StatsDan
Computer
- Jan 29, 2009
- 1
Hi, I'm not a mechanical engineer, so I apologize for any ignorance.
I'm trying to estimate the heat gain through a wall over the course of a day. In my basic HVAC book, it says that the heat gain is equal to U * A * TETD where U is the U value, A is the area, and TETD is the total equivalent temperature difference. I have U and A no problem.
Rather than using the naive TETD values listed in ASHRAE tables, though, I'd like to compute a better estimate given that I have some additional information:
- the date, latitude, and longitude
- measurements of the total horizontal surface insolation reaching the ground (which accounts for sky clearness) at several times throughout the day
- the solar zenith angle, so with the insolation values, I can find the insolation upon each vertical surface
- the indoor and outdoor temperatures
- other weather conditions
- full wall construction properties
I'm looking for something that is still in parametric functional form (e.g., no differential equations). It would actually even be ok if there were an unknown parameter or two, so long as it was in a simple functional relationship.
I've been able to decompose all the angles involved with solar heat gain factors to do the equivalent for radiation heat gains through windows, but TETD has been giving me more trouble.
Thank you in advance.
Dan
I'm trying to estimate the heat gain through a wall over the course of a day. In my basic HVAC book, it says that the heat gain is equal to U * A * TETD where U is the U value, A is the area, and TETD is the total equivalent temperature difference. I have U and A no problem.
Rather than using the naive TETD values listed in ASHRAE tables, though, I'd like to compute a better estimate given that I have some additional information:
- the date, latitude, and longitude
- measurements of the total horizontal surface insolation reaching the ground (which accounts for sky clearness) at several times throughout the day
- the solar zenith angle, so with the insolation values, I can find the insolation upon each vertical surface
- the indoor and outdoor temperatures
- other weather conditions
- full wall construction properties
I'm looking for something that is still in parametric functional form (e.g., no differential equations). It would actually even be ok if there were an unknown parameter or two, so long as it was in a simple functional relationship.
I've been able to decompose all the angles involved with solar heat gain factors to do the equivalent for radiation heat gains through windows, but TETD has been giving me more trouble.
Thank you in advance.
Dan
