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04_rankine_reheat_cycle-non-ideal.py
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04_rankine_reheat_cycle-non-ideal.py
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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
@date: 10 December 2020
This source code is provided by Richard J Smith 'as is' and 'with all faults'. The provider makes no
representations or warranties of any kind concerning the safety, suitability, inaccuracies,
typographical errors, or other harmful components of this software.
"""
import matplotlib.pyplot as plt
import numpy as np
from pyXSteam.XSteam import XSteam
steamTable = XSteam(XSteam.UNIT_SYSTEM_MKS)
print('Rankine reheat cycle analysis (non ideal)')
p1 = 0.06
s1 = steamTable.sL_p(p1)
T1 = steamTable.t_ps(p1, s1)
h1 = steamTable.hL_p(p1)
print('\nPoint 1')
print(f"T1: {round(float(T1),1)} degC")
print(f"P1: {round(float(p1),1)} bar")
print(f"H1: {round(float(h1),1)} kJ/kg")
print(f"S1: {round(float(s1),3)} kJ/kg K")
p2 = 150
s2 = s1
v = 1/steamTable.rhoL_p(p1)
w_p = v*(p2-p1)
print('\nPoint 2')
h2 = h1+w_p
print(f"H2: {round(float(h2),1)} kJ/kg")
T2 = steamTable.t_ph(p2, h2)
print(f"T2: {round(float(T2),1)} degC")
h2dash = steamTable.hL_p(p2)
s2dash = steamTable.sL_p(p2)
T2dash = steamTable.t_ph(p2, h2dash)
print('\nPoint 2dash')
print(f"T2dash: {round(float(T2dash),1)} degC")
print(f"P2dash: {round(float(p2),1)} bar")
print(f"H2dash: {round(float(h2dash),1)} kJ/kg")
print(f"S2dash: {round(float(s2dash),3)} kJ/kg K")
h3dash = steamTable.hV_p(p2)
s3dash = steamTable.sV_p(p2)
T3dash = T2dash
print('\nPoint 3dash')
print(f"T3dash: {round(float(T3dash),1)} degC")
print(f"H3dash: {round(float(h3dash),1)} kJ/kg")
print(f"S3dash: {round(float(s3dash),3)} kJ/kg K")
p3 = p2
T3 = 540
h3 = steamTable.h_pt(p3, T3)
s3 = steamTable.s_pt(p3, T3)
print('\nPoint 3')
print(f"T3: {round(float(T3),1)} degC")
print(f"P3: {round(float(p3),1)} bar")
print(f"H3: {round(float(h3),1)} kJ/kg")
print(f"S3: {round(float(s3),3)} kJ/kg K")
p4 = p2/8
print(f"Reheat Pressure: {round(float(p4),1)} bar")
s4 = s3
T4 = steamTable.t_ps(p4, s4)
h4 = steamTable.h_pt(p4, T4)
HPturbeff = 0.90 # HP turbine isentropic efficiency can be entered here (typically 0.85 - 0.95)
h4r = h3 - (HPturbeff * h3) + (HPturbeff * h4)
s4r = steamTable.s_ph(p4, h4r)
T4r = steamTable.t_ps(p4, s4r)
print('\nPoint 4')
print(f"T4ideal: {round(float(T4),1)} degC")
print(f"T4real: {round(float(T4r),1)} degC")
print(f"P4: {round(float(p4),1)} bar")
print(f"H4ideal: {round(float(h4),1)} kJ/kg")
print(f"H4real: {round(float(h4r),1)} kJ/kg")
print(f"S4ideal: {round(float(s4),3)} kJ/kg K")
print(f"S4real: {round(float(s4r ),3)} kJ/kg K")
w_HPt = h3-h4r
p5 = p4
T5 = T3
h5 = steamTable.h_pt(p5, T5)
s5 = steamTable.s_pt(p5, T5)
print('\nPoint 5')
print(f"T5: {round(float(T5),1)} degC")
print(f"P5: {round(float(p5),1)} bar")
print(f"H5: {round(float(h5),1)} kJ/kg")
print(f"S5: {round(float(s5),3)} kJ/kg K")
p6 = p1
s6 = s5
T6 = steamTable.t_ps(p6, s6)
x6 = steamTable.x_ps(p6, s6)
h6 = steamTable.h_px(p6, x6)
print('\nPoint 6')
print(f"T6: {round(float(T6),1)} degC")
print(f"P6: {round(float(p6),1)} bar")
LPturbeff = 0.90 # IP/LP turbine isentropic efficiency can be entered here (typically 0.85 - 0.95)
h6r = h5 - (LPturbeff * h5) + (LPturbeff * h6)
print(f"H6ideal: {round(float(h6),1)} kJ/kg")
print(f"H6real: {round(float(h6r),1)} kJ/kg")
s6r = steamTable.s_ph(p6, h6r)
x6r = steamTable.x_ps(p6, s6r)
print(f"S6ideal: {round(float(s6),3)} kJ/kg K")
print(f"S6real: {round(float(s6r ),3)} kJ/kg K")
print(f"x6ideal: {round(float(x6),2)} ")
print(f"x6real: {round(float(x6r),2)} ")
print('\nSummary')
print(f"Work required by pump: {round(float(w_p),1)} kJ/kg")
print(f"Work generated by HP turbine: {round(float(w_HPt),1)} kJ/kg")
w_LPt = h5-h6r
print(f"Work generated by LP turbine: {round(float(w_LPt),1)} kJ/kg")
print(f"Total work output by turbine: {round(float(w_HPt+w_LPt),1)} kJ/kg")
q_H = (h3-h2)+(h5-h4r)
print(f"Heat input by boiler: {round(float(q_H),1)} kJ/kg")
q_L = h6r-h1
print(f"Heat rejected by the condenser: {round(float(q_L),1)} kJ/kg")
eta_th = (w_HPt+w_LPt-w_p)/q_H*100
print(f"Thermal efficiency is: {round(float(eta_th),1)}%")
HRcycle = 3600*100/eta_th
print(f"HR rankine cycle: {round(float(HRcycle),1)} kJ/kWh")
font = {'family' : 'Times New Roman',
'size' : 22}
plt.figure(figsize=(15,10))
plt.title('T-s Diagram - Rankine Reheat Cycle (non ideal)')
plt.rc('font', **font)
plt.ylabel('Temperature (C)')
plt.xlabel('Entropy (s)')
plt.xlim(-2,10)
plt.ylim(0,600)
T = np.linspace(0, 373.945, 400) # range of temperatures
# saturated vapor and liquid entropy lines
svap = [s for s in [steamTable.sL_t(t) for t in T]]
sliq = [s for s in [steamTable.sV_t(t) for t in T]]
plt.plot(svap, T, 'b-', linewidth=2.0)
plt.plot(sliq, T, 'r-', linewidth=2.0)
plt.plot([s1, s2, s2dash, s3dash, s3, s4r, s5, s6r, s1],[T1, T2, T2dash, T3dash, T3, T4r, T5, T6, T1], 'black', linewidth=2.0)
plt.text(s1-.1,T1,f'(1)\nT = {round(float(T1),2)} C\nP = {round(float(p1),1)} bar \nh = {round(float(h1),1)} kJ/kg\n s = {round(float(s1),3)} kJ/kgK',
ha='right',backgroundcolor='white')
plt.text(1.6,60,f'(2)\nT = {round(float(T2),2)} C\nP = {round(float(p2),1)} bar \nh = {round(float(h2),1)} kJ/kg',
ha='left',backgroundcolor='white')
plt.text(s2dash-.15,T2dash,f"(2')\nT = {round(float(T2dash),2)} C\nP = {round(float(p2),1)} bar \nh = {round(float(h2dash),1)} kJ/kg \ns = {round(float(s2dash),3)} kJ/kgK",
ha='right',backgroundcolor='white')
plt.text(s3dash-.1,T3dash-80,f"(3')\nh = {round(float(h3dash),1)} kJ/kg \ns = {round(float(s3dash),3)} kJ/kgK",
ha='right',backgroundcolor='white')
plt.text(6.3,T3-50,f'(3)\nT = {round(float(T3),2)} C\nh = {round(float(h3),1)} kJ/kg \ns = {round(float(s3),3)} kJ/kgK',
ha='right',backgroundcolor='white')
plt.text(s4-.1,T4r-120,f'(4)\nT = {round(float(T4r),2)} C\nP = {round(float(p4),1)} bar \nh = {round(float(h4r),1)} kJ/kg \ns = {round(float(s4r),3)} kJ/kgK',
ha='right',backgroundcolor='white')
plt.text(s5+.2,T5-70,f'(5)\nT = {round(float(T5),2)} C\nh = {round(float(h5),1)} kJ/kg \ns = {round(float(s5),3)} kJ/kgK',
ha='left',backgroundcolor='white')
plt.text(s6r+.1,T6,f'(6)\nT = {round(float(T6),2)} C\nh = {round(float(h6r),1)} kJ/kg \ns = {round(float(s6r),3)} kJ/kgK \nx = {round(float(x6r),3)}',
ha='left',backgroundcolor='white')
plt.savefig('04-rankine-reheat-cycle-non-ideal-TSdiagram.png')