calebbell / ht Goto Github PK

Hi,

as the title says, both the terms heat capacity rate ratio and heat capacity ratio seem to be used in the documentation. Can someone elaborate on if there is a difference or both is the ratio of (m * cp)? I feel like publications are also not always clear.

On a connected sidenote, sometimes this is specified with ...with respect to stream 1 - does this mean that stream 1 is in the denominator?

The documented exponent for the Nu_horizontal_plate_turbulent_Kreith method is given as 2/3 when the correct value, and implemented value, is 1/3

Hi - I believe the ht.conv_free_enclosed methods such as conv_free_enclosed.Nu_Nusselt_Rayleigh_Hollands are for horizontal plates. It's not entirely clear from the docs so that should be made clear but in any case I was wondering if there are similar methods for vertical plates?
Thanks
Jeremy

First off, incredible work with this package! I'm extremely impressed with how thorough, detailed, and well-validated it is.

I have found two errors in the NTU Method functions:

1.) The P_NTU_method function gives a divide-by-zero error if the flow rate and heat capacity of both fluids are identical in counterflow (R1 = R2 = 1). This can be traced back to the following code in the temperature_effectiveness_basic function:

if subtype == 'counterflow': # Same as TEMA 1 pass P1 = (1.0 - exp(-NTU1*(1 - R1)))/(1.0 - R1*exp(-NTU1*(1-R1)))

2. The effectiveness_NTU_method function returns an error if any of the temperatures are exactly equal to 0. This can cause issues if you are working in Celsius or Fahrenheit rather than Kelvin.

Hi,
just tried the following example from the tutorial:

from ht import *

U = 275 # W/m^2/K
A = 10.82 # m^2
Cp_oil = 1900 # J/kg/K
Cp_steam = 1860 # J/kg/K
m_steam = 5.2 # kg/s
m_oil = 0.725 # kg/s
Thi = 130 # °C
Tci = 15 # °C
Cmin = calc_Cmin(mh=m_steam, mc=m_oil, Cph=Cp_steam, Cpc=Cp_oil)
Cmax = calc_Cmax(mh=m_steam, mc=m_oil, Cph=Cp_steam, Cpc=Cp_oil)
Cr = calc_Cr(mh=m_steam, mc=m_oil, Cph=Cp_steam, Cpc=Cp_oil)
NTU = NTU_from_UA(UA=U*A, Cmin=Cmin)
eff = effectiveness_from_NTU(NTU=NTU, Cr=Cr, subtype='crossflow, mixed Cmax')
Q = eff*Cmin*(Thi - Tci)
Tco = Tci + Q/(m_oil*Cp_oil)
Tho = Thi - Q/(m_steam*Cp_steam)

print(Tco,Tho)

I end up with an error:

Traceback (most recent call last):
  File "test_ht.py", line 1, in <module>
    from ht import *
  File "/usr/lib/python3/dist-packages/ht/__init__.py", line 25, in <module>
    from . import hx
  File "/usr/lib/python3/dist-packages/ht/hx.py", line 28, in <module>
    from fluids.numerics import horner, newton, ridder, quad, secant, quad, bisect
ImportError: cannot import name 'quad' from 'fluids.numerics' (/usr/lib/python3/dist-packages/fluids/numerics/__init__.py)