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Addres your questions related to Project 1 Define parameters for Thermal Comfort and

Lecture Objectives. Addres your questions related to Project 1 Define parameters for Thermal Comfort and Air Quality analyses in CFD. Thermal comfort. Temperature Relative humidity Air velocity Mean radiant temperature. Thermal comfort. Temperature and relative humidity.

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Addres your questions related to Project 1 Define parameters for Thermal Comfort and

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  1. Lecture Objectives Addres your questions related to Project 1 Define parameters for • Thermal Comfort and • Air Quality analyses in CFD

  2. Thermal comfort • Temperature • Relative humidity • Air velocity • Mean radiant temperature

  3. Thermal comfort Temperature and relative humidity

  4. Thermal comfort Velocity Can create draft Draft is related to air temperature, air velocity, and turbulence intensity.

  5. Thermal comfort Mean radiant temperature potential problems Asymmetry Warm ceiling (----) Cool wall (---) Cool ceiling (--) Warm wall (-)

  6. Prediction of thermal comfort • Predicted Mean Vote (PMV) • + 3 hot • + 2 warm • + 1 slightly warm • PMV = 0 neutral • -1 slightly cool • -2 cool • -3 cold • PMV = [0.303 exp ( -0.036 M ) + 0.028 ] L • L - Thermal load on the body • L = Internal heat production – heat loss to the actual environment • L = M - W - [( Csk + Rsk + Esk ) + ( Cres + Eres )] • Predicted Percentage Dissatisfied (PPD) • PPD = 100 - 95 exp [ - (0.03353 PMV4 + 0.2179 PMV2)] Empirical correlations Ole Fanger

  7. IAQ parameters Number of ACH quantitative indicator ACH - for total air - for fresh air Ventilation effectiveness qualitative indicator takes into account air distribution in the space Exposure qualitative indicator takes into account air distribution and source position and intensity

  8. IAQ parameters • Age-of-air air-change effectiveness (EV) • Specific Contaminant Concentration contaminant removal effectiveness e

  9. Single valueIAQ indicatorsEv and ε • Contaminant removal effectiveness (e) • concentration at exhaust • average contaminant concentration Contamination level • 2. Air-change efficiency (Ev) • shortest time for replacing the air • average of local values of age of air Air freshness

  10. Depends only on airflow pattern in a room We need to calculate age of air (t) Average time of exchange What is the age of air at the exhaust? Type of flow Perfect mixing Piston (unidirectional) flow Flow with stagnation and short-circuiting flow Air-change efficiency (Ev)

  11. Air exchange efficiency for characteristic room ventilation flow types

  12. Contaminant removal effectiveness (e) • Depends on: • position of a contaminant source • Airflow in the room • Questions 1) Is the concentration of pollutant in the room with stratified flow larger or smaller that the concentration with perfect mixing? 2) How to find the concentration at exhaust of the room?

  13. Ev= 0.41 e= 0.19 e= 2.20 Differences and similarities of Evande Depending on the source position: - similar or - completely different air quality

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