JPH0210897B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an enthalpy output device that calculates and outputs enthalpy from the temperature and relative humidity of humid air. To find the enthalpy of humid air, the following formula is generally used within the range of temperature and pressure used in general air conditioning. i ₌ 0.240t + (597.3 + _0.441t ) Kg/Kg'] P is atmospheric pressure [mmHg], _hs is saturated vapor pressure [mmHg], is relative humidity [%], and i is enthalpy [kcal/Kg']. Therefore, conventionally, in order to determine the enthalpy of air, in addition to the dry bulb temperature, absolute humidity,
Alternatively, there was a method of determining wet bulb temperature, relative humidity, dew point temperature, etc. Although the method of determining dew point temperature or absolute humidity is relatively easy to calculate, it has drawbacks such as slow reaction speed of the detection element and expensive elements. The method of calculating has the disadvantage that the arithmetic expression becomes complicated. In order to be able to directly calculate enthalpy from dry-bulb temperature and relative humidity, which are important elements as environmental indices, the present invention has developed an exponential function that uses a linear function with dry-bulb temperature as a variable as a power, and relative humidity. This makes it possible to easily perform high-precision calculations using an arithmetic expression consisting of the sum of a product term and a linear function term with temperature as a variable. Next, an enthalpy output device which is an embodiment of the present invention will be explained with reference to FIGS. 1 to 3. FIG. 1 is a basic configuration diagram of this embodiment, in which 1 is a temperature signal section, a temperature signal generating section 2 is expressed by a linear function with temperature as a variable, and an index whose exponent is a linear function with temperature as a variable. It consists of a temperature signal converter 3 represented by . 4 is a multiplication section which multiplies the signals from the relative humidity signal section 5 and the temperature signal section 1. Reference numeral 6 denotes an addition section which combines the signal from the temperature signal section 7 expressed by a linear function with temperature as a variable and the multiplication section 4.
The enthalpy value is outputted to the output section 8 as an electric signal. In FIG. 2, A is a converter that converts temperature into an electrical signal, and the composite resistor 9 is composed of a temperature sensor 10 that detects temperature changes as a resistance. The potential of the terminal 11 is a value obtained by dividing the power supply voltage into the ratio of the combined resistor 9 and the resistor 12, and is a potential expressed as a linear function of temperature. B is a circuit that converts the voltage at the terminal 11 into a voltage expressed by an exponential function, and when the collector of the transistor 14 is connected to the inverting input terminal of the operational amplifier 13, the collector current is expressed by an exponential function of the base-emitter voltage. Therefore, the output terminal 15 of the operational amplifier outputs a voltage expressed by an exponential function with the input voltage as a power. The conversion section A and the circuit B constitute a temperature signal section 1. C is an operational amplifier 16 and a humidity sensor 1 that detects changes in relative humidity as changes in resistance.
A multiplication section configured by 7 outputs a voltage to a terminal 19 according to the amplification degree determined by the resistor 17 and the resistor 18 with respect to the input voltage of the terminal 15. That is, the voltage at the terminal 19 outputs a voltage value expressed by multiplying relative humidity by an exponential function whose exponent is a linear function with temperature as a variable. D is an adder that adds the output signal from the multiplier C and a voltage expressed by a linear function with temperature as a variable. Reference numeral 20 denotes a composite resistor including a temperature sensor 21 that detects temperature changes as resistance changes. The terminal 22 has a potential obtained by dividing the power supply voltage into the ratio of the resistor 20 and the resistor 23, and can be expressed as a linear function with temperature as a variable. The operational amplifier 24 is an adder for the voltage applied to the terminals 19 and 22, and outputs the enthalpy value as a voltage from the output terminal 25. The arithmetic unit of the enthalpy output device explained above is
When the enthalpy value is i, i=e ^at+c・+bt+d...(c) This is to execute the formula (c) expressed as follows. Here, a, b, c, and d are constants. This calculation formula (c) does not require the conventional complicated calculations of formulas (a) and (b) mentioned above, and within the practical temperature range where enthalpy calculations are performed, it is easier to read than using a hygrodynamic diagram. Highly accurate values can be obtained. Next, we will explain how to derive the arithmetic expression (c). In the hygrodynamic diagram (i-x diagram) and the basic formulas (a) and (b) for enthalpy calculation, it is difficult to express enthalpy as a simple relational formula between relative humidity and dry bulb temperature, but it is When it is held constant, enthalpy i can be approximated by a linear function of relative humidity as shown in FIG. 3, so it can be expressed by equation (2). i=m+n...(d) Here, m and n are constants. Next, if we create an approximate equation (d) for each temperature and consider the changes in coefficients m and n with respect to temperature, we get
The coefficient m can be approximated by an exponential function (E) of the temperature t, and the coefficient n can be approximated by a linear function (F) of the temperature t. m=e ^at+c ...(E) n=bt+c...(F) Here, a, b, c, and d are constants. Therefore, by substituting equations (e) and (f) into equation (d), equation (c) is obtained. The following equation (G) is for the temperature range 5℃ to 35℃.
This is an arithmetic expression calculated for the vicinity. i=e ^{(0.06333t-3.699)}・+0.2326t+0.1054...(G) To explain how to obtain equation (G), in basic equations (a) and (b), the relative humidity and enthalpy are calculated with the dry temperature constant. Find the relationship between i and approximate it using a linear equation using the enthalpy values at relative humidity of 30% and 70%. For example, when the dry temperature is 20°C, the relationship between enthalpy i and relative humidity is expressed by equation (H). i=0.08898+4.757...(H) Similarly, find the linear equation for the dry bulb temperatures of 10℃, 15℃, 25℃, and 30℃. Next, approximate expressions for each coefficient m and n are obtained by the least squares method, and m can be expressed as equation (Li) and n as equation (nu). m=e ^{0.06333t-3.699} ...(li) n=0.2326t+0.1054...(nu) Therefore, equation (g) can be found from equations (li) and (nu). Table 1 shows the accuracy comparison between the calculation formula (g) and the basic formulas (a) and (b).The enthalpy difference is 0.5 or less over the entire range, which is highly accurate, and within the range of practical temperature and relative humidity. The accuracy is sufficiently high. Equation (g) is from 5℃
This is an arithmetic expression that was calculated using the "predetermined temperature range" around 35°C. This temperature range is based on indoor air conditions (approximately 20°C
~30°C) and surrounding outdoor temperatures of approximately 30°C
The temperature range is ℃. Enthalpy values in this temperature range are necessary to realize energy-saving operation when determining air conditioning conditions, especially ventilation conditions. The above explanation has been made with reference to the range of 5° C. to 35° C. used for air conditioning control, but the temperature range used for drying, for example, is in a higher temperature range. Therefore, it is necessary to newly set constants a, b, c, and d in equation (c). The procedure in this case is the same as when formula (g) was derived.

[Table] As mentioned above, the enthalpy output device of the present invention is
It takes the dry bulb temperature and relative humidity, which are the most important environmental indices, as input and outputs the enthalpy value as an electrical signal.Once the dry bulb temperature and relative humidity are detected, other factors such as saturated vapor pressure can be calculated using approximate formulas or conversions. Since there is no need to search in a table or the like and direct calculations can be made, it is possible to easily calculate highly accurate values even when using an electronic computer. In addition, when performing air conditioning, the enthalpy value, which is the thermal energy held by the air, can be calculated directly from the target temperature and relative humidity, which has many advantages such as easy application to automatic control of air conditioning. It is what it is. In addition, although the calculation method of the present invention is composed of linear functions with temperature as a variable, even if higher-order functions higher than quadratic functions of the temperature variable are omitted, as described above, the practical accuracy is still low. It is enough. Furthermore, since it is constructed from a linear function of temperature, it can be constructed using a simple arithmetic circuit with a small number of constituent elements.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of an enthalpy output device according to an embodiment of the present invention, FIG. 2 is an electric circuit diagram thereof, and FIG. 3 is a diagram showing the relationship between relative humidity and enthalpy i. 1... Temperature signal section, 4... Multiplication section, 5... Relative humidity signal section, 6... Addition section, 10, 21... Temperature sensor, 17... Humidity sensor.

Claims (1)

[Claims] 1. A humidity sensor that converts relative humidity into an electrical signal, a temperature sensor that converts temperature into an electrical signal, and the signals of this temperature sensor and the humidity sensor as input, and the following formula i=e ^{at +c}・+bt+d a, b, c, d are constants t: dry bulb temperature: relative humidity However, a, b, c, d are i ₀ = 0.240t + (597.3 + 0.441t) x x = 0.622...h/ (P-h), then in the specified temperature range |i-i ₀ |≦
An enthalpy output device consisting of an arithmetic unit that performs an operation where the constant is selected to be 0.5, and where P is the atmospheric pressure of the equipment atmosphere, h is the saturated vapor pressure at the atmospheric pressure shown by P, and an arithmetic unit outputs i as an electrical signal. . 2. The arithmetic unit has an output of a relative humidity signal section that converts a relative humidity value into an electrical signal, and a temperature signal section that converts temperature into an electrical signal and is expressed by an exponential function whose exponent is a linear function with temperature as a variable. 2. The enthalpy output device according to claim 1, further comprising a multiplier for multiplying the output signal of the multiplier and a temperature signal expressed by a linear function with temperature as a variable. 3 The temperature signal section that performs multiplication with the relative humidity signal is
The voltage output section converts temperature changes into resistance changes and is expressed as an exponential function whose exponent is a linear function with temperature as a variable.The relative humidity signal section converts relative humidity into resistance changes and outputs signals based on relative humidity changes. The relative humidity signal output section changes the degree of amplification, and the temperature signal section that performs addition with the multiplication section output signal converts temperature changes into resistance changes and uses a voltage output section that converts temperature changes into resistance changes and is expressed as a linear function with temperature as a variable. The enthalpy output device according to claim 2, characterized in that: