[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [EnergyPlus_Support] Enthalpy conversion from US --> SI

The conversion is not a straight multiplication because the zero of the 
IP enthalpy scale is dry air at 0 degrees Fahrenheit whereas the zero of 
the SI enthalpy scale is dry air at 0 degrees Celsius.

Using the values of the coefficients in Function PsyHFnTdbW in 
Energyplus and the corresponding IP values obtained using the conversion 
factors in Chapter 37 of the ASHRAE Handbook of Fundamentals:

Hip =  0.2398*((1.8*Hsi/1.00484E3)+32)    Btu/lb

Hsi =1.00484E3*(((Hip/0.2398) -32)/1.8)    J/kg



On 5/28/2008 1:31 PM, JV Dirkes II wrote:
>
> Dear E+ Forum,
>
> Will someone please confirm the following? (I'm not familiar with
> enthalpy values in SI measure and want to be sure I am converting
> values properly) Thanks!
>
> Enthalpy (US) = BTU/lb
> Enthalpy (SI / E+) = J/kg
>
> "X" BTU/lb * 1055 J/BTU * 2.2 lb/kg = "X" * 2321 J/kg
>
> e.g., 28 BTU/lb = 64,988 J/kg
>
>  

-- 
__________________________________
Philip Haves
Leader, Commercial Building Systems Group
Lawrence Berkeley National Laboratory
One Cyclotron Road, MS 90R3111
Berkeley, CA 94720-8134
(510) 486 6512 (office)
(510) 486 4089 (fax)

------------------------------------

The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/join
    (Yahoo! ID required)

<*> To change settings via email:
    mailto:EnergyPlus_Support-digest@xxxxxxxxxxxxxxx 
    mailto:EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/