You are designing a floor heat system that uses a glycol/water mixture for a new DOT building in Williston, ND. The glycol/water mixture comes out of a boiler system at a total flow rate of 50 gpm (gallons/min). The glycol/water mixture then enters 5/8 inch Pex (smooth plastic pipe with a wall thickness of 0.0625") floor heat pipe. The system has a total length of 18,000 ft for floor heating pipe before returning to the boiler system. The glycol/water mixture has a viscosity of 0.75 CP and a specific gravity of 1.02. The entire system has 50 return bends and 2 couplings (K=0.38).
a) What is the velocity in ft/s for the floor heat system?
b) What is the pressure drop of the entire system?
You realize that the total pressure drop for the above system on 1 loop is too large to overcome, so you decide to create 45 loops (total length of each loop is divided equally among the 18,000 ft of floor heating pipe) within the system. The flow still exits the boiler system at 50 gpm and then is split equally among all 45 loops. Each loop contains 1 return bend and 2 couplings, before returning to the boiler system.
c) What is the velocity in ft/s in an individual loop?
d) What is the pressure drop across an individual loop?