Component 207: Fan or Pump by HVACSIM+ General Description The pump or fan model calculates a pressure rise and an efficiency as functions of a mass flow rate, using dimensionless performance curves. The performance curves are represented by polynomials, with empirically determined coefficients which must be supplied by the user. The efficiency is used to compute a temperature rise across the fan or pump, as well as power consumption. The last parameter, MODE, determines whether air or water properties (density and specific heat) are to be used. Nomenclature Cf - dimensionless flow coefficient Ch - dimensionless pressure head coefficient Cp - specific heat of fluid (kJ/kg-C) D - diameter of blades or impeller (m) E - power consumption (kW) N - rotational speed (rps) Pi - inlet pressure (kPa) Po - outlet pressure (kPa) Ti - inlet temperature (C) To - outlet temperature w - mass flow rate (kg/s) n - efficiency p - fluid density (kg/m^3) Mathematical Description The dimensionless flow coefficient and the dimensionless pressure head coefficient are defined as follows: Cf=w/(pN(D^3)) Ch=1000*DeltaP/(p(N^2)(D^2)) where DeltaP is the pressure rise, Po - Pi, in kilopascals. The factor of 1000 converts the pressure difference from pascals to kilopascals for dimensional consistency. For this reason, the units given in the nomenclature section must be used. The model determines the head coefficient, Ch, and the efficiency, n, as functions of the flow coefficient, Cf: Ch=a0 + a1Cf + a2(Cf^2) + a3(Cf^3) + a4(Cf^4) n=e0 + e1Cf + e2(Cf^2) + e3(Cf^3) + e4(Cf^4) The 'a' and 'e' coefficients must be supplied as parameters by the users. The inlet pressure is then obtained from the definition of Ch: Pi=Po - 0.001(Ch)p(N^2)(D^2) The efficiency is used to compute power consumption, and a temperature rise is calculated on the assumption that all inefficiencies heat the fluid: E=w(DeltaP)/(np) To=Ti + (Po-Pi)/(p(Cp))*(1/n-1) Component 507 Configuration Inputs Description 1 w - fluid mass flow rate (kg/s) 2 Po - outlet pressure (kPa) 3 N - rotational speed (rps) 4 Ti - inlet temperature (C) Outputs Description 1 Pi - inlet pressure (kPa) 2 To - outlet temperature (C) 3 E - power consumption (kW) Parameters Description 1-5 ai - coefficients for head vs. flow curve 6-10 ei - coefficients for efficiency curve 11 D - diameter (m) 12 Mode - air=1, water=2 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