Optimization of the thermal comfort index PMV-PPD in train saloons

ABSTRACT

The thermal comfort in terms of stuffiness in high-speed train saloons in summer is studied with respect to the ISO 7730 standard. The critical factors that affect thermal comfort in trains are determined by Causal analysis. Using the Taguchi experimental method, an optimization design for the Predicted Mean Vote (PMV) and the Predicted Percentage Dissatisfied (PPD) for experimental cars is determined. The difference between the original thermal comfort index and that for the optimal parameter settings for two saloons are compared. The results show that the respective optimized thermal comfort indices for the two saloons are (−0.07, 5.11%) and (−0.01, 5.00%), which values are similar to the ideal standard for ISO 7730. Compared with the original design, the PMV in a business car increases by 76.7% and the PPD increases by 25.6%. The PMV in Car10 increases by 95.8% and the PPD increases by 18.7%. The optimized parameter settings ensure a better and more stable interior temperature and relative humidity.

KEYWORDS:

• Thermal comfort
• ISO 7730 standard
• taguchi method
• PMV and PPD index

Disclosure statement

No potential conflict of interest was reported by the author(s).

Nomenclature

$CF$ Correction factor

$CR$ Contribution ratio

$DO{F}_n$ Number of degrees of freedom for a control factor

$F$ Variance in averages between several groups

$f_{cl}$ Clothing area parameter

$h_c$ Convection heat transfer coefficient

$I_{cl}$ Thermal insulation of clothing

$L_i$ Number of levels of n

m Mean value

M Metabolism rate

$MSD$ Mean square deviation

N Number of experiments

n Number of samples

$P_a$ Water vapor pressure

S Standard deviation

$S{S}_{error}$ Sum of square error

$S{S}_{factor}$ Squares for a factor

$S{S}_{total}$ Total Sum of Squares

$S{S}_n$ Sum of the squares for a factor

$S{S}_n^{\prime }$ Net sum of the squares for a factor

$S{S}_A$ Sum of squares for the factor A

$sum{A}_n$ Sum of the observed values for level n

$T_a$ Temperature

$T_{mrt}$ Mean radiant temperature

$t_{cl}$ surface temperature of clothing

$V_a$ Relative wind velocity

$V_{ar}$ Variance

$V_i$ Value of the variance for the sum of the squares

$V_{error}$ Value of the variance for the error

$V_{epooled}$ Value of the variance for the total error

W External work

$y_i$ Measured data

$\bar{y}$ Average of the measured data

$\varphi$ Air humidity