CN101029881B - Method for measuring and controlling assembled air-conditioner dew point - Google Patents

Abstract

A method for measuring and controlling dew point temperature of integrated air-conditioning includes obtaining dew point temperature measurement value corresponding to temperature and relative humidity measurement value of control object point as well as dew point temperature setting value corresponding to temperature and relative humidity setting value, comparing obtained dew point temperature measurement value with obtained setting value, using proportional integration and differential algorithm to control aperture of valve in separating range for making said measurement value be gradually tended to said setting value.

Description

The measurement of assembled air-conditioner dew point and control method

Technical field

The present invention relates to the measurement and the control method of air-conditioner dew point, particularly a kind of assembled air-conditioner dew point based on the calculating dew point that is specifically designed to constant temperature and humidity system is measured and control method.

Background technology

Along with advancing by leaps and bounds of contemporary science and technology, industrial constant-temperature constant-humidity air-conditioner has obtained using widely, and the high-acruracy survey control technology and the energy-conserving control technology of constant-temperature constant-humidity air-conditioner proposed requirements at the higher level.

Usually, the physical parameter that often relates in the artificial atmosphere comprises: dry-bulb temperature (T), relative humidity (RH), soft air pressure (P), dewpoint temperature (TW), water capacity (D), soft air enthalpy (H) etc.For the large-scale combined air-conditioning of band spray section, in order to realize constant temperature and humidity, the artificial atmosphere disposal route of deciding dewpoint temperature and then post bake that adopts cooling to dry to and set mostly in summer; In winter,, adopt new wind and the control of return air ratio enthalpy of mixing value, spray equal-enthalpy humidifying after preheating to reach dewpoint temperature control, and then utilize the artificial atmosphere disposal route of post bake (perhaps secondary return air) in order to consider energy efficient; Need not open in other season and to preheat, the enthalpy control, the spray equal-enthalpy humidifying that directly utilize new wind and return air ratio to mix reach the control dewpoint temperature, and then the artificial atmosphere disposal route of post bake (perhaps secondary return air).

At present, the control method of constant temperature and humidity assembled air-conditioner unit is in air-conditioning unit internal table cooler back an ordinary temp sensor to be set, with the temperature that measures as approximate dew point temperature measurements value (being the apparatus dew point measured value), and with this dew point temperature value of measuring with require wind pushing temperature and air-supply relative humidity have identical water capacity and the relative humidity under corresponding be about 95% temperature value setting value as dewpoint temperature, utilize intelligence instrument or Programmable Logic Controller (being called for short PLC), direct digital controller (DDC) (being called for short DDC) adopts the adjusting algorithm of proportional integral (being called for short PI) or proportional integral and differential (being called for short PID), by regulating the aperture of control air-conditioning unit surface cooler operation valve, the aperture of perhaps new return air proportioning valve, make current dew point temperature measurements value trend towards the setting value of dewpoint temperature, thereby reach the apparatus dew point temperature controlling, this also is a kind of key link of constant temperature and humidity system control.But in application of practical project, often do not reach 95% or surpass 97% through surface cooler cooled relative air humidity, and the inconsistent dew point temperature value of measurement that will cause of lower leaf is inaccurate on the air themperature behind the air-conditioning unit surface cooler.Therefore, air behind the surface cooler is according to the setting value requirement of having satisfied dewpoint temperature on the resulting dew point temperature value of the ordinary temp sensor measurement surface, but the measured value of actual air water capacity has produced deviation with the water capacity setting value, often cause the wind pushing temperature in subsequent control loops such as post bake or secondary return air or the deviation of air-supply relative humidity thus, thereby influence control accuracy, reduce reliability and wasted energy consumption.

The measurement of dewpoint temperature and electric weight change are sent nothing more than adopting two kinds of means, be that ordinary temp sensor measurement and professional dew point temperature sensor are measured, use for the ordinary temp sensor is obviously unreasonable, and the dew point temperature sensor of specialty not only costs an arm and a leg, serviceable life short (causing the damage of humidity sensor during near relative humidity easily in the apparatus dew point position measurement), and such sensor is not often considered the coupling influence of other factors such as soft air pressure and is adopted the electric weight of approximate treatment to become and send output, thereby measuring accuracy is low, and is difficult to popularize.

Present known a kind of measuring and control method of constant temperature and humidity system that be specifically designed to of also not finding based on the assembled air-conditioner dew point that calculates dew point.

Summary of the invention

Fundamental purpose of the present invention is to overcome deficiency of the prior art, and a kind of measuring and control method based on the assembled air-conditioner dew point that calculates dew point of constant temperature and humidity system that be used for is provided.

In order to solve the problems of the technologies described above, the present invention is achieved by the following technical solutions.

The invention provides a kind of measurement and control method of assembled air-conditioner dew point, may further comprise the steps:

(1) read the temperature that is arranged at controlled target point and the measured value of relative humidity sensor:

(2) obtain temperature and the pairing dew point temperature measurements value of relative humidity measurement value, temperature and the pairing dewpoint temperature setting value of relative humidity setting value of controlled target point according to following formula by controller:

Formula (one):

$\mathrm{Td}=\frac{b\×(\log \left(\mathrm{RH}\right)+\frac{a\×T}{b+T})}{a-(\log \left(\mathrm{RH}\right)+\frac{a\×T}{b+T})}$

Wherein:

T: dry-bulb temperature, unit ℃;

RH: relative humidity, the % of unit;

Td: calculate dewpoint temperature, unit ℃;

A, b are that constant is worked as T＞0 ℃, get a=7.45, b=235

When T＜0 ℃, get a=9.5, b=265

Formula (two):

$t_x=0.745-\frac{T+273.15}{647.3}$

$P_{\mathrm{SV}}=22120\·\mathrm{EXP}[(7.21275+3.981t_x+1.05t_x^3)\·(1-\frac{647.3}{T+273.15})]$

$D=\frac{6.2219\·\mathrm{RH}\·P_{\mathrm{SV}}}{(P-\frac{\mathrm{RH}}{100}\·P_{\mathrm{SV}})}$

$P_S=\frac{D\·P}{(D+622.19)}$

T _S＝6.98283+14.573·[Log(P _S)]+0.854004·[Log(P _S) ²]+0.0535149·[Log(P _S) ³]+0.00333·[Log(P _S) ⁴]+0.0003297·[Log(P _S) ⁵]

Wherein:

T: dry-bulb temperature, unit ℃;

RH: relative humidity, the % of unit;

P: soft air pressure, the kPa of unit

D: water capacity, the g/kg of unit

(3) dew point temperature measurements value and dewpoint temperature setting value are compared, passing ratio integration (PI) or proportional integral and differential PID regulate algorithm, surface cooler operation valve, humidifier operation valve or the new return air proportional control valve of branch process control air-conditioning unit be the aperture of at least a operation valve wherein, makes current dew point temperature measurements value trend towards the dewpoint temperature setting value.

As a kind of improvement of the present invention, controlled target point described in the step (1) is the main air delivery duct of air-conditioning unit outlet, and corresponding controlled target is the air-supply humiture.

As a kind of improvement of the present invention, controlled target point described in the step (1) is the return airway of air-conditioning unit outlet, and corresponding controlled target is the return air humiture.

As a kind of improvement of the present invention, controlled target point described in the step (1) is the room at air-conditioning unit outlet place, and corresponding controlled target is the room humiture.

Beneficial effect of the present invention is:

1, for the large-scale combined air-conditioning constant temperature and humidity control that contains the spray humidifier section

When needs utilized air supply parameter to realize constant temperature and humidity control, we only needed incorporate temperature/humidity sensor of configuration, and by measuring the dry-bulb temperature and the relative humidity of air, the method that just can calculate dew point solves all measurement parameters.Promptly utilize the temperature and the relative humidity of air-supply, calculate the dewpoint temperature of air-supply, need not ad hoc measure the machine dewpoint temperature and realize deciding dew point control.

Because the design feature of Air Conditioner has determined to exist serious thermal stratification phenomenon in air-conditioning, and the measurement of ordinary temp sensor is certain some temperature, can't reflect the accurate temperature of actual air-supply after mixing, even adopt the average temperatures sensor, also can only dwindle average error, utilize the temperature sensor measurement dewpoint temperature can't accurately obtain the actual value of temperature.

Adopt the obvious advantage of calculating dew point temperature measurements to be:

The method of A, calculating dewpoint temperature is that the wind pushing temperature that adopts air supply duct measured, the relative humidity of blowing are as input, this virtual measurement has obtained real air dew point temperature, and its reason is that its dewpoint temperature is invariable in the air secondary heating process.

B, in calculating the dew point scheme, because of the temperature and the relative humidity of blowing all feeds back in the loop of dewpoint temperature, therefore system has realized the coupling error of automatic elimination temperature and humidity, and can realize both real decoupling zero control, improved that traditional to utilize in the ordinary temp sensor measurement dewpoint temperature scheme wind pushing temperature, relative humidity that one parameter is arranged be the drawback of open loop control, thereby control is more precise and stable.

C, from the air-conditioning psychrometric chart, find out, system adopts the calculating dewpoint temperature can save a large amount of post bake amounts, because the relative humidity by apparatus dew point position, spray back can (not necessarily must reach the apparatus dew point about 95% less than 95%, as long as the dewpoint temperature of virtual measurement reaches the dewpoint temperature of automatic setting), then not only can reduce the spray flux of water pump, and the relative humidity of apparatus dew point position is more little, then air-conditioning post bake amount also can be more little, and energy-saving effect is obvious more.

2, for the lustration type assembled air-conditioner constant temperature and humidity control that contains the dry steam humidifier section

Although the dry steam humidification belongs to the isothermal humidification process, we can utilize the virtual dew point temperature measurement technology to divide process control surface cooling section, new return air ratio enthalpy mixer and the many corresponding by-pass valve controls of dry steam humidifier section equally, utilize post bake to control the temperature of air-supply or the relative humidity of independent control air-supply separately, this scheme dehumidifying priority principle more commonly used than engineering realizes that the precision of constant temperature and humidity control is higher, more stable, and reaches the maximum energy-saving pattern.

Description of drawings

Fig. 1 is the synoptic diagram that actual measurement dew point control method produces deviation.

Fig. 2 is that synoptic diagram is handled in the artificial atmosphere in the embodiment of the invention.

Embodiment

With reference to the accompanying drawings, will describe the present invention below:

The measurement of assembled air-conditioner dew point and control method may further comprise the steps:

(1) read the temperature that is arranged at controlled target point and the measured value of relative humidity sensor:

(2) obtain temperature and the pairing dew point temperature measurements value of relative humidity measurement value, temperature and the pairing dewpoint temperature setting value of relative humidity setting value of controlled target point according to following formula by controller:

Formula (one):

$\mathrm{Td}=\frac{b\×(\log \left(\mathrm{RH}\right)+\frac{a\×T}{b+T})}{a-(\log \left(\mathrm{RH}\right)+\frac{a\×T}{b+T})}$

Wherein:

T: dry-bulb temperature, unit ℃;

RH: relative humidity, the % of unit;

Td: calculate dewpoint temperature, unit ℃;

A, b are that constant is worked as T＞0 ℃, get a=7.45, b=235

When T＜0 ℃, get a=9.5, b=265

Formula (two):

$t_x=0.745-\frac{T+273.15}{647.3}$

$P_{\mathrm{SV}}=22120\·\mathrm{EXP}[(7.21275+3.981t_x+1.05t_x^3)\·(1-\frac{647.3}{T+273.15})]$

$D=\frac{6.2219\·\mathrm{RH}\·P_{\mathrm{SV}}}{(P-\frac{\mathrm{RH}}{100}\·P_{\mathrm{SV}})}$

$P_S=\frac{D\·P}{(D+622.19)}$

T _S＝6.98283+14.573·[Log(P _S)]+0.854004·[Log(P _S) ²]+0.0535149·[Log(P _S) ³]+0.00333·[Log(P _S) ⁴]+0.0003297·[Log(P _S) ⁵]

Wherein:

T: dry-bulb temperature, unit ℃;

RH: relative humidity, the % of unit;

P: soft air pressure, the kPa of unit

D: water capacity, the g/kg of unit

(3) dew point temperature measurements value and dewpoint temperature setting value are compared, passing ratio integration (PI) or proportional integral and differential (PID) are regulated algorithm, surface cooler by-pass valve control, humidifier by-pass valve control or the new return air ratio by-pass valve control of branch process control air-conditioning unit be the aperture of at least a operation valve wherein, thereby make current dew point temperature measurements value trend towards the dewpoint temperature setting value, reach the control of dewpoint temperature in the thermostatic constant wet control system.

If control air-supply humiture, then sensor is arranged on the main air delivery duct of air-conditioning unit outlet; If control return air humiture, then sensor is arranged on return airway; If control room humiture, then sensor is arranged in the room;

Obviously, the invention is not restricted to above embodiment, many distortion can also be arranged.All distortion that those of ordinary skill in the art can directly derive or associate from content disclosed by the invention all should be thought protection scope of the present invention.

Claims (4)

1. the measurement of an assembled air-conditioner dew point and control method may further comprise the steps:

(1) read the dry-bulb temperature that is arranged at controlled target point and the measured value of relative humidity sensor:

(2) obtain dry-bulb temperature and the pairing dew point temperature measurements value of relative humidity measurement value, dry-bulb temperature and the pairing dewpoint temperature setting value of relative humidity setting value of controlled target point according to following formula by controller:

Formula (one):

$\mathrm{Td}=\frac{b\×(\lg \left(\mathrm{RH}\right)+\frac{a\×T}{b+T})}{a-(\lg \left(\mathrm{RH}\right)+\frac{a\×T}{b+T})}$

Wherein:

T: dry-bulb temperature, unit ℃;

RH: relative humidity, the % of unit;

Td: calculate dewpoint temperature, unit ℃;

A, b are that constant is worked as T＞0 ℃, get a=7.45, b=235

When T＜0 ℃, get a=9.5, b=265

Formula (two):

$t_x=0.745-\frac{T+273.15}{647.3}$

$P_{\mathrm{SV}}=22120\·\mathrm{EXP}[(7.21275+3.981t_x+1.05t_x^3)\·(1-\frac{647.3}{T+273.15})]$

$D=\frac{6.2219\·\mathrm{RH}\·P_{\mathrm{SV}}}{(P-\frac{\mathrm{RH}}{100}\·P_{\mathrm{SV}})}$

$P_S=\frac{D\·P}{(D+622.19)}$

T _S＝6.98283+14.573·[Log(P _S)]+0.854004·[Log(P _S) ²]+0.0535149·[Log(P _S) ³]+0.00333·[Log(P _S) ⁴]+0.0003297·[Log(P _S) ⁵]

Wherein:

T: dry-bulb temperature, unit ℃;

RH: relative humidity, the % of unit;

P: soft air pressure, the kPa of unit

D: water capacity, the g/kg of unit

(3) dew point temperature measurements value and dewpoint temperature setting value are compared, passing ratio integral PI or proportional integral and differential PID regulate algorithm, surface cooler operation valve by seperating range control air-conditioning unit, humidifier operation valve or new return air proportional control valve be the aperture of at least a operation valve wherein, makes current dew point temperature measurements value trend towards the dewpoint temperature setting value.

2. the measurement of assembled air-conditioner dew point according to claim 1 and control method is characterized in that, controlled target point described in the step (1) is the main air delivery duct of air-conditioning unit outlet, and corresponding controlled target is the air-supply humiture.

3. the measurement of assembled air-conditioner dew point according to claim 1 and control method is characterized in that, controlled target point described in the step (1) is the return airway of air-conditioning unit outlet, and corresponding controlled target is the return air humiture.

4. the measurement of assembled air-conditioner dew point according to claim 1 and control method is characterized in that, controlled target point described in the step (1) is the room at air-conditioning unit outlet place, and corresponding controlled target is the room humiture.

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