Example 22.4 Temperature variation in a well-stirred tank 0.6kW Known: Initially 45kg liquid water, Mixing i1=270kg/h 45C rotor ·D inlet=p exit Constant liquid level unsteady Plot: -Tank Boundary ·T ater VS.t Cooling coil Paddle wheel Assumptions: m2=270kg/h ·Uniform T(t)by paddle Remove energy at rate 7.6kW ·△PE,△KE→0 cv Q only with cooling coil Water incompressible 上游究通大学 Mar/29,Wed,2017 13 SHANGHAI JIAO TONG UNIVERSITYMar/29, Wed, 2017 13 Example 22.4 Temperature variation in a well-stirred tank Known: • Initially 45kg liquid water, 45 ˚C • p inlet = p exit • unsteady Plot: • T water vs. t Assumptions: • Uniform T(t) by paddle • ∆PE, ∆KE  0 • Q only with cooling coil • Water incompressible Remove energy at rate 7.6kW Paddle wheel 0.6kW CV