Hello everyone,

I'm now working on programming a software to calculate Refrigeration Load for a Cold Room , we know that there are several types of load that need to be included in the calculation such as, solar transmission load, internal load and product load, but when it comes to Infiltration Air Load, there are several parameters that made me confuse, i refer to ASHRAE Handbook REFRIGERATION 1998 chap 12 (Refrigeration Load), in sub-chapter of Infiltration Air Load, Heat gain through doorays from air exchange is as follows:

qt = q(Dt)(Df)(1-E)

where
qt = average heat gain for the 24-h or other period,kW
q = Sensible and latent refrigeration load for fully established flow, kW
Dt = Doorway open-time factor
Df= Doorway flow factor
E = effectiveness of doorway protective device

my question is, how do we obtain the value of Dt, Df and E since it is not clearly stated in this book, is there any table that i have to refer to?? i appreciate any help from anyone of you, thnx