I would be happy if someone helps me with the following issue.
I use system 6 for my baseline simulation in weather 1b which is hot climate . The AHU consists of Outdoor air mixer, variable fan, electric heating coil and DX cooling coil. I ran the simulation and the flow rates are fine (the OA and maximum flow rate). However, I have problem with the DX coil. I think the coil can not cool down air temperature enough to satisfy my set point temperature that is 14C. The profile before and after cooling coil has about 14-15C temperature difference with a special pattern. The temperature should be constant (14C) but it cools down and keeps it pattern like before the cooling coil. I just noticed that when I turn off the out door air (OA), the temperature becomes
constant (14C) and it's fine. However when I add the outdoor air flow rate (about 46C in July) again, the cooling coil cools down but as I mentioned, again it does not cool down to 14C. Could anyone please let me know what else I can check for solving this problem? Can the cooling curves cause the problem?
Thanks,
Eshagh