Turbine_H-S.py

"""
 The Python example to call the seuif97

 H-S(Mollier) Diagram of Steam Turbine Expansion

 6 lines:
    1.  Isobar line:p inlet
    2.  Isobar line:p outlet
    3.  isentropic line:  (p inlet ,t inlet h inlet,s inlet), (p outlet,s inlet)
    4.  Expansion line: inlet,outlet
    5.  Isobar lines
    6.  Isotherm lines   

Author:   Cheng Maohua
Email:    cmh@seu.edu.cn
"""
from seuif97 import ph2t, ps2h, pt2h, pt2s, ts2h, ps2t

import matplotlib.pyplot as plt
import numpy as np


def turbine_stage(pi, ti, pe, te):
    """ superheated steam zone """
    hi = pt2h(pi, ti)
    si = pt2s(pi, ti)
    he_isos = ps2h(pe, si)
    ishd = (hi - he_isos)
    he = pt2h(pe, te)
    se = pt2s(pe, te)
    real_hd = (hi - he)
    return hi, si, he, se, ishd, (100.0 * real_hd / ishd)


class Turbine:

    def __init__(self, pin, tin, pex, tex):
        self.pin = pin
        self.tin = tin
        self.pex = pex
        self.tex = tex

    def analysis(self):
        self.hin, self.sin, self.hex, self.sex, self.his, self.ef = turbine_stage(
            self.pin, self.tin, self.pex, self.tex)

    def expansionline(self):
        sdelta = 0.01

        # 1 Isobar pin
        s_isopin = np.array([self.sin - sdelta, self.sin + sdelta])
        h_isopin = np.array([ps2h(self.pin, s_isopin[0]),
                             ps2h(self.pin, s_isopin[1])])

        # 2 Isobar pex
        s_isopex = np.array([s_isopin[0], self.sex + sdelta])
        h_isopex = np.array([ps2h(self.pex, s_isopex[0]),
                             ps2h(self.pex, s_isopex[1])])

        # 3 isentropic lines
        h_isos = np.array([self.hin, self.hin-self.his])
        s_isos = np.array([self.sin, self.sin])

        # 4 expansion Line
        h_expL = np.array([self.hin, self.hex])
        s_expL = np.array([self.sin, self.sex])

        # plot lines
        plt.figure(figsize=(6, 9))
        plt.title("H-S(Mollier) Diagram of Steam Turbine Expansion")

        plt.plot(s_isopin, h_isopin, 'b-')  # Isobar line: pin
        plt.plot(s_isopex, h_isopex, 'b-')  # Isobar line: pex

        plt.plot(s_isos, h_isos, 'ys-')  # isoentropic line:
        plt.plot(s_expL, h_expL, 'r-', label='Expansion Line')
        plt.plot(s_expL, h_expL, 'rs')

        # Isobar lines and Isotherm lines
        s_diff = self.sex-self.sin+2 * sdelta
        isos = np.array([self.sin-sdelta + s_diff*(i/7) for i in range(8)])
        # Isobar lines to plot,MPa
        p_diff = self.pin-self.pex
        isop = np.array([self.pex+p_diff*(i/7) for i in range(8)])
        for p in isop:
            h = np.array([ps2h(p, s) for s in isos])
            plt.plot(isos, h, 'b--', lw=0.5)
            # annotate Isobar line
            txt = "%.2f MPa" % (p)
            plt.annotate(txt,
                         xy=(isos[6], h[6]), xycoords='data',
                         xytext=(+1, -10), textcoords='offset points', fontsize=6)

        # Isotherm lines to plot, ºC
        t_isos = ps2t(self.pex, self.sin)
        t_diff = self.tin - t_isos
        isot = np.array([t_isos+t_diff*(i/9) for i in range(10)])
        for t in isot:
            h = np.array([ts2h(t, s) for s in isos])
            plt.plot(isos, h, 'm', lw=0.5)
            # annotate Isotherm line
            txt = "%.2f°C" % (t)
            plt.annotate(txt,
                         xy=(isos[0], h[0]), xycoords='data',
                         xytext=(+1, -10), textcoords='offset points', fontsize=6)

        _title = 'The isentropic efficiency = ' + \
            r'$\frac{h_1-h_2}{h_1-h_{2s}}$' + '=' + \
            '{:.2f}'.format(self.ef) + '%'

        plt.legend(loc="center", bbox_to_anchor=[
                   0.6, 0.94], ncol=2, shadow=True, title=_title)

        # annotate the inlet and exlet
        txt = "%.2fMPa,%.2f°C" % (self.pin, self.tin)
        plt.annotate(txt,
                     xy=(self.sin, self.hin), xycoords='data',
                     xytext=(+1, +10), textcoords='offset points', fontsize=8,
                     arrowprops=dict(arrowstyle="->", connectionstyle="arc3,rad=.2"))

        txt = "%.2fMPa,%.2f°C" % (self.pex, self.tex)
        plt.annotate(txt,
                     xy=(self.sex, self.hex), xycoords='data',
                     xytext=(+1, +10), textcoords='offset points', fontsize=8,
                     arrowprops=dict(arrowstyle="->", connectionstyle="arc3,rad=.2"))
       # annotate h2s
        txt = "%.2fMPa,%.2f°C" % (self.pex, ph2t(self.pex, h_isos[1]))
        plt.annotate(txt,
                     xy=(self.sin, h_isos[1]), xycoords='data',
                     xytext=(+1, +10), textcoords='offset points', fontsize=8,
                     arrowprops=dict(arrowstyle="->", connectionstyle="arc3,rad=.2"))

        plt.xlabel('s(kJ/(kg.K))')
        plt.ylabel('h(kJ/kg)')
        plt.grid()
        plt.show()

    def __str__(self):
        result = ('\n  Inlet(p, t) {:>6.2f} MPa {:>6.2f} °C \n  Exlet(p, t) {:>6.2f} MPa {:>6.2f} °C \nThe isentropic efficiency: {:>5.2f}%'
                  .format(self.pin, self.tin, self.pex, self.tex, self.ef))
        return result


if __name__ == '__main__':
    pin, tin = 16.0, 535.0
    pex, tex = 3.56, 315.0
    tb1 = Turbine(pin, tin, pex, tex)
    tb1.analysis()
    print(tb1)
    tb1.expansionline()