pyCalor 1.0.3

A Python module for thermodynamic calculations for teaching thermodynamics at the University of California, Berkeley.

me40

ME40 — Thermodynamics

Department of Mechanical Engineering University of California, Berkeley

pyCalor

The software package contains classes state and process. The following is the description of their use. You can also get the built-in information by typing the following statements in the Python command line:

import thermo as th

print(th.state.__doc__)

print(th.process.__doc__)

Class state

A call

import thermo as th

st = th.state(substance, property1=value1, property2=value2, name="A")

creates an object of class state. Each such object contains the following fields:

-	name	description
st.p	pressure	(in units of kPa)
st.t	temperature	(in units of K)
st.v	specific volume	(in units of m3/kg)
st.u	specific energy	(in units of kJ/kg)
st.h	specific enthalpy	(in units of kJ/kg)
st.s	specific entropy	(in units of kJ/kg K)
st.x	quality	(fraction)
st.molW	molecular weight	(in units of kg/kmol)
st.R	gas constant	(in units of kJ/kg K)
st.substance	'water', 'air', 'nitrogen', ...	()

The property values are in the “base units”; they can be viewed by issuing a command:

state.units

Examples:

import thermo as th

th.state.units

st1 = th.state('water', p=(1,'bar'), v=0.1, name="1")

st1.plot("pv") # supported plots are: "pv","Ts","ph"

st2 = th.state('R134a', x=1, t=300, name="B")

st2.plot("Ts", isoProp="v")

st3 = th.state('air', p=(1,'Mpa'), t=(10,'c'))

st3.name = "2a"

This information can also be viewed in the programming environment;

th.state.__doc__

Class process

A call

import thermo as th pr = th.process([(state1,state2),(state2,state3),...])

creates an object of class process. An object of this class represent a simple process, from st1 to st2,

pr = th.process(st1,st2)

a simple cyclic process,

pr = th.process([(st1,st2),(st2,st3),(st3,st4),(st4,st1)]),

which can also be created as

pr = th.process(st1,st2,st3,st4,st1),

or any complex process, but for a single working fluid.

You can access process object properties by the following calls

	description
pr.StateList	returns a list of state objects
pr.isoProp(st1,st2)	returns a dictionary of {isoProperty: value,...} for process st1 → st2

Once you created process object pr, you can display its states on a thermodynamic diagram via

pr.plot('ts')

to display process pr on a T-s diagram; you may likewise to make such plot in other coordinates, like 'pv', 'ph', etc.