Component 508: Flow Merge by HVACSIM+ General Description This component models the merging of two flow streams. It calculates the mass flow rate and temperature of the single outlet flow stream, and the pressures at the two inlets. The model assumes that the flow resistance parameter is the same for all three branches. Nomenclature K - flow resistance coefficient P - pressure T - temperature w - mass flow rate of fluid Subscripts 1 - first inlet 2 - second inlet 3 - outlet Mathematical Description The outlet mass flow rate is simply the sum of the inlet flow rates: w3 = w1 + w2 The outlet temperature is a weighted average of the inlet temperatures: T3 = (w1*T1 + w2*T2)/w3 Inlet pressures are calculated from the outlet pressure, the flow rates, and the flow resistance coefficient: P1 = P3 + (K/2)*[sign(w1)*w1^2 + sign(w3)*w3^2] P2 = P3 + (K/2)*[sign(w2)*w2^2 + sign(w3)*w3^2] Component 508 Configuration Inputs Description 1 w1 - flow rate at first inlet 2 w2 - flow rate at second inlet 3 P3 - pressure at outlet 4 T1 - temperature at first inlet 5 T2 - temperature at second inlet Outputs Description 1 w3 - flow rate at outlet 2 P1 - pressure at first inlet 3 P2 - pressure at second inlet 4 T3 - temperature at outlet Parameters Description 1 K - flow resistance coefficient Reference: 1. HVACSIM+ Building Systems and Equipment Simulation Program Reference Manual (NBSIR 84-2996) Daniel R. Clark United States Department of Commerce National Institute of Standards and Technology Gaithersburg, Maryland 20899-0001