，o-T _cond，i)+b (6)

In above-mentioned equation, parameter interpretation used is as follows:

APPR _ref: refrigerant charge changes the poor variation of end caused;

Δ T _sc: the condenser degree of supercooling changes;

T _{sc, rated}: specified condenser degree of supercooling;

T _{cond, o}: condenser cooling water outlet temperature 30;

T _{cond, i}: condenser cooling water inlet temperature 32;

A and b: the fit equation coefficient, this coefficient can be by determining that matching obtains by the test figure under different load operating condition of test condition.

(3) charging amount that utilizes equation 7 to get rid of cold-producing medium changes the impact poor on condenser end

APPR ^*＝APPR-APPR _ref (7)

(4) utilizing equation (8) and equation (9) to set up the Fouling in Condenser detection model according to heat transfer principle is monitored the Fouling in Condenser fault

${\mathrm{UA}}^{*}={\stackrel{\·}{m}}_{\mathrm{cond}}\×C_p\×\ln (1+\frac{\mathrm{\ΔT}}{{\mathrm{APPR}}^{*}})---\left(8\right)$

VCFMS＝UA ^*/UA _rated (9)

In equation, parameter interpretation used is as follows:

the cooling water flow 36 of central air conditioner main machine;

C _p: cooling specific heat of water;

Δ T: condenser cooling water is imported and exported the temperature difference

APPR ^*: the condenser end of getting rid of the refrigerant charge impact is poor

UA ^*: heat transfer coefficient of heat exchanger and the heat transfer area of getting rid of the refrigerant charge impact are long-pending

UA: heat transfer coefficient of heat exchanger and heat transfer area are long-pending

UA _rated: specified heat transfer coefficient of heat exchanger and heat transfer area are long-pending

VCFMS: Fouling in Condenser monitoring coefficient

The long-pending UA of specified heat transfer coefficient of heat exchanger and heat transfer area _ratedcan be determined by the test figure under different load operating condition of test condition.

(5) to equation (9), definite Fouling in Condenser monitoring coefficient VCFMS is estimated, when being less than one, Fouling in Condenser monitoring coefficient VCFMS is not more than 1 threshold value,, can judge that there is the dirt fault in condenser, and then the suggestion user is cleaned to condenser at for example 0.8 o'clock.

Claims (1)

1. the condenser dirt detection method for the vapor-compression cycle handpiece Water Chilling Units, comprise the following steps:

(1) determine condenser degree of supercooling T _sc;

(2) determine the poor APPR=T of condenser end _c-T _{cond, o}, wherein, T _c: condensing temperature; T _{cond, o}: the condenser cooling water outlet temperature;

(3) calculate condenser degree of supercooling T _scand the proportionate relationship K of the poor APPR of condenser end _{sc, appr}=T _sc/ APPR;

(4) calculate the change Delta T of condenser degree of supercooling _sc=T _sc-T _{sc, rated}, wherein, specified condenser degree of supercooling T _{sc, rated}=a* (T _{cond, o}-T _{cond, i})+b, T _{cond, o}: the condenser cooling water outlet temperature; T _{cond, i}: the condenser cooling water inlet temperature; A and b are the fit equation coefficient, by the matching of different load operating condition of test condition, are determined;

(5) determine that refrigerant charge changes the poor variation of the end APPR caused _ref=Δ T _sc* K _{sc, appr};

(6) calculate the poor APPR of condenser end that has got rid of the refrigerant charge impact ^*=APPR-APPR _ref

(7) heat transfer coefficient of heat exchanger of calculating eliminating refrigerant charge impact and heat transfer area are long-pending $U{A}^{*}={\stackrel{.}{m}}_{\mathrm{cond}}*C_p*\ln (1+\frac{\mathrm{\ΔT}}{\mathrm{APP}{R}^{*}})$ Wherein,

: the cooling water flow of central air conditioner main machine; C _p: cooling specific heat of water; Δ T: condenser cooling water is imported and exported the temperature difference;

(8) calculate Fouling in Condenser monitoring coefficient VCFMS=UA ^*/ UA _rated, wherein, UA _rated: specified heat transfer coefficient of heat exchanger and heat transfer area are long-pending;

(9) set one and be less than 1 threshold value, when Fouling in Condenser monitoring coefficient VCFMS is less than this threshold value, there is the dirt fault in the judgement condenser, need to be cleaned.

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