Page 364 - Defrosting for Air Source Heat Pump

360 Appendices

if sfrost(j,i)>=0.35;
sfrost(j,i)=0.35; % kg
mf(j,i)=0; % at fourth stage, the mf is always 0 kg/s
kTw1=Tw(j-1,i); % the initial values are different for each
circuit, °C
mr0=0.008 ; % the water left on the first coil, kg/s
smvaw=smvaw(j-1,i); % at the beginning of this stage,
it is 0 kg
% Coef7=-5800.2206;
% Coef8=1.3914993;
% Coef9=-0.04860239;
% Coef10=0.000041764768;
% Coef11=-0.000000014452093;
% Coef12=6.5459673;
T=Tri(j,i)+273.15; % K
denspipe=exp(-5800.2206*T.^(-1)+1.3914993*T.^(0)-
0.04860239*T.^(1)+0.000041764768*T.^(2)-0.000000014452093*T.^(3)
+6.5459673*log(T))/(8314./18.*T);
% calculate the density of humidity air, kg/m 3
Tair=0+273.15;% K; %Tair=0; % °C;
PwSat_Air=exp(-5800.2206*Tair.^(-1)+1.3914993*Tair.^(0)-
0.04860239*Tair.^(1)+0.000041764768*Tair.^(2)-
0.000000014452093*Tair.^(3)+6.5459673*log(Tair)); % Pa;
dens_air=0.80*PwSat_Air/(8314/18*(273.15+0));
% relative_Humi_air=0.80;
% 0.0039 density of component outside boundary layer, kg/m 3
% PwSat_pipeAir(1,t)=Pressure_Air_Water(Tr(1,t));
% dens_pipe(c,t)=Pressure_Air_Water(Tw(c,t-1)).*10^6./
(8314./18.*(273.15+Tw(c,t-1)));
% density of gas at interface (saturation density), kg/m 3

kTri=Tri(j,i); % °C
2
kRr=Rr(j,i); % (K m )/W
kMr=Mr(j,i); % kg/s
khri=hri(j,i); % kJ/kg
% all the input parameters in the function listed here
x0=[0.0042 0.0042 0.335 1200 0.001];
options=optimset(’display’,’off’,’MaxIter’,10000,
’MaxFunEvals’,20000); % number
[A,fval,exit]=fsolve(@(x)mystage42(x,kTw1,mr0,smvaw,i,
denspipe,dens_air,kTri,kRr,kMr,khri),x0,options);
mrw(j,i)=A(1); % retained water, kg/s;
mvaw(j,i)=A(2); % vaporized water, kg/s;
Tw(j,i)=A(3); % retained water temperature, °C;
qr(j,i)=A(4); % energy used in defrosting from refrigerant, W;
Tro(j,i)=A(5); % the temperature of tube surface at exit of
each circuit, °C