Transient Thermal Comfort Modeling - Subways and ...

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Transient Thermal Comfort Modeling -. Subways and Stations. ASHRAE June 2008. • Yanzheng (Don) Guan Ph.D. P.E.. • Mohammad Tabarra Ph.D. CEng.
Transient Thermal Comfort Modeling Subways and Stations • Yanzheng (Don) Guan Ph.D. P.E. • Mohammad Tabarra Ph.D. CEng. • Davar Abi-Zadeh Ph.D. CEng.

• Hui Zhang Ph.D. • Edward Arens Ph.D. • Tiefeng Yu Ph.D. • Charlie Huizenga UC Berkeley ASHRAE June 2008

Significance • More than 160 cities have rapid transit systems. Twentyfive cities have new systems under construction. More cities are planning subway systems. --- World Metro List • 100 Millions of people are using subway daily • Subway environments affect comfort and well-being of passengers and operating personnel

Challenges • Highly transient and nonuniform environments • Passengers with different activity levels and various clothing insulations • Transitional space • Energy efficient and cost effective system • CFD cannot tell you thermal comfort… • Design tool to quantify and model thermal comfort

How Do Low Energy Strategies Affect Comfort? Spot cooling Directly conditioning occupied zone

Platform Screen Door (PSD) Separate the tunnel and the station

Disney Line Station, HK

Mong Kok Station, HK

How to Improve Comfort by New Architectural Designs?

Building-station Integration Large open space Large skylights “Green” Designs Opportunities: • Radiant cooling • Displacement ventilation • Innovative control strategies…

IFC Station, HK

St Pancras Station, UK

Thermal Index for Subway Application • Predicted Mean Vote (PMV) • Predicted Percent Dissatisfied (PPD) model • Warm Environment: Relative Warmth Index (RWI) • Cool Environment: Relative Strain Index (RSI) “Thermal comfort”, Fanger, 1972 “Subway Environmental Design Handbook”, DOT, 1976

ASHRAE Std 55: Acceptable comfort ranges of operative temperature (1.1 met, 0.1 m/s)

UCB Transient Thermal Comfort Model

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Physiology modeling

Psychological thermal perception modeling

Physiology Model

Upper Arm

Lower Arm

Solar load on the body

core muscle fat skin

Radiation model

core muscle fat skin

core muscle fat skin core muscle fat skin

core muscle fat skin

core muscle fat skin

16 body segments, 4 layers

Hand

Counter-current blood flow

Body-builder model

Psychological Model My leg is uncomfortable My leg is cold

Human subject testing

Overall, I’m warm Overall, I’m uncomfortable

Model prediction

Comfort Scale very comfortable

4

comfortable

2

just comfortable just uncomfortable

0 -0

uncomfortable

very uncomfortable

-2

-4

Threshold for thermal environment acceptability

Model Applications – Vehicle Comfort Solar radiation (W/m2)

Very comfortable

Very hot

Just comfortable Just uncomfortable

Very cold

Solar radiation coming through driver’s window reaches left arm, part of the right arm, hands, and left side of head

Very uncomfortable

These parts feel warmer…

…and experience local discomfort

Model Applications for Typical Building Non-uniform Environments

Cold window

Cooled ceiling

Displacement ventilation/UFAD

Heated floor

Solar radiation and façade comfort

UCB Comfort Model Validation – Vehicle Wind Tunnel Test • Wide range of realistic transient automobile thermal conditions • Measured skin and core temperatures, subjective votes and environmental conditions

Subway Thermal Comfort Graphic User Interface

Outdoor walking

Platform

Stalled train

A series of “phases” define •environmental conditions •passengers’ metabolic level and clothing •corresponding geometry surroundings

Scenario for a Typical Subway Riding 10 min outdoor

1 min mezzanine

5 min platform

1 min stairs

10 min in train

24s train coming, step into it

Comfort Simulation for Spot Cooling

just comfortable just uncomfortable Threshold for acceptability uncomfortable

very uncomfortable

Testing Radiant Cooled Panels

Cooled floor (20ºC/68ºF)

Cooled vertical panels (20ºC/ 68ºF)

Cooled ceiling panel (20ºC/ 68ºF)

Comfort Simulation for Radiant Panels

just comfortable just uncomfortable Threshold for acceptability uncomfortable

very uncomfortable

Comfort Simulation for PSD comfortable

just comfortable just uncomfortable Threshold for acceptability uncomfortable

very uncomfortable

Mitigation Measures of a Congested Train

Air temperature and humidity will increase

Ttunnel (ºC/ºF) Train ventilation

36(97), 31(88) 554 cfm

Activity Level and Core Temperature Increase

Suggestions in a Congested Train

• Ventilation of the train

• Quietly seated

• Taking off clothing

Thermal comfort and energy consumption 4

2 comfortable

0 -0 just comfortable Air Tempering

-2 uncomfortable No AC

-4 very uncomfortable

Thermal comfort

Relative energy consumption %

very comfortable 100 90 80 70 60 50 40 30 20 10 0

PSD

Spot cooling (85F)+ mezz vent

Spot cooling (82F)

Entire space 82F

Energy consumption

Radiant panel

No AC

New generation tools for future station design… • Complex thermal environments • Transient comfort model for design optimization Beijing South Station, China (Terry Farrell)

• Integrated design approach

Guangzhou New Station, China (FSDI)