Thermal-physical properties of air at 1 atm between temperatures of 200 K and 350 K.

air.m

classdef air < handle
    % AIR Thermal-physical properties of air at 1 atm between temperatures
    %   of 200 K and 350 K.
    % Mark Mikofski
    % Version 1-0, 2010-10-29
    properties
        description = 'air at 1 atm between 200 and 350 K'
    end
    properties
        Temp
        pRho
        pDerRho
        pMu
        pDerMu
        pK
        pDerK
        rhoi
        drhoi
        cpi
        dcpi
        ki
        dki
        mui
        dmui
        nui
        dnui
        alphai
        dalphai
        Pri
        dPri
    end
    methods
        function obj = air(Temp)
            if nargin<1,Temp = 20;end
            if ~isscalar(Temp),error('air:nonScalarTemp','Ambient temperature must be scalar.'),end
            obj.Temp = Temp + 273.15;
            % Incropera and DeWitt, Properties of Air at 1 atm
            Tdata = [200;250;300;350]; % [K]
            rhoData = [1.7458;1.3947;1.1614;0.9950]; % [kg/m^3]
            %cpData = [1.007;1.006;1.007;1.009]*1e3; % [J/kg/K]
            muData = [132.5;159.6;184.6;208.2]/1e7; % [kg/m/s]
            kData = [18.1;22.3;26.3;30.0]/1e3; % [W/m/K]
            % polynomial fits of air properties
            obj.pRho = polyfit(1./Tdata,rhoData,3);
            obj.pDerRho = polyder(obj.pRho);
            obj.pMu = polyfit(Tdata,muData,3);
            obj.pDerMu = polyder(obj.pMu);
            obj.pK = polyfit(Tdata,kData,3);
            obj.pDerK = polyder(obj.pK);
            obj.rhoi = polyval(obj.pRho,1/obj.Temp);
            obj.drhoi = polyval(obj.pDerRho,1/obj.Temp)*(-1/obj.Temp^2);
            obj.cpi = 1007;
            obj.dcpi = 0;
            obj.ki = polyval(obj.pK,obj.Temp);
            obj.dki = polyval(obj.pDerK,obj.Temp);
            obj.mui = polyval(obj.pMu,obj.Temp);
            obj.dmui = polyval(obj.pDerMu,obj.Temp);
            obj.nui = obj.mui/obj.rhoi;
            obj.dnui = obj.dmui/obj.rhoi - obj.mui*obj.drhoi/obj.rhoi^2;
            %obj.dnui = (obj.dmui*obj.rhoi - obj.mui*obj.drhoi)/obj.rhoi^2;
            obj.alphai = obj.ki/obj.rhoi/obj.cpi;
            obj.dalphai = (obj.dki/obj.rhoi - obj.ki*obj.drhoi/obj.rhoi^2)/obj.cpi;
            %dalphai = (obj.dki*obj.rhoi - obj.ki*obj.drhoi)/obj.rhoi^2/obj.cpi;
            obj.Pri = obj.nui/obj.alphai;
            obj.dPri = obj.dnui/obj.alphai - obj.nui*obj.dalphai/obj.alphai^2;
            %dPri = (obj.dnui*obj.alphai - obj.nui*obj.dalphai)/obj.alphai^2;
        end
        function obj = setTemp(obj,Temp)
            if ~isscalar(Temp),error('air:nonScalarTemp','Ambient temperature must be scalar'),end
            obj.Temp = Temp + 273.15;
            obj.rhoi = polyval(obj.pRho,1/obj.Temp);
            obj.drhoi = polyval(obj.pDerRho,1/obj.Temp)*(-1/obj.Temp^2);
            obj.cpi = 1007;
            obj.dcpi = 0;
            obj.ki = polyval(obj.pK,obj.Temp);
            obj.dki = polyval(obj.pDerK,obj.Temp);
            obj.mui = polyval(obj.pMu,obj.Temp);
            obj.dmui = polyval(obj.pDerMu,obj.Temp);
            obj.nui = obj.mui/obj.rhoi;
            obj.dnui = obj.dmui/obj.rhoi - obj.mui*obj.drhoi/obj.rhoi^2;
            %obj.dnui = (obj.dmui*obj.rhoi - obj.mui*obj.drhoi)/obj.rhoi^2;
            obj.alphai = obj.ki/obj.rhoi/obj.cpi;
            obj.dalphai = (obj.dki/obj.rhoi - obj.ki*obj.drhoi/obj.rhoi^2)/obj.cpi;
            %dalphai = (obj.dki*obj.rhoi - obj.ki*obj.drhoi)/obj.rhoi^2/obj.cpi;
            obj.Pri = obj.nui/obj.alphai;
            obj.dPri = obj.dnui/obj.alphai - obj.nui*obj.dalphai/obj.alphai^2;
            %dPri = (obj.dnui*obj.alphai - obj.nui*obj.dalphai)/obj.alphai^2;
        end
        function disp(obj)
            prop = {'Temp','rhoi','drhoi','cpi','dcpi','ki','dki', ...
                'mui','dmui','nui','dnui','alphai','dalphai','Pri','dPri'};
            propStr = {'Temp','rho','drho/dT','cp','dcp/dT','k','dk/dT', ...
                'mu','dmu/dT','nu','dnu/dT','alpha','dalpha/dT','Pr','dPr/dT'};
            propUnits = {'[K]','[kg/m^3]','[kg/m^3/K]','[J/kg/K]','[J/kg/K^2]','[W/m/K]','[W/m/K^2]', ...
                '[kg/m/s]','[kg/m/s/K]','[m^2/s]','[m^2/s/K]','[m^2/s]','[m^2/s/K]','','[1/K]'};
            for n = 1:15
                str = sprintf('%12s = %12.4g %s',propStr{n},obj.(prop{n}),propUnits{n});
                disp(str)
            end
        end
    end
end