I am new and have a math and finance background. Because of my work I am starting to get into engineering related questions, specifically in piping. I flyfish a lot and can give pointers to anyone that helps me with my questions. Say I have a 5-10' length of pvc, metal or copper pipe that is 4 or 5" diameter with x number of feet in pvc pipe attached to it. The 5-10' length is surrounded by 67°F water and the air traveling through the pipe is 70-100°F The air traveling through the pipe is exchanged at a rate of 45 cfm. The air is filtered, so there might be turbulence and I will have to calculated with and without turbulence. My question is how to calculate what 45 cfm flowing through a 4-5" diameter pipe 5-10' length will cool to? 90°F air going in and x temp coming out of the 5-10' section that is surrounded by 67°F water. Any help is appreciated.