Hello, I have several questions about air conditioning:
First Id like to recall tecnical background: ATR-72-500 has two packs, the left pack supplying air to flight deck and cabin and the right pack to cabin only. Packs discharge temperature is regulated by the automatic controller which adjust the temperature control valve adding hot air to cool air from the compresor/turbine section of the pack. My questions are:
1) What is the purpose of the hot by-pass valve and tic valve?
2) If I want to set cockpit temperature to lower level than cabin temperature, the left pack temp will be lower than the right pack temp, wont it? But there is an aspect that I dont understand: as the left pack also supplies air to cabin, than the cabin receives air of two different temp, cooler from the left pack and requested air temp from the right pack. In this case the cabin temp would be below requested level. Theorically, in this situation, right pack automatic temp controller should rise the right pack outlet temp to balance the impact of cooler air from the left pack. Is my intuition correct? It may be a silly question for you, guys but I cant find explicite answer in my systems manual and I try to understand deeply every aspect of a ATR-72 aircraft
3) Why the pack discharge temp is regulated by adding hot air to cooler air from the compresor/turbine section of the pack and why the discharge temp. isnt regulated only by compresor/turbin section of the pack? I know that on aircrafts like B744 adding trim air makes sense because the cabin has several section and for each section there can be set different temp, but on an ATR...?
Thanks guys for your response, sorry for my bad English.