JPS61191952A - Absolute humidity output apparatus - Google Patents

Abstract

PURPOSE:To elevate the computing speed while simplifying the circuitry of an arithmetic unit, by computing an absolute humidity from a dry bulb temperature and relative humidity by a specified simple formula. CONSTITUTION:A moisture signal voltage output section 1 outputs a voltage represented by a linear function with the relative humidity phi from a humidity signal output section 5 as variable and a temperature signal voltage output section 2 changes the amplication factor based on a resistance represented by a linear function with the dry bulb temperature (t) from a temperature signal output section 6 as variable. A multiplier 3 multiplies a temperature output signal and a relative humidity output signal to output an absolute humidity (x) to an output section 4 as voltage value. Then, the absolute humidity (x) determined by an arithmetic unit A composed of output sections 1, 2 and 4 and multiplier 3 is obtained by computing the function x=atphi+bt+cphi+d expressed by constants (a), (b), (c) and (d), the relative humidity phi and the dry bulb temperature (t). Here, constants a-d can be obtained based on a moist air diagram and a basic formula for computing the absolute humidity.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an absolute humidity output device that calculates absolute humidity from the temperature of humid air and relative humidity and outputs it as a signal in the field of air conditioning measurement and control. .

Conventional technology Conventionally, when calculating the absolute humidity of humid air, within the range of dry bulb temperature and pressure used in general air conditioning, it is calculated from the following formulas (a), (b), and (c). There is.

X=O0622・ψ・h(of/(P−ψh(of
−・・・・・・・・・・(a) Here, t is the dry bulb temperature CC], ψ is the relative humidity [chi], and X is the absolute humidity [kg/
/9'], Tc is the critical temperature, θ is the ratio (-) of the absolute temperature to the critical temperature, P is the atmospheric pressure (1rJH9), PC is the critical pressure, and kl and 9 are constants. That is, as a calculation formula for the saturated vapor pressure, the absolute humidity X was obtained by substituting equation (c) of the practical international equation of state into equation (a).

Problems to be Solved by the Invention However, in the conventional method, in order to calculate the absolute humidity international state equation h
Since the absolute humidity X was calculated using the formula (c) of
It took a lot of effort to calculate.

The present invention has been made in view of the above points, and the dry bulb temperature
Therefore, without performing the conventional complicated calculations using formulas (a), (b), and (c), the absolute The object of the present invention is to provide a humidity output device.

Means for Solving the Problem In order to solve this problem, the present invention provides a humidity signal output section that converts the relative humidity ψ into a signal, a temperature signal output section that converts the dry bulb temperature t into a signal, and a temperature signal output section that converts the dry bulb temperature t into a signal. A function x=atψ+bt with a temperature signal and a humidity signal as input, and absolute humidity X expressed by constants c, b, c, d, relative humidity ψ, and dry bulb temperature t.
The configuration includes an arithmetic unit that performs an arithmetic operation based on +cψ+d and outputs a signal.

Effect With the above configuration, dry bulb temperature t, relative humidity ψ, and constants c, b, c,
The absolute humidity I can be easily calculated by adding and multiplying d.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 8.

Figure 6 shows the absolute humidity when the relative humidity ψ is constant, based on the hygrodynamic diagram (i-X diagram) and the basic formulas (a), (b), and (c) for calculating absolute humidity. The value of humidity X is plotted against the dry bulb temperature t. In this case, the absolute humidity I cannot be approximated by a linear function of the dry bulb temperature, but can be expressed by the following equation.

x = mψ+n ・・・・・・・・・・・・）
Here, m and n are constants.

Next, considering the correction of coefficients m and n for each temperature, we get
In a certain temperature range t1 to t2, as shown in FIGS. 7 and 8, both m and n can be expressed by approximations (E) and (E) of linear functions of temperature t.

m=at+c...◆・A...(E) n=
bt+d ・・・・・・・・・・・・(to) Here, c, b, c, and d are constants.

Therefore, by substituting the expressions (e) and (e) into the expression (i), we get
(g) Equation is obtained.

x = a t ψ + bt + c ψ + d
・・・・・・・・・・・・(G) Also, the equation of the straight line at t = 20'C and the equation of the straight line at t = 30°C in Figure 6 are respectively! =1.44653X109)-9,62541X1
0-5t=20°C x=2.68621X10 ψ-3.25094X1
0-'t = 3σC, and Figures 7 and 8 are graphs obtained by calculating this in the range of t = 20 to 30'C, so m,
n is m=1.23968X10 't-1.06181X1, respectively
0-'n=-2,2884X10"-5t+3°721
It becomes 19X10-'.

Therefore, the constant of a%d is a=1゜23968X10-5 b=-2,2884X10-5 c=-1,06181xlo-' cl-3.72119X10' becomes.

Here, the absolute humidity X obtained by substituting the above constants a% d into equation (g) and the absolute humidity temperature t20
~30'C1 The results of comparison over the entire range of relative humidity ψ20 to 100% are shown in the table.

1o'x (kg/lca') From the above table, the difference between absolute humidity X and Io is 5400X10-
It can be seen that the accuracy is sufficiently high within the range of practical temperature and relative humidity as it is less than 'kg/icg'.

Also, change the relative humidity range and use the calculation formula (e)), (f)
By determining each coefficient of , it is possible to easily change the temperature range subject to calculation.

Also, equation (g) is x=a(t+p)(ψ+q)+r −−−−−−−
-=(a) However, p==c/c, q=b/c, r=d-
It can be expressed as apq. By transforming this equation, we can create a circuit with a circuit that outputs the linear functions of t and ψ, a circuit that multiplies their outputs, and a circuit that adds a constant to the multiplied output. The circuit configuration is simplified.

An embodiment of an absolute humidity output device that performs the calculation expressed by equation (7) will be described with reference to FIGS. 1 to 5.

FIG. 1 is a basic configuration diagram of an embodiment of the present invention. Reference numeral 1 denotes a humidity signal voltage output section which outputs a voltage expressed by a linear function with the relative humidity ψ from the humidity signal output section 6 as a variable.
2 is a temperature signal voltage output section which changes the degree of amplification by a resistance expressed by a linear function with the dry bulb temperature t from the temperature signal output section 6 as a variable, and 3 is a multiplier that changes the amplification degree relative to the temperature output signal. The absolute humidity X is multiplied by the humidity output signal and outputted to the output section 4 as a voltage value. And humidity voltage output section 1. The temperature signal voltage output section 21, the multiplier 3, and the output section 4 constitute an arithmetic unit A.

A more specific example will be explained with reference to FIG.

In the figure, 7 is a humidity sensor consisting of a resistor 8 that detects humidity changes as resistance changes, and the voltage value at terminal 9 is the value obtained by dividing the voltage applied to terminal 10 by the ratio of humidity sensor 7 and resistor 11. A linear function of the relative humidity ψ is constructed, and a humidity signal voltage is output. 12 is an operational amplifier, and when a voltage expressed as a linear function of relative humidity ψ is input to an inverting input terminal, a voltage is outputted to a terminal 16 according to an amplification degree determined by a combined resistance 16 of a resistor 13 and a thermistor 14. Here the thermistor 14
is a temperature sensor, which uses a thermistor with a large B constant and outputs a temperature signal voltage expressed by a linear function with temperature t as a variable. The output voltage at terminal 16 is relative humidity ψ
The product of the linear function with temperature as a variable and the linear function with temperature as a variable is output. The output section 4 is a constant addition section using an example of an approximate calculation formula, and adds the voltage at the terminal 16 and the voltage at the terminal 18 using the operational amplifier 17 as an adder.

As a result, the absolute humidity X expressed by the approximate calculation formula (g) is outputted to the terminal 19 as a voltage value.

FIG. 2 shows a second embodiment of the present invention, and part B in the figure is a relative humidity signal voltage output part, and an operational amplifier 10.
When a capacitor 107 is connected to the non-inverting input side of the operational amplifier 6, and a resistor 108 is connected in the negative feedback circuit, the capacitor 107 and the resistor 108 are connected from the output terminal 109 of the operational amplifier 106.
A square wave with a constant frequency that is inversely proportional to the capacitance of 8 is generated.

A collector current of a constant value flows through the transistor 110 only when the potential of the terminal 109 is high, charging a capacitor 111 that detects a change in relative humidity as a change in capacitance, and charging and smoothing a capacitor 112. On the other hand, the potential of the capacitor 112 is expressed by a linear function with relative humidity ψ as a variable.

The 0 part is a temperature signal voltage output part, the composite resistor 115 is a composite resistor consisting of a resistor 116 that detects temperature change as a resistance change, and the potential of the terminal 117 is the power supply voltage output part.
6 and the resistance 118. That is, the potential of the terminal 117 can be approximately expressed as a linear function of the resistance 116, that is, the temperature variable.

The D section is a multiplication section, which includes a FET 119 and an operational amplifier 120.
It multiplies the input voltages at terminals 114 and 117, amplifies it to a voltage according to the amplification degree determined by resistor 121 and FET 119, and outputs it from terminal 122.

The E section is an adder section that connects the voltage at the terminal 122 and the power supply voltage to the resistor 12.
FIG. 4 shows a third embodiment of the present invention. In the figure, reference numeral 206 is a composite resistor consisting of a resistor 267 that detects temperature change as a resistance change. The voltage value at terminal 208 is a value obtained by dividing the voltage between terminals 209 and 210 into the ratio of the resistance values of resistor 206 and resistor 211, and can be expressed as a linear function with resistance 207, that is, temperature, as a variable. The operational amplifier 212 is a common-mode amplifier, and when a voltage expressed as a linear function of temperature is input to a non-inverting input terminal, a voltage corresponding to the amplification determined by a resistor 213 and a composite resistor 215 consisting of a resistor 214 that detects a change in relative humidity as a resistance change is generated. is output to terminal 216. If the value of the combined resistance 216 is the resistance value of the resistance 214, that is, the resistance value expressed by a linear function of relative humidity, then the voltage at the terminal 216 will be a voltage value expressed by the product of a linear function of temperature and a linear function of relative humidity. . The operational amplifier 217 is an in-phase adder that adds the voltage value at the terminal 216 and the voltage value at the terminal 220, which indicates the potential obtained by dividing the voltage between the terminals 209 and 210 into the ratio of the resistance values of the resistor 218 and the resistor 21°9. and outputs a voltage to the terminal 221. That is, the voltage value of the terminal 221 is the voltage value of the absolute humidity value expressed by the sum of the product term of the linear function of temperature and the linear function of relative humidity and a constant. 30 in the figure shows an example.
6 is a resistor 307 that detects a change in relative humidity as a change in resistance.
It is a composite resistance consisting of The voltage value of terminal 308 is terminal 3
The value obtained by dividing the voltage between 09 and 310 into the ratio of the resistance values of the resistor 306 and the resistor 311 can be expressed as the resistance 3o7, that is, as a linear function with relative humidity as a variable. The operational amplifier 312 is a common-mode amplifier, and when a voltage expressed as a linear function of relative humidity is input to the non-inverting input terminal,
Resistance 313. Resistor 3 that detects temperature changes as resistance changes
14 combined resistance 315 and constant voltage output section 316
A voltage corresponding to the amplification degree determined by is output to the terminal 317.

Here, it is possible to set the value of the combined resistance 315 to the resistance 314, that is, a resistance value that can be expressed as a linear function of temperature.
Since it is not easy to make the constant term match the value of equation (a), the constant term can be easily made to match by inserting a constant voltage output section in series with the resistor. Therefore, the voltage value at the terminal 317 is a voltage expressed by the product of a linear function of temperature and a linear function of relative humidity. operational amplifier 31
8 is an in-phase adder, which inputs the voltage value of terminal 317 and the voltage value of terminal 30.
The voltage value at terminal 321, which indicates the potential obtained by dividing the voltage between 9 and 31o into the ratio of the resistance values of resistor 319 and resistor 320, is added, and the voltage value at terminal 322 is a linear function of temperature and relative humidity. This is the voltage value of the absolute humidity value expressed as the sum of the product term and the constant term.

More than the effects of the invention, as is clear from the examples, the absolute humidity output device of the present invention can calculate the relative humidity I using the simple formula x = atψ + bt + cψ + d, so the circuit configuration of the arithmetic unit used for this calculation is It can be simplified and the calculation speed can be improved. Furthermore, by changing the constants in the circuit, it is possible to move the temperature and humidity range for calculation, making it possible to use it over a wide range of areas. Furthermore, since the measurements and items required for the calculation are the dry bulb temperature t and the relative humidity ψ, which are the most important environmental indexes, it can be directly applied to air conditioning control, and its effects are significant.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an absolute humidity output device according to an embodiment of the present invention, FIG. 2 is an electric circuit diagram of the same, and FIGS. 3, 4, and 5 are respectively other embodiments of the present invention. The electrical circuit diagram of the absolute humidity output device in the example, FIG. 6 is a diagram showing the relationship between relative humidity I and absolute humidity ψ, FIG. 7 is a diagram showing the relationship between dry bulb temperature t and coefficient m, and FIG. 8 is a diagram showing the relationship between relative humidity I and absolute humidity ψ. It is a figure showing the relationship between dry bulb temperature t and coefficient n. 1... Humidity signal voltage output section, 2... Temperature signal voltage output section, 3... Multiplier, 4...
... Output section, 6... Humidity signal output section, 6...
...Temperature signal output section. Name of agent: Patent attorney Toshio Nakao and one other name
2 Fig. 4 (! I Fig. 5! s6 Fig. Aψ

Claims (5)

[Claims] (1) a humidity signal output section that converts relative humidity ψ into a signal;
A temperature signal output section that converts the soft bulb temperature into a signal, the humidity signal and the temperature signal are input, and the absolute humidity x is calculated by constants a, b,
A signal is calculated based on a function expressed by c, d, relative humidity ψ, and soft bulb temperature t, that is, x=atψ+bt+cψ+d, and the absolute humidity x is calculated within a predetermined range of absolute humidity ψ and dry bulb temperature t. However, the ratio between the soft ball temperature t and the critical temperature T_C is θ=(t+273.15)/T
Practical international equation of state h(
Absolute humidity x_ based on the practical international equation of state expressed as θ)
0, that is, x_0=(0.622ψh(θ))/(P
-ψh(θ)) and an absolute humidity output device comprising a computing unit that determines the constants a, b, c, and d so that the error does not become large. (2) Absolute humidity x_0 and x=a based on the practical international equation of state
Claim 1 in which the constants a, b, c, and d are determined so that the error from the absolute humidity x determined from tψ+bt+cψ+d is (|x−x_0|)/(x_0)×100<5.
Absolute humidity output device as described in section. (3) The absolute humidity output device according to claim 1, wherein the signal is an electric signal. (4) The computing unit calculates the absolute humidity x by q=b/a, p=c/a,
Function x=a(t+p
)(ψ+q)+r. The absolute humidity output device according to claim 1. (5) The arithmetic unit converts relative humidity changes into voltage changes, and has a relative humidity signal voltage output section that is expressed as a linear function with relative humidity as a variable, and a relative humidity signal voltage output section that converts temperature changes into resistance changes and is expressed as a linear function that uses temperature as a variable. Claim 1 comprising a temperature signal voltage output section that changes the degree of amplification by a resistance expressed by a function, and comprising a multiplier for the temperature output signal and the relative humidity output signal.
Absolute humidity output device as described in section.