#VALUE in Nu Correlation Function

Hi All,
I don't know why this code returns #VALUE. Can you please help me?
Even I replaced the Do Until loop part with direct equation i.e. something like Nu_Hashmi = 5*Re but still having this #VALUE return from my function.

Function Nu_Hashmi(Re, Pr, Dh, Ah, Q, Tbulk)'Nusselt Correlation given at Empirical Nusselt Number Correlation for Single Phase Flow through a Plate Heat Exchanger




'Limitations: 500<Re<4500 ; 5.6<Pr<8.0 ; Chevron Angle = 45




tc = tcL_T(Tbulk)




If (Re > 500 And Re < 4500) And (Pr > 5.6 And Pr < 8) Then




    C1 = 0.0566
    p = 0.881
    C3 = 1 / 3
    
Else




    Nu_Hashmi = "OoR"
    GoTo 10
End If




Tsurf_temp = Tbulk * 1.1
Error = 10
    
Do Until Error < 0.001




    Nu_Hashmi = C1 * Re ^ p * Pr ^ C3 * (my_pT(4, Tbulk) / my_pT(4, Tsurf_temp)) ^ 0.14
    h = Nu_Hashmi * tc / Dh
    Tsurface = Q / h / Ah + Tbulk
    Error = Abs(Tsurface - Tsurf_temp)
    Tsurf_temp = Tsurface




Loop
10
   
End Function

Re: #VALUE in Nu Correlation Function

Quote from pike;794254

Hello HumanEngineer,
What are the functions tcL_T and my_pT ?

They are functions by XSteam (returning water properties for input temperature and pressure values). In order to simplify the add-in function calling, I just copied the XSteam module from the add-in section to my excel modules so I can easily call XSteam functions. I just checked by simple custom functions to check if the tcL_T and my_pT are the cause for this error of #VALUE return from the main function as:

Function pala(T)


'pala = tcL_T(T)
pala = my_pT(4, T)




End Function

They returns as they suppose to do.

Re: #VALUE in Nu Correlation Function

For ease of following my code, you can use the value of 1 for

my_pT(4, Tbulk) / my_pT(4, Tsurf_temp)

and for tcL_T(Tbulk) the value of 0.64
Regards.

Re: #VALUE in Nu Correlation Function

Thanks a lot for your help and for making me learn the trick of 'Exit Function' instead of my habit with using of 'goto 10 (any number)'. I become happy for this exit function trick more than my problem get solved.