SAE J2234 pdf download
SAE J2234 pdf download.Equivalent Temperature.
1.The scope of this SAE Information Report is to:
a. Deline the Equivalent temperature.
b. Describe how it can be used to evaluate the performance of a heating and/or air-conditioning system in a vehicle.
c. Describe how it can be measured.
2. References
2.1 Applicable Publications—The following publications form a part of this specification to the extent specified herein.
2.1.1 ANSIIASHRAE P usucAr IoNs—Avail able from ANSI, 11 West 42nd Street, New York. NY 10036-8002.
ANSI/ASHRAE-1992—Thermal environmental conditions for human occupancy
ANSI/ASHRAE55-1992—Atlanta: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc.
2.1.2 ISO PuBucATioNs—Available from ANSI. 11 West 42nd Street. New York. NY 10036.8002.
1S07726—Thermal environments—Instruments and methods for measuring physical quantities, International Standards Organization, Geneva 1985
lSO7730—Moderate thermal environments—Determination of the PMV and PPD indices and specification of the conditions for thermal comfort, International Standards Organization, Geneva,1984
This equation, developed by Madsen (1984), agrees with the similar equations by Bedford (1936). Gagge (1940), and Mcintyre (1976).
The equivalent temperature may also be calculated from the PMV-equation [Fanger (1982), iSO 7730) by setting air temperature equal to mean radiant temperature and air velocity to 0 me’s.
It is seen that the equivalent temperature is influenced by the thermal Insulation of the clothing. A given air velocity (v8). has a higher cooling effect on nude skin (‘ — 0) than on skin covered with clothing (‘d > 0).
7. Measurement of Equivalent Temperature
7.1 IndIvidual Measurements—Air temperature, mean radiant temperature, and air velocity may be measured wIti individual sensors and the equivaleni temperature then calculated from Equation 5. The thermal insulation of the clothing must be evaluated before the calculation. (ASHRAE 55—92. ISO 7730)
The sensors must fulfill the requirements in ISO 7726.
7.2 IntegratIng Sensor—Measuring each parameter individually requires a lot of instrumentation and it is difficult to measure all parameters in the same position. Instead of measuring each parameter and then calculating the combined influence, it may be easier to use a transducer that integrates the three climate parameters into one temperature, the equivalent temperature.
The sensor requirements for direct measurements of equivalent temperature is that the size, color, and shape simulate the convective and radiant heat loss from a person shape and color of the human clothing/skin. The sensor must be heated to a surface temperature, which simulates the mean clothing surface temperature of a person. From the definition it is seen that the equivalent temperature depends on the clothing insulation, which means that the sensor should be able to simulate different clothing temperatures.
The mean clothinWskin surface temperature of a person for different combination of the thermal parameters may be calculated from the PMV-equation given in ISO 7730 (ISO 7730 (1984). Fanger (1982)).
These requirements are fulfilled with the sensor in Figure 1 The sensor has been carefully designed to simulate the dry heat loss from a person as precisely as possible. The size has been chosen so that the ratio between the heat loss by radiation and by convection is similar to that of a person.
When measuring the equivalent temperature, the sensor is heated, The surface temperature must therefore correspond to the mean doming surface temperature of the person that the sensor is simulating. The desired surface temperature Is maintained by means of a temperature-independent resistance wire wound around the senso body. The current through this wire is a measure of the heat loss from the sensor, At the same time, there is a wire evenly wound over the heated part of the sensor body. The resistance of this wire is a measure of the mean surface temperature of the body. By means of the measured heat loss and mean surface temperature, the equivalent temperature is estimated.
7.3 Thermal Manikin—In a vehicle the thermal conditions may give a nonuniform exposure on the body of a person. To simulate the human body in the best way, a thermal manikin may be used to measure the equivalent temperature. A thermal manikin [Wyon (1985), Madsen (1986j Is tilted with pliable joints so that it can be placed in different positions. Thermally it is divided into sections, each with its own heating system to ensure that each section will maintain exactly the surface temperature for the clothing it has been set for. After measuring the energy consumption of each of the sections. the equivalent temperature for each part of the body can be found.
Each segment of a thermal manikin operates as an equivalent temperature sensor (see 7.2), but with a shape that much better simulates the human body.
