Performance improvement of ejector expansion refrigeration

Thermodynamic and thermoeconomic analysis and

optimization of a novel combined cooling and power (CCP)

cycle by integrating of ejector refrigeration

and Kalina cycles

Arak University of Technology – thermodynamic lab

Dr. Hajizadeh

Reza Barahmand – Sina Amiri Hezaveh

rbarahmand.com

Journal Information

2

Table of Contents

1 Introduction to paper

2 Description of cycle

development

3 Results• About abstract

• System description and assumptions

• *chemical Exergy

• Simulation of thermodynamical cycle

• Simulation Test

• Validation of Simulation and Results

4 Conclusions

3

5 Development

Introduction to paper1

• Prepose of this cycle

• Kalina cycle (KC)

• Ejector refrigeration cycle (ERC)

4

System description and assumptions2

• Inputs

• Assumptions

• Sate points

5


• Inputs

6


• Assumptions

• Energy

• The energy analysis for each control volume is conducted at steady state condition.

• The refrigerant leaving the condenser, evaporator, and separator outlet is saturated.

• Flow across the expansion valves is isenthalpic.

7


• Assumptions

• Exergy

• Since the systems and their components are at rest relative to the environment, the kinetic and potential exergy rates are neglected.

• On account for the rare chemical reactions happening and its negligible value compared with the physical exergy in organic materials, the rate of chemical exergy* is neglected.

• All outer surface of the system is at constant reference temperature. So, the rate of exergy loss is neglected.

8

*chemical Exergy


• Assumptions

• Exergy(*chemical Exergy)

9

*chemical Exergy

Energy, Environment AndSustainable Development(book)

N=14.007 g/mol

H=1.007 g/mol

O=15.008 g/mol

…………………………..

Ecch =95.5 kJ/mol

Ecch =0.0027 kJ/kg

chemical Exergy


• Sate points

❑ Dead state

10

"Dead state"

T_0 = 293 [K]

P_0 = 1 [bar]

h_0 = Enthalpy(Water,T=T_0,P=P_0)

// this is only for water

s_0 = Entropy(Water,T=T_0,P=P_0)

// dead states for the NH3H2O defined in each state


• Sate points

❑ Vapor Generator

11

"Vapor generator"

// Mass balance

m_dot_16 = 10 [kg/s]

m_dot_16 = m_dot_17

m_dot_1 = 0.3655 [kg/s]

// Assuming the inlet mass flow rate of the ejector cycle

m_dot_15 = m_dot_1

// Energy balance

// Check it afer EES

T_16 = 473.2 [K]

T_17 = T_16 - 35.4

P_16 = 1.5 [bar]

P_16 = P_17

// The procces inside the VG is constant pressure

// h_16 = Enthalpy(Water,T=T_16,P=P_16)

// h_17 = Enthalpy(Water,T=T_17,P=P_17)

h_16 = 475.8

h_17 = 439.6

T_1 = 463.2 [K]

P_1 = 1750/100 [bar]

// Assumed from the paper


• Sate points

❑ Vapor Generator

12

// the procces inside the VG is constant pressure

x_1 = 0.15

x_15 = x_1

Call NH3H2O(123, T_1, P_1,x_1 : T_100, P_100, x_100, h_1, s_1, u_1, v_1, Qu_1)

// 123=> T_1,P_1,x_1

(m_dot_16*h_16) + (m_dot_15*h_15) = (m_dot_17*h_17) + (m_dot_1*h_1)

// Entroy balance

s_16 = 6.05

s_17 = 5.97

Call NH3H2O(234, P_15, x_15, h_15 : T_15, P_1500, x_1500, h_1500, s_15, u_15, v_15, Qu_15)

// 234=> P_15,x_15,h_15

(m_dot_16*s_16) + (m_dot_16*s_16) + S_dot_gen_vg = (m_dot_17*s_17) + (m_dot_1*s_1)

// Exergy balance

Edxxxvg = S_dot_gen_vg*T_0

ex_16 = (h_16-h_0)-(T_0*(s_16-s_0))

ex_17 = (h_17-h_0)-(T_0*(s_17-s_0))


ex_1 = (h_1-h_01)-(T_0*(s_1-s_01))

ex_15 = (h_15-h_01)-(T_0*(s_15-s_01))

(m_dot_16*ex_16) + (m_dot_15*ex_15) = (m_dot_17*ex_17) + (m_dot_1*ex_1) + E_dot_dest_vg


• Sate points

❑ Separator

13

"Seprator"

// Mass balance

m_dot_2 = 0.3827*m_dot_1

m_dot_1 = m_dot_4 + m_dot_2

// Energy balance

P_4 = P_1

// the process is constant pressure

P_2 = P_1

// the process is constant pressure

T_1 = T_4

// the process is constant Temparature

T_1 = T_2

// the process is constant Temparature

Qu_4 = 0

Qu_2 = 1

Call NH3H2O(128, T_4, P_4, Qu_4 : T_400, P_400, x_4, h_4, s_4, u_4, v_4, Qu_400)

Call NH3H2O(128, T_2, P_2, Qu_2 : T_200, P_200, x_2, h_2, s_2, u_2, v_2, Qu_200)

// (m_dot_1*h_1) = (m_dot_2*h_2) + (m_dot_4*h_4)

// Entropy balance

(m_dot_1*s_1) + S_dot_gen_sep = (m_dot_2*s_2) + (m_dot_4*s_4)

// Exergy balance

Edxxxsep = S_dot_gen_sep*T_0



ex_2 = (h_2-h_02)-(T_0*(s_2-s_02))

ex_4 = (h_4-h_04)-(T_0*(s_4-s_04))

m_dot_1*ex_1 = (m_dot_4*ex_4) + (m_dot_4*ex_4) + Ex_dot_dest_sep


• Sate points

❑ Expander

14

"Expander"

// Mass balance

m_dot_3 = m_dot_2

// Energy balance

P_3 = P_2/1.5

// Pressure ratio of the Exp is 1.5

(m_dot_2*h_2) = (m_dot_3*h_3) + W_dot_exp

// h_3 is calculated from the entropy balance

// Entropy balance

// We used isentropic efficiency of turbine here

s_2 = s_3s

P_3s = P_3

x_2 = x_3

x_3s = x_3

Call NH3H2O(235, P_3s, x_3s, s_3s : T_3s, P_300s, x_300s, h_3s, s_300s, u_3s, v_3s, Qu_3s)

// 235=> P_3s,x_3s,s_3s

// eta_isen_exp: eta_isen_exp = W_real_exp/W_isen_exp

eta_isen_exp = 0.85

eta_isen_exp = (h_2 - h_3)/(h_2 - h_3s)

// eta 0.85 is one of our problem input, we just calculate h_3


(m_dot_2*s_2) + S_dot_gen_exp = (m_dot_3*s_3)

// Exergy balance

Edxxxexp = S_dot_gen_exp*T_0

ex_3 = (h_3-h_0)-(T_0*(s_3-s_0))

(m_dot_2*ex_2) = (m_dot_3*ex_3)+W_dot_exp+Ex_dot_dest_exp


• Sate points

❑ cycle

15


• Sate points

❑ Regenerator

16

"Regenarator"

// Mass balance

m_dot_5 = m_dot_4

m_dot_14 = m_dot_15

// Energy balance

P_5 = P_4

x_5 = x_4

(m_dot_4*h_4) + (m_dot_14*h_14) = (m_dot_5*h_5) + (m_dot_15*h_15)

// Entropy balance


(m_dot_4*s_4) + (m_dot_14*s_14) + S_dot_gen_rg = (m_dot_15*s_15) + (m_dot_5*s_5)

// Exergy balance

Exxxrg = S_dot_gen_rg*T_0

ex_5 = (h_5-h_04)-(T_0*(s_5-s_04))

// ex_14 = (h_14-h_01)-(T_0*(s_14-s_01))

(m_dot_4*ex_4) + (m_dot_14*ex_14) = (m_dot_15*ex_15) + (m_dot_5*ex_5) +

E_dot_dest_rg


• Sate points

❑ Expansion valve 1

17

"EX.V 1"

// Change the diagram and codes

// Mass balance

m_dot_7 = m_dot_6

// Energy balance

x_7 = x_6

P_7 = P_6 - 17.487 [kPa]

h_6 = h_7

// Entropy balance

s_6 = s_7

// Exsrgy balance

ex_7 = (h_7-h_04)-(T_0*(s_7-s_04))

(m_dot_6*ex_6) = (m_dot_7*ex_7) + E_dot_dest_exv1


• Sate points

❑ Evaporator

18

"Evaprator"


// Mass balance

m_dot_8 = m_dot_7

// Energy balance

x_8 = x_7

T_8 = 283 [K]

// Eva temprature outlet is an Input

P_8 = P_7

Call NH3H2O(123, T_8, P_8, x_8 : T_800, P_800, x_800, h_8, s_8, u_8, v_8, Qu_8)

Q_dot_cooling_eva = m_dot_7*(h_7-h_8)

(m_dot_7*s_7) + S_dot_gen_eva = (m_dot_8*s_8)

// Exergy Balanced

ex_8 = (h_8-h_04)-(T_0*(s_8-s_04))

(m_dot_8*ex_8)+(Q_dot_cooling_eva) = (m_dot_8*ex_8)+Ex_dot_dest_eva


• Sate points

❑ Ejector

19

"Ejector"


// Mass balance


// Energy balance

// m_dot_9*h_9 = (m_dot_3*h_3) + (m_dot_8*h_8)

h_9 = ((h_3/(1+mu_ejc))+((h_8*mu_ejc)/(1+mu_ejc)))

(m_dot_9*x_9) = (m_dot_3*x_3) + (m_dot_8*x_8)

// Entropy balance

mu_ejc = m_dot_8/m_dot_3

P_9 = 0.3087 [bar]

// Ejectore is designable


// Exergy balance

m_dot_9*s_9 = (m_dot_3*s_3)+(m_dot_8*s_8) + S_dot_gen_ejc

// S_dot_gen is alwasye at the inlet side of entropy balance

// Exergy Balanced


ex_9 = (h_9-h_09)-(T_0*(s_9-s_09))

(m_dot_9*ex_9) + Ex_dot_dest_ejc = (m_dot_8*ex_8) + (m_dot_3*ex_3)


• Sate points

❑ Expansion valve 2

20

"EX.V 2"


// Mass balance

m_dot_11 = m_dot_10

// Energy balance

x_11 = x_10

P_11 = P_9

h_11 = h_10

// Entropy balance

s_11 = s_10

// Exsrgy balance

ex_11 = (h_11-h_04)-(T_0*(s_11-s_04))

(m_dot_11*ex_11) = (m_dot_10*ex_10) + E_dot_dest_exv2


• Sate points

❑ Expansion valve 1,2

21

"Valve"

m_dot_6 = 0.11*m_dot_5


// Energy balance

P_6 = P_5

P_10 = P_5

x_6 = x_5

x_10 = x_5

h_6 = h_5

h_10 = h_5

// Entropy balance

s_10 = s_5

s_6 = s_5

// Exergy balance

ex_10 = ex_5

ex_6 = ex_5


• Sate points

❑ Mixer

22

"Mixer"

// Mass balance

x_12 = x_1


// Energy balance

m_dot_12*h_12 = (m_dot_11*h_11)+(m_dot_9*h_9)

// Entropy Balanced

P_12 = P_9

Call NH3H2O(234, P_12, x_12, h_12 : T_12, P_1200, x_1200, h_1200, s_12, u_12,

v_12, Qu_12)

m_dot_12*s_12 = (m_dot_11*s_11) + (m_dot_9*s_9) + S_dot_gen_mix

// Exergy Balanced

ex_12 = (h_12-h_01)-(T_0*(s_12-s_01))

m_dot_12*ex_12 = (m_dot_11*ex_11)+(m_dot_9*ex_9)+Ex_dot_dest_mix


• Sate points

❑ Condenser

23

"Condenser - Water"

// Mass balance

m_dot_13 = m_dot_12

m_dot_18 = 19.73 [kg/s]

m_dot_19 = m_dot_18

// Energy balance

x_13 = x_15

Qu_13 = 0

Q_dot_cond = m_dot_12*(h_12 - h_13)

// Saturated Liquid

P_13 = P_12

P_18 = 1 [bar]

P_19 = P_18

T_18 = 293.2 [K]

T_19 = T_18 + 5

Call NH3H2O(238, P_13, x_13, Qu_13 : T_13, P_1300, x_1300, h_13, s_13, u_13, v_13, Qu_1300)

ex_13 = (h_13-h_01)-(T_0*(s_13-s_01))

// Condenser pinch point is given


• Sate points

❑ pump

24

"Pump "

// Mass balance

// m_dot_14 = m_dot_13

// Energy balance

P_14 = 17.5 [bar]

// pressures after pumps and turbines are known and is constant

(m_dot_13*h_13)+(W_dot_pump) = m_dot_14*h_14

// h_14 is calculated from the entropy balance

// Entropy balance

// We used isentropic efficiency of pump here

s_13 = s_14s

P_14s = P_14

x_14 = x_13

x_14s = x_14

Call NH3H2O(235, P_14s, x_14s, s_14s : T_14s, P_14s00, x_14s00, h_14s, s_14s00, u_14s, v_14s, Qu_14s)

// eta_isen_pump: eta_isen_pump = W_isen_pump/W_real_pump

// eta_isen_pump = 0.85

eta_isen_pump = 0.85

eta_isen_pump = (h_14s - h_13)/(h_14 - h_13)

// eta 0.85 is one of our problem input, we just calculate h_14

// s_14


// Exergy balance

ex_14 = (h_14-h_01)-(T_0*(s_14-s_01))

(m_dot_13*ex_13)+(W_dot_Pump) = (m_dot_14*ex_14)+Ex_dot_dest_Pump


• Sate points

❑ cycle

25

Results 2

• plots

❑ The effect of vapor generator pressure on the cooling output, net power output, thermal efficiency, exergy efficiency, and SUCP of the system.

26

Results 2

• plots

❑The effect of vapor generator temperature on the cooling output, net power output, thermal efficiency, exergy efficiency, and SUCP of the system.

27

Results 2

• plots

• The effect of evaporator temperature on the cooling output, net power output, thermal efficiency, exergy efficiency, and SUCP of the system

28

Results 2

• plots

❑The effect of ammonia concentration on the cooling output, net power output, thermal efficiency, exergy efficiency, and SUCP of the system.

29

Conclusion4

• Conclusion

30

Development5

31

Development5

32

Generator → Vaper Generator

Development5

33

W_dot_net = 750 kW

Q_cooling is same with Ejector cycle

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Performance improvement of ejector expansion refrigeration