Psychrometrics - -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 dry bulb temperature - f 10 20 30 40 50 60 70 80 90 100 110

Download Psychrometrics -   -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 dry bulb temperature - f 10 20 30 40 50 60 70 80 90 100 110

Post on 23-Apr-2018

214 views

Category:

Documents

2 download

Embed Size (px)

TRANSCRIPT

  • ARCH 373: ENVIRONMENTAL SYSTEMS 2

    Ball State University | Department of Architecture | Summer 2014 | Grondzik

    LABORATORY ONE

    Psychrometrics

    WEEK 1

    15 MAY

    The objective of this lab exercise is to provide hands-on experience using the psychrometric chart. The psychrometric chart is a key fi xture in the design of active climate control (HVAC) systems, as it provides a roadmap for the properties of moist air and the energy implications of changing those properties. The psychrometric chart is also very useful for condensation and evaporative cooling feasibility analyses (activities directly related to passive systems).

    1. Assume that two of the various properties of the air in a room have been measured using low cost portable instrumentation (such as demonstrated in class): (a) the dry bulb air temperature = _____ deg F (b) the relative humidity = _____ %

    Determine the:

    (c) absolute humidity = ________________ (units = _______________________)

    (d) wet bulb temperature = _____________ (units = _______________________)

    (e) enthalpy = _______________________ (units = _______________________)

    (f) specifi c volume = _________________ (units = _______________________) (g) dew point temperature = ___________ (units = _______________________)

    2. Describe one or more ways in which winter condensation potential on windows in contact with air at these conditions might be reduced via psychrometric manipulation (changing the properties of the air and/or the temperature of materials).

    3. How much sensible energy will be required to heat a pound of outdoor air from the Ft. Wayne winter design condition (Table B.1 MEEB) of 2 deg F to the indoor condition described in part 1?

    4. How much sensible and how much latent energy will be required to cool a pound of outdoor air from Evansville summer design conditions (Table B.1 MEEB) of 90 deg F dry bulb; 75 deg F wet bulb to the indoor conditions described in part 1?

    The following equation defi nes sensible energy requirements versus airfl ow rate: Btuh = (cfm) (1.1) (delta t)The following equation defi nes latent energy requirements versus airfl ow rate: Btuh = (cfm) (4840) (delta W)

  • -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130

    DRY BULB TEMPERATURE - F

    10

    20

    30

    40

    50

    60

    70

    80

    90

    100

    110

    120

    130

    140

    150

    160

    170

    180

    190

    200

    210

    10 15 20 25 30

    35

    40

    45

    50

    55

    55

    60

    60

    65

    70

    EN

    TH

    AL

    PY

    - B

    TU

    PE

    R P

    OU

    ND

    OF

    DR

    Y A

    IR

    0

    5

    10

    15

    20

    25

    30

    35

    40

    45

    50

    EN

    TH

    ALP

    Y - B

    TU

    PE

    R P

    OU

    ND

    OF D

    RY

    AIR

    SA

    TU

    RA

    TIO

    N T

    EM

    PE

    RA

    TU

    RE

    -

    F

    -50

    05

    510

    1015

    1520

    2025

    2530

    3035

    3540

    4045

    45 50

    50 55

    55 60

    6065

    65

    70

    70

    75

    75

    80

    80

    85 WET BULB TEM

    PERATURE - F

    85

    90

    15%

    25%

    2 %

    4 %

    6 %

    8 %

    1 0 % R EL A T I V E

    H U M I DI T Y

    2 0 %

    3 0%

    4 0%

    5 0%

    60%

    70%

    80%

    90%

    12.0

    12.5

    13.0

    13.5

    14.0

    SP

    EC

    IFIC

    VO

    LU

    ME

    ft/lb O

    F D

    RY

    AIR

    14.5

    15.0

    15.5

    HU

    MID

    ITY

    RA

    TIO

    - G

    RA

    INS

    OF

    MO

    IST

    UR

    E P

    ER

    PO

    UN

    D O

    F D

    RY

    AIR

    PSYCHROMETRIC CHARTBAROMETRIC PRESSURE 29.921 inches of Mercury

    Linric Company Psychrometric Chart, www.linric.com

    .1

    .2

    .3

    .4

    .5

    .6

    .7

    .8

    .9

    1

    1.1

    1.2

    1.3

    VA

    PO

    R P

    RE

    SS

    UR

    E -

    IN

    CH

    ES

    OF

    ME

    RC

    UR

    Y

    -20

    0

    10

    20

    25

    30

    35

    40

    45

    50

    55

    60

    65

    70

    75

    80

    85

    DE

    W P

    OIN

    T -

    F

    lab1psychchart-ip

Recommended

View more >