Boots – shoes – and leggings
Patent
1986-03-24
1987-06-09
Lall, Parshotam S.
Boots, shoes, and leggings
73336, 364557, G01K 1700
Patent
active
046725601
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to an enthalpy calculator in which the enthalpy of a body of gas or humid air is calculated by an arithmetic unit in accordance with an enthalpy equation from the measured temperature and relative humidity of the body of gas, and in which the calculated value is converted into electrical signals which are output therefrom.
The enthalpy of humid air is obtained by the following equations (A) and (B) when the temperature and pressure thereof are within the ranges in which every-day air conditioning is carried out. obtained by an approximate expression that has hitherto been disclosed, such as the IFC Formulation for Industrial Use, must be substituted therein to obtain the saturated vapor pressure.
Accordingly, to obtain a value for the enthalpy of humid air using a conventional arithmetic unit it has been necessary to find the value of one other factor, in addition to the dry bulb temperature, as a measured value. That is to say, conventional methods depend on the humidity ratio, wet bulb temperature, relative humidity, and dew point temperature and, whichever method is used, the values measured are converted into enthalpy in accordance with equations (A) and (B) using an electronic computer. Any method depending on finding the dew point temperature or the humidity ratio has the drawbacks of the slow reaction speed and expensive sensing elements, and other methods depending on the wet bulb temperature, relative humidity, and dew point temperature have a disadvantage in that the solving of complicated equations are required.
SUMMARY OF THE INVENTION
According to this invention, the value of enthalpy is given by an arithmetic unit performing calculations using the following enthalpy calculation equations (C) and (D), which consist of a sum of the product of a linear function of the dry bulb temperature multiplied by a linear function of the relative humidity, and constants, the dry bulb temperature and the relative humidity being important elements in the air-conditioning of the environment, when a limitation is imposed on the range of temperature (about 20.degree.-30.degree. C.) of air in a room when healthy air conditioning is provided.
By using equations (C) and (D) according to this invention, a value of enthalpy which is more accurate than that read from a physchrometric diagram can be found easily without performing the conventional complicated calculations based on equations (A) and (B), provided that the temperature at which the enthalpy is calculated is within the temperature range used in practice.
The method of deriving equations (C) or (D) will now be described. FIG. 1 is a graph showing the values of enthalpy i calculated from a psychrometric diagram (i-x diagram) and the fundamental equations (A) and (B) for calculating enthalpy, with the condition that the dry bulb temperature is kept constant. In this case, the enthalpy can be approximated by a linear function of the relative humidity as expressed by equation (E) as follows: temperature are examined, they can be expressed by approximate expressions (F) and (G) which are linear functions of the temperature t within a certain range temperature of t.sub.1 to t.sub.2, as follows:
Therefore, by substituting equations (F) and (G) into equation (E), equations (C) and (D) can be obtained.
According to this invention, by measuring the dry bulb temperature and the relative humidity, it is possible, within a certain range of temperatures, to reduce the difference between the enthalpy value obtained by the simple calculation expressed by equation (C) or (D) and that obtained by the fundamental equations (A) and (B) to a minimum.
The following equation (H) provides values of the coefficients a, b, c, and d applied to the range of temperature from 20.degree. to 30.degree. C. using equation (C), based on temperatures set at 22.5.degree. and 27.5.degree. C. and relative humidities at 30 and 70%.
TABLE 1 ______________________________________
(kcal/kg')
i-i.sub.0
Relative Temperature (.degree.C.)
hum
REFERENCES:
patent: 3866026 (1975-02-01), de Vivy
patent: 3946308 (1976-03-01), Miura et al.
patent: 4078431 (1978-03-01), Mott
patent: 4182180 (1980-01-01), Mott
patent: 4380155 (1983-04-01), Paddock et al.
patent: 4574626 (1986-03-01), Kaya et al.
Katayama Akifumi
Mori Keijirou
Ueda Satoshi
Lall Parshotam S.
Matsushita Electric - Industrial Co., Ltd.
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