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Thermodynamic analysis and design data for a double-effect absorption heat pump system using four working pairs
Heat Recovery Systems & ClIP Vol. 13, No. 1, pp. 49-56, 1993
0890-4332/93 $6.00 + .00
Printed in Great Britain
Pergamon Press Ltd
T H E R M O D Y N A M I C ANALYSIS A N D DESIGN DATA FOR A DOUBLE-EFFECT ABSORPTION HEAT PUMP SYSTEM USING FOUR WORKING PAIRS S. H. WON and Y. H. KANG Solar Energy Div., Korea Institute of Energy Research, P.O. Box 5, Daedeok Science Town, Daejon, Korea
(Received 4 May 1992) Abstract--Performance analysis of a double-effect absorption heat pump system has been done for water-four working pairs (or mixture) by computer simulation. The coefficient of performance and mass flow ratio are investigated to compare these aqueous solutions [water-LiC1, water-LiBr-LiSCN, water-LiCl-CaC12-Zn(NO3)2] which was developed for only cooling, with conventional water-LiBr solution, based on mass, material and heat balance equations for each part. From this analysis, it is found that the performances of the new aqueous solutions are better than that of LiBr-water solution not only in cooling systems, but also in heating systems, although the operating temperature ranges of these new aqueous solutions are very narrow in heating. Theoretical thermodynamic performance data can be used and are given here by design data.
NOMENCLATURE
COP coefficient of performance (dimensionless) FR flow ratio (dimensionless) H M P Q T X
enthalpy per unit mass (kJ/kg) mass flow rate (kg/s) pressure (kPa) heat transfer rate (kW) temperature (K or °C) concentration of salt fraction (dimensionless)
Subscripts A C E G GC W
absorber condenser evaporator generator second stage generator working fluid (water)
INTRODUCTION A conventional heat driven double-effect absorption heat pump has been used successfully as a substitute for the electric heat pump system. As the general domestic heating system operates
10
12
HB' HE II
~C
QA Fig. I. 49
50
S. H. WON and Y. H. KANG
I
Solve for PR PR = P(Tn) PA = Pn
Input data T o , T o T E, T A Mw, XGC [-
I-
I
I Solve for
(2)
X A = X(PA,TA) J
Check operatin 8 condition and change if abnormal
I Calculate mass flow rate using mass and material balances along with heat match condition at 2nd stage generator MGc
I Specifications of P, H, X, T
L
I-
[
(1)
Calculate enthalpies at all state points using state eqn.
Solve for PC PC = P(Tc) Poe = Pc
l
I
Calculate XGC using ] material balance at 2nd stage generator
Solve for 2nd stage generator temperature T c = T(P o Xoc)
XGCN = M o • XG/Moc J
I
I
Solve for high pressure Pc = P(Toc)
(1)
t
if/Xoc N - Xoc~/10 -5
I Solve for weak ] solution concenyration [
Xol = X(PG' To)
r
/
yes Calculate heat flows and COP, FR
I Another range
I I
.~ (2)
Fig. 2.
simultaneously with the cooling system in summer, an absorption system is the one to use natural gas or other thermal energy sources and the overall COP of the system is higher for the double-eff¢ct than for the single-effect system, and the cost per air conditioning load can be reduced. As shown in Fig. 1, a double-effect absorption heat pump consists of two generators, an evaporator, a condenser and an absorber. This contains five temperature levels and three pressure level systems, although the basic operating temperatures are only four temperatures which are To, Tc, T^ and TE. If four of the operating temperatures arc chosen as the independent variables then another temperature (Toc) and three pressure conditions are determined by the thermodynamic equilibrium data: a low pressure condition prevailing in the evaporator and absorber, as determined by the evaporator temperature and medium pressure in the condenser and second-effect generator, determin¢d by the condenser temperature, the high pressure in the first-¢ff¢ct generator, as determined by the temperature in the second-effect generator. The co¢flici¢nt of performance (COP) and the flow ratio (FR) are the important design and optimizing parameters in this study. The COP of a double-¢ff¢ct absorption cooling system is the ratio of the heat load of the evaporator to the heat load of the generator: C O P = Q~/Qc.
Thermodynamic analysis and design data
51
The COP of its heating system is the ratio of the heat load of the absorber and condenser to the heat load of the generator: COP = (Q^ + Qc)/QG. FR can be defined as the ratio of the mass flow rate of the solution to the generator M^ by Grover et al. [1, 2] FR = M A Mw' and this paper is based on the method of Kaushik and Chandra [3], and Won and Lee [4] who carried out the computer analysis of the double-effect generation absorption cycle using thermal state equations. C O M P U T E R M O D E L L I N G AND P A R A M E T E R RANGES The thermodynamic equations for LiCl-water [1], MCS-water [5], LiBr-LiSCN-water [5], LiBr-water [6], the refrigerant vapour [7] and the effectiveness of the solution heat exchangers [3] are of the following form: pressure of saturated vapour pressure of solution enthalpy of saturated vapour enthalpy of solution
Pw = P = Hw = H=
Pw(T) P(X, T), (T, Ts) H(X, T),
H~- H6 /-/5--/-/6,3 vI--
H7-H8 H7-Hs,2
where state points referring to effectivenesses are shown on the appropriate cycle diagram in Fig. 1: Hij is the enthalpy of the solution at the concentration of state point i and the temperature of state j. The operating ranges used are as follows: cooling:
Tc = Tc = TE = TA =
30-140°C 30-100°C 2-10°C 30-140°C
heating:
TG = Tc = TE = TA =
30-140oc 20-100oc 10-90oc 20-140°C
effectivenesses: 0.9 mass flow rate of refrigerant: 0.01 kg/s The simulation procedure is shown in the flow chart in Fig. 2, and detailed procedure is in previous papers [4, 7]. DISCUSSION OF RESULTS The derived thermodynamic design data of all cooling systems for the double-effect system were in previous papers [4, 5, 7], and the data of LiBr solution in heating were also given [8]. The tables in this paper are only for double-effect systems in heating with other solutions.
52
S.H.
WON a n d Y. H . KANG
Table 1. Derived thermodynamic design data for absorption systems operating on water-LiBr-LiSCN for heating TG
90.0 IO0.O IlO.O 120.0 100.0 110.0 120.0 130.0 110.0 120.0 130.0 140.0 120.0 130.0 140.0 140.0 80.0 80.0 90.0 100.0 90.0 100.0 II0.0 100.0 110.0 120.0 130.0 110.0 120.0 130.0 140.0 120.0 130.0 140.0 130.0 140.0 110.0 120.0 130.0 120.0 130.0 140.0 140.0 80.0 90.0 100.0 110.0 120.0 100.0 110.0 120.0 130,0 120.0 130.0 110.0 120.0 130.0 140.0 100.0 120.0 130.0 140.0 130.0 140.0 130.0 110.0 120.0 130.0 80.0 120.0 130.0 140.0 130.0 140.0 90.0 100.0 110.0
Tc
30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 70.0 30.0 40.0 40.0 40.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 70.0 70.0 70.0 70.0 80.0 80.0 80.0 90.0 90.0 30.0 30.0 30.0 40.0 40.0 40.0 50.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 70.0 70.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 50.0 50.0 40.0 40.0 40.0,:)
Te
TA
COP
):~
Xc,c
X^
FR
To,c
Qo
Qc
QE
I0.0 IO.O lO.O lO.O 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 10.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 30.0 30.0 30.0
30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30,0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0
3.36 3.42 3.42 3.42 3.33 3.33 3.33 3.33 3.26 3.42 3.48 3.53 3.33 3.33 3.73 3.36 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.05 3.05 3.05 2.92 3.12 3.12 3.07 3.28 3.28 3.28 3.63 3.63 3.38 3.38 3.38 3.38 3.38 3.38 3.36 3.45 3.45 3.45 3.45 3.52 3.69 3.69 3.15 3.44 2.76 3.12 3.17 3.17 3.17 3.06 3.32 3.32 3.06 3.31 3.31 3.42 3.42
48.48 49.87 51.18 52.12 48.06 49.21 50.87 50.84 47.64 49.09 50.34 51.48 47.21 48.80 49.96 48.28 39.80 46.32 33.87 62.06 42.85 28.87 46.35 40.24 49.87 56.59 31.30 32.33 46.94 26.18 44.60 32.72 45.43 30.23 32.93 43.90 53.96 55.31 56.52 53.55 54.85 55.82 54.45 46.47 47.94 49.40 50.37 46.74 47.70 49.45 50.54 51.62 50.54 51.62 47.29 48.71 49.43 51.69 42.25 46.87 48.31 49.46 46.44 47.92 58.46 53.67 54.92 56.18 46.06 53.25 54.39 55.80 52.78 54.00 45.68 47.34 48.53
51.50 54.90 58.09 60.92 50.49 54.01 57.17 59.93 49.46 52.93 56.10 59.10 48.44 52.22 55.14 50.94 52.35 50.02 45.87 48.01 47.90 39.61 58.70 45.84 53.58 56.23 45.85 39.21 52.34 36.93 59.09 38.99 50.55 41.44 38.57 49.13 55.68 58.60 61.68 54.73 57.63 60.27 56.70 47.93 51.86 55.15 58.54 57.25 50.79 54.43 57.52 60.48 57.52 60.48 49.77 53.23 56.07 60.44 39.69 48.74 52.25 55.83 47.72 51.25 59.62 55.93 58.81 61.62 40.23 54.99 58.01 60.71 54.08 57.08 47.18 51.09 54.76
46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 52.57 52.57 52.57 52.57 52.57 52.57 52.57 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 57.54 51.86 51.86 51.86 51.86 51.86 51.86 51.86 51.86 51.86 44.53 44.53 44.53
9.60 6.27 6.27 6.27 11.61 11.61 11.61 11.61 14.90 7.80 5.63 4.56 21.07 21.07 6.12 10.61 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 17.90 17.90 17.90 25.37 11.39 11.39 13.73 18.53 18.53 18.53 4.44 4.44 9.33 9.33 9.33 9.33 9.33 9.33 11.25 6.75 6.75 6.75 6.75 14.36 7.57 7.57 20.05 8.68 28.62 13.73 8.46 8.46 8.46 17.57 9.43 9.43 24.40 10.93 17.83 7.79 7.79
60.66 67.29 73.87 80.97 70.16 77.17 83.16 91.96 79.65 86.17 92.83 99.58 89.19 95.45 102.24 105.11 62.25 54.87 76.68 44.29 68.28 89.24 81.60 80.35 76.08 72.69 116.05 96.53 89.60 119.25 111.03 105.69 100.81 126.18 114.97 112.08 68.95 75.13 81.51 78.41 84.70 91.55 94.15 54.66 61.47 68.05 75.25 89.91 70.70 76.77 83.74 90.60 83.74 90.60 80.20 86.78 94.39 99.21 78.10 89.71 96.25 103.11 99.25 105.71 77.73 69.48 75.86 82.17 55.22 78.95 85.56 91.59 88.51 94.98 64.69 71.25 78.26
10.71 10.58 10.58 10.58 10.86 10.86 10.86 t0.86 I 1.19 10.59 10.43 10.38 11.97 11.97 10.40 10.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 12.29 12.29 12.29 13.10 11.96 11.96 12.23 10.85 10.85 10.85 9.79 9.79 10.52 10.52 10.52 10.52 10.52 10.52 10.65 10.37 10.37 10.37 10.37 10.96 10.37 10.37 11.68 10.44 14.23 11.77 ll.60 ll.60 11.60 12.12 10.86 10.86 12.10 10.90 10.65 10.28 10.28
13.94 14.03 14.03 14.03 13.77 13.77 13.77 13,77 13.55 13.76 13.91 14.04 15.70 15.70 16,29 13.39 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 14.27 14.27 14.27 14.14 14.06 14.06 13.90 14.07 14.07 14.07 13.47 13.47 13.85 13.85 13.85 13.85 13.85 13.85 13.69 13.81 13.81 13.81 13.81 15.98 16.19 16.19 13.13 13.52 14.81 14.26 14.19 14.19 14.19 14.17 13.29 13.29 13.25 13.08 13.99 13.90 13.90
23.94 23.94 23.94 23.94 23.52 23.52 23.52 23.52 23.11 23.11 23.11 23.11 25.20 25.20 25.20 22.27 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 23.94 23.94 23.94 23.52 23.52 23.52 23.11 24.13 24.13 24.13 24.13 24.13 23.71 23.71 23.71 23.71 23.71 23.71 23.29 23.29 23.29 23.29 23.29 25.38 25.38 25.38 22.45 22.45 23.94 24.13 24.13 24.13 24.13 23.71 23.71 23.71 23.29 23.29 23.89 23.89 23.89 continued
Thermodynamic analysis and design data
To
Tc
r~
T^
COP
Xo
120.0 130.0 100.0 110.0 120.0 130.0 140.0 I00.0 120.0 130.0 140.0 130.0 140.0 140.0 130.0 140.0 120.0 130.0 140,0 130.0 140.0 140.0 100.0 110.0 120.0 130.0 140.0 I I0.0 120.0 130.0 140.0 1 I0.0 130.0 140.0 140.0 140,0 II0.0 120.0 130.0 140.0 llO.O 120.0 130.0 140.0 140.0 140.0 120.0 130.0 140.0 130.0 140.0 130.0 140.0 140.0 140.0
40.0 40.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 70.0 70.0 80.0 30.0 40.0 40.0 40.0 40.0 50.0 50.0 60.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 70.0 70.0 70.0 80.0 60.0 60.0 60.0 60.0 60.0 70.0 70.0 70,0 70.0 80.0 60.0 70.0 70.0 70,0 80.0 80.0 80.0 80.0 90.0 90.0
30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 20.0 20.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40,0 40.0 40.0 40.0 50.0 50.0 50,0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 60.0 70.0 70.0 70.0 80.0
50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 80,0 80.0 80.0 80.0 80.0 80.0 90.0 90.0 90.0 100.0
3.42 3.42 3.14 3.41 3.41 3.41 3.41 3.41 3.63 3.73 3.78 3.33 3.49 3.20 2.88 2.88 3.13 3.35 3.21 3.07 3.07 3.14 3.33 3.45 3.48 3.48 3.48 3.40 3.40 3.40 4.08 4.08 3.43 3.43 3.38 3.31 3.60 3.60 3.60 3.60 3.60 3.21 3.48 3.48 3.47 3.41 3.38 3.51 3.51 3.25 3.25 3.41 3.54 3,65 3,82
50.84 50.21 45.23 46.93 48.37 50.04 50.50 41.77 46.51 47.93 49.18 46.10 47.54 45.68 58.18 57.74 52.95 54.04 55.40 52,53 53.85 52.11 44.89 46.55 47.92 48.19 51.70 44.44 46.13 47.07 48.35 42.56 45.73 47.20 45.32 51.81 44.10 45.84 47.33 48.42 40.67 43.67 45.36 46.45 44.95 51.50 43.32 44.97 46.55 42.91 44.24 42.58 44.22 42.18 41.86
Table l--Cont. X~ ,CA 58.31 60.08 46.12 50.07 53.58 57.06 59.63 39.93 49.06 52.56 55.77 48.04 51.57 47.03 59.85 59.01 55.25 58.30 60.93 54.30 57.47 53.33 46.43 50.39 53.86 57.00 61.83 45.38 49.37 52.60 56.41 40.11 48.37 52.29 47.36 53.60 45.70 49.74 53.33 56.50 39.50 44.67 48.68 52.06 47.69 53.87 44.99 49.01 52.68 43.97 47.84 44.29 48.32 43.32 43.62
44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 56.86 56.86 51.13 51.13 51.13 5 I. 13 51.13 51.13 43.71 43.71 43.71 43.71 43.71 43.71 43.71 43,71 43.71 43.71 43.71 43.71 43.71 50.40 42.90 42.90 42.90 42.90 42.90 42.90 42.90 42.90 42.90 49.65 42.09 42.09 42.09 42.09 42.09 41.31 41.31 41.31 40.57
53
FR
Toc
Qo
Qc
P.E
7.79 7.79 29.07 9.04 9.04 9.04 9.04 9,04 10.84 6.55 4.96 13.70 7,33 18,84 20.00 27.41 13,43 8,14 6.22 17.17 17.17 24.24 17,09 7.55 5.31 5,31 5.31 27.20 27.20 27.20 4.44 4.44 10.40 10.40 13.00 16.73 16.32 16.32 16.32 16.32 16.32 25.24 8.41 8.41 9.95 12.78 15.55 7.09 7.09 23.38 23.38 14.88 6.89 21.55 14.28
83.22 93.05 74.27 80.74 87.33 93.35 101.31 78.66 90.27 96.87 103.60 99.79 106.34 109.34 78.27 87.85 79.49 86.20 92.36 88.97 95.27 98.44 74.73 81.31 88.07 96.46 99.19 84.33 90.84 98,26 105.00 86.82 100.36 106.91 109.90 98.99 84.79 91.27 97.85 104.88 89.11 94.40 100.92 108.11 110.48 99.55 94.87 101.50 107.95 104.49 111.57 104.96 111.60 114.61 115.05
10.28 10.28 11.49 10.30 10.30 10.30 10.30 10.30 10.42 10.14 10.09 10.70 10.13 11.36 13.21 13.22 11.58 10.62 11.42 11,92 11.92 12.71 10.44 10.07 10.05 10.05 10.05 11.22 11.22 11.22 9.06 9.06 10.18 10.18 10.43 11.69 10.23 10.23 10.23 10.23 10.23 10.94 9.86 9.86 9.94 11.13 10.03 9.66 9.66 10.66 10.66 9.85 9.46 10.39 9.67
13.90 13.90 13.83 13.77 13.77 13.77 13.77 13.77 16.13 16.25 16.36 13.41 13.61 13.07 14.67 13.89 14.17 13.30 14.11 14.07 14.07 16.46 13.90 13.82 13.88 13.88 13.88 16.25 16.25 16.25 15.49 15.49 13.55 13.55 13.35 16.50 16.32 16.32 16.32 16.32 16.32 13.64 13.63 13.63 13.48 16.52 13.71 13.67 13.67 13.53 13.53 13.61 13.59 17.20 17.27
23.89 23.89 23.47 23.47 23.47 23.47 23.47 23.47 25.56 25.56 25.56 22.63 22.63 22.21 24.13 23.71 23.89 23.89 23.89 23.47 23.47 25.56 23.65 23.65 23.65 23.65 23,65 25.74 25.74 25.74 25,74 25.74 22.81 22.81 22,39 25.74 25,92 25.92 25.92 25.92 25.92 22.99 22.99 22.99 22.57 25.92 23.17 23.17 23.17 22.75 22.75 22.92 22.92 26.27 26.44
Tables 1-3 list the derived thermodynamic design data of LiCI solution for each combination of four basic operating temperatures. From these results, the operating temperature ranges of these three solutions are very narrow in heating, although the C O P of the three solutions are better than that of LiBr solution. Figure 3 illustrates the effect of generator temperature on the system cooling C O P and FR for four solution pairs with generator temperature at Tc = 40°C, T^ = 20°C, TE = 6°C. It is seen generally that the C O P increases while the flow ratio decreases with an increase in generator temperature, the operation temperature ranges are different, although the exact comparison of each solutions is very difficult. In this case, the system can operate on the water-LiBr-LiSCN mixture at much higher C O P than on the other fluid combinations, and FR is also not bad in a cooling system. In the case of low generating temperature ranges the LiCl-water pair is more useful for double-effect absorption heat pumps than the other solutions [7]. Figure 4 illustrates the effect of evaporator temperature on the system cooling C O P and FR for double-effect absorption cycles with evaporator temperature at T -- 40°C, T -- 80°C and T = 20°C.
54
S. H. WoN a n d Y. H. KaNt; Table 2. Derived thermodynamic design data lbr absorption systems operating on water-LiCt lor heating TG
Tc
TE
TA
COP
X~
XGc
XA
FR
Tcc
Q¢;
Qc
QE
70.0 80,0 90.0 100.0 130.0 50.0 60.0 60.0 70.0 70.0 80.0 80.0 90.0 100.0 90.0 100.0 110.0 120.0 130.0 70.0 80.0 90.0 60.0 70.0 70.0 80.0 80.0 90.0 100,0 110,0 120,0 100,0 120,0 80,0 90,0 90,0 100,0 100.0 110.0 110.0 120.0 130.0 100.0 90.0 100.0 100.0 110.0 110.0 120.0 130.0 100.0 100.0 ll0.0 120.0
30.0 40.0 50.0 60.0 80.0 30.0 30.0 40.0 40.0 50.0 50.0 60.0 60.0 60.0 70.0 70.0 70.0 90,0 90.0 30.0 40.0 50.0 40.0 40.0 50.0 50.0 60.0 60.0 60.0 80.0 80.0 90.0 70.0 50.0 50.0 60.0 60.0 70.0 70.0 80.0 80.0 80.0 90.0 60.0 60.0 70.0 70.0 80.0 80.0 80.0 90.0 70.0 70.0 70.0
10.0 10.0 10.0 10.0 10.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0
30,0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 50.0 50.0 50,0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60,0 60.0 60.0 60.0 60.0 70.0 70.0 80.0
2,88 2.90 2.91 3.03 2.88 2.95 3.04 3.00 3.10 3.04 3.16 3.25 3.25 3.25 2.94 3.24 3.24 3.43 3.43 2.78 2.78 2.72 2.89 3.00 2.90 2.90 2.97 3,30 3.30 3.04 3.04 3.04 2.83 2.98 2.98 3.36 3.29 3.02 3.02 2.86 2.86 2.86 2.86 3.16 3,16 2.96 2.96 2.75 2.75 2.75 2.75 2.94 2.94 2.69
31.25 31.28 31.02 30.47 30.54 22.42 25.09 22.76 25.19 22,79 25.05 22.53 24.62 25.32 21.97 24.05 27.00 21.93 24.41 31.83 31.87 31.61 23.25 25.89 23.30 25.63 23.04 25.36 27.98 23.77 25.26 17.44 32.77 26.15 28.53 25.63 27.76 25.07 26.71 24.10 25.80 21.97 17.74 25.89 27.80 25.21 27.22 24.22 25.72 23.25 17.74 25.13 26.46 32.87
33.41 33.46 32.87 31.64 31.78 23.71 30.55 24.47 30.93 24.53 30,58 23.92 29.80 34.33 22.67 27.83 34.02 22.70 27.76 32.81 32.89 32.32 23.95 30.23 24.03 29.84 23.45 28.91 35.01 25.04 29.47 13.79 33.70 29.53 36.08 28.67 34.03 26.96 31.77 24.77 29.21 29.04 13.74 28.43 33.75 26.84 32.20 24.67 28.92 29.93 13.70 26.91 31.42 33.62
29.31 29,31 29.31 29.31 29.31 21.26 21.26 21.26 21.26 21.26 21,26 21.26 21.26 21.26 21.26 21.26 21.26 21.26 21.26 30.90 30.90 30.90 22.60 22.60 22.60 22.60 22.60 22.60 22.60 22.60 22.60 22.60 31.98 23.43 23.43 23.43 23.43 23.43 23.43 23.43 23.43 23.43 23.43 23.76 23.76 23.76 23.76 23.76 23.76 23.76 23.76 23.58 23.58 32.20
8.15 8.06 '4.24 13.56 12.89 9.71 3.29 7.64 3.20 7.51 3.28 9.00 9.00 9.00 16.14 4.24 4.24 15.76 15.76 17.13 16.53 22.72 17.74 3.96 16.81 16.81 27.63 4.58 4.58 10.26 10.26 10.26 19.62 4.84 4.84 5.47 3.21 7,64 7.64 18.48 18.48 18.48 18,48 6.08 6.08 8.69 8.69 26.84 26.84 26.84 26.84 8.08 8.08 23.80
51.52 60.99 70,26 79.35 102.39 41,18 48,48 51.14 58.22 60.87 67.69 70.40 76.96 84.60 79.73 85.89 90.89 103.41 108.19 50.89 60.36 69.95 50,57 57,45 60.31 67.06 69.65 76.19 81.89 94.10 100.18 92.63 92.90 66.51 72.87 75.90 82.12 84.85 91.17 93.77 99.66 110.50 92.33 75.63 82,07 84.71 90.67 93.65 99.73 109.29 92.32 84.79 91.42 92.80
13.40 13,32 !3.36 13.8l 13.89 12.74 ~2,46 12.55 12.22 12.42 11.99 12.45 12.45 12.45 /3.20 11.70 11.711 12.39 12.39 13.89 13.94 14.53 12.99 12.50 13.03 13.03 13.91 12.15 12.15 12,58 12.58 12.58 13.67 12.49 12.49 11.60 12.15 12.40 12.40 13.50 13.50 13.50 13.50 12.46 12,46 12.50 12.50 14.06 14.06 14.06 14.06 12.43 12.43 14.15
12.65 12.51 12.34 14.56 11.88 12.46 12,66 12.33 12.61 12.22 12.55 14.55 14.55 14.55 11.48 12.38 12.38 13.98 13.98 12.79 12.53 12.24 12.32 12.50 12.06 12.06 14.03 14.85 14.85 11.88 11.88 11.88 11,10 12.35 12.35 14.01 14.98 12.12 12.12 11.60 11.60 11.60 11.60 14.74 14.74 12.11 12.11 11.57 11.57 11.57 11.57 12.13 12.13 12.69
23.94 23.52 23.11 25.20 21.85 24.13 24.13 23.71 23,71 23.29 23.29 25.38 25.38 25.38 22.45 22.45 22.45 25.38 25.38 24.13 23.71 23.29 23.89 23.89 23.47 23.47 25.56 25.56 25.56 22.21 22.21 22.21 22.63 23.65 23.65 25.74 25.74 22.81 22.81 23,39 22.39 22.39 22.39 25.92 25.92 22.99 22.99 22.57 22.57 22.57 22.57 23.17 23.17 23.17
It is seen that the COP increases while the flow ratio decreases with an increase in evaporator temperature and the same tendencies are plotted as shown in Fig. 3. Figure 5 and 6 show the variation of COP and FR for the heating system of a double-effect generation cycle; these indicate that the system can operate on the water-LiBr-LiSCN mixture at much lower FR than on the others, and the COP is higher than the others. It is seen that, in the high generator temperature range (above 130°C), MCS solution is very useful although the operation temperature range is very narrow compared to water-LiBr solution.
CONCLUSIONS The thermodynamic design data of double-effect absorption heating and cooling cycles uses four aqueous solutions as working fluids. A performance analysis of a double.effect absorption heat
55
T h e r m o d y n a m i c analysis and design data
Table 3. Derived thermodynamic design data for absorption systems operating on water-MCS for heating
70
Tc
TE
T^
toe
XG
xoc
x^
FR
Tcc
tic
Qc
fie
90.0 100.0 IlO.O 120.0 130.0 140.0 Ii0.0 120.0 130.0 140.0 140.0 90.0 100.0 110.0 120.0 130.0 140.0 110.0 120.0 130.0 140.0 140.0 140.0 110.0 120.0 130.0 140.0 140.0 130.0 140.0
30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 50.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 50.0 30.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0
I0.0 I0.0 10.0 I0.0 i0.0 I0.0 I0.0 10.0 10.0 10.0 10.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0
30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0
3.35 3.43 3.47 3.50 3.53 3.56 3.22 3.35 3.57 3.57 3.02 3.34 3.40 3.43 3.46 3.48 3.50 3.24 3.48 3.48 3.59 3.06 2.91 3.27 3.27 3.27 3.27 3.28 3.22 3.46
44.31 45.35 46.19 46.89 47.52 48.17 43.76 44.56 45.07 46.21 43,43 44.27 45.31 46.14 46.85 47.50 48.15 43.71 44.40 45.39 45.53 43.37 52.13 43.53 44.33 44.85 45.01 43.12 41.91 42.43
46.69 49.34 51.61 53.65 55.62 57.70 45.41 47.38 49.21 51.14 44.67 46.74 49.38 51.65 53.69 55.65 57.73 45.46 47.51 49.28 50.81 44.72 53.58 45.60 47.73 49.43 50.50 44.90 43.72 45.40
42.54 42.54 42.54 42.54 42.54 42.54 42.54 42.54 42.54 42.54 42.54 42.44 42.44 42.44 42.44 42.44 42.44 42.44 42.44 42.44 42.44 42.44 51.24 42.04 42.04 42.04 42.04 42.04 40.64 40.64
il.24 7.25 5.69 4.83 4.25 3.81 15.80 9.78 7.38 7.38 20.95 10.88 7.11 5.61 4.77 4.21 3.78 15.06 9.37 9.37 6.07 19.63 22.96 12.78 12.78 12.78 12.78 15.66 14.19 9.55
55.88 59.86 63.60 67.11 70.37 73.30 67.10 70.62 74.20 76.47 80.85 55.93 59.92 63.67 67.17 70.41 73.34 67.17 70.85 73.70 77.55 80.94 66.98 67.42 70.96 74.53 78.38 81.33 78.93 82.38
10.72 10.47 10.38 10.33 10.29 10.25 11.38 10.84 10.00 10.00 12.65 10.64 10.47 10.41 10.38 10.36 10.34 11.19 10.17 10.17 9.88 12.27 13.05 10.87 10.87 10.87 10.87 10.94 11.06 10.07
14.14 14.24 14.37 14.51 14.64 14.76 14.21 14.30 13.81 13.81 14.52 14.17 14.23 14.34 14.46 14.58 14.69 14.29 13.73 13.73 13.89 14.64 15.81 14.30 14.30 14.30 14.30 13.98 14.47 13.76
23.94 23.94 23.94 23.94 23.94 23.94 23.52 23.52 23.52 23.52 23.11 24.13 24.13 24.13 24.13 24.13 24.13 23.71 23.71 23.71 23.71 23.29 24.13 23.89 23.89 23.89 23.89 23.47 23.65 23.65
1. 2. 3. 4.
pump system has been done. The COP and FR according to the different operating temperatures are analysed up to the crystallization limit in the generator. From these studies, we have revealed these findings: Derived thermodynamic design data for a double-effect absorption heating system operating on three aqueous solutions have been presented. The operating temperature ranges of these three solutions are very narrow in heating, although the COP of the three solutions are better than that of LiBr solution. At the low generating temperature ranges the LiCl-water pair is useful for the solution of this system. At the very high generator temperature range (above 130°C), MCS solution is very useful.
2.5
25
2.0
20
2.5
25
2.0
20
a~ 0~1.5 t,,J
~
1.0 _
0.5
?
I ~'
I I 6 0 70
~
, Mcs
I . o LiBr-LiSCI I~.o_ ~_ _ - - -1 - - - - o - LICI / ~ \ I \ \ I % '~. I \ "" ~ . - - - . - , 4 - " "" - - . n
._.FR
I I l I I I I I 80 9 0 1 0 0 1 1 0 1 2 0 1 3 0 1 4 0 1 5 0 1 6 0 T O oC
Fig. 3. HRS 13/I--E
--COP
\
:1.5
15 ¢<
ro
\
o Mcs \
\
\
1.0
x
10
_
x LiBr-LiSCN
\%
"~"
-COP " - - ]FR
0.5
-
-5 x-
--x.
I 2
I 4
I 6 T O °C Fig. 4.
I
I
8
10
I
12
I0
56
S. H. WON and Y. H. KANG 3.5
-
--35
3.~
--
--30
3.0-
25
2.5-
35
o-
i
3.0-
f
30
o LiBr
2.5-
a
--
MCS
o
0
0
2.0-
~20
COP __
1.5
FR
15
"-... ~.._
0.5 9O
I
100
t
llO
I
120
1.5
1
130
I
140
10
1.0
5
0.5~
t
150
90
T O *C
25 20
o \
\
1.0
0." 2.0 0
LiBr
MCS o LiBr-LiSCN
o LiBr-LiSCN
I
100
~
COP
---
FR
-
15
,.
I
I10
I
120
I
130
I
140
t: °
150
T O *C
Fig. 5.
Fig. 6. REFERENCES
1. G. S. Grover, S. Devotta and F. A. Holland, Thermodynamic design data for absorption heat pump systems operating on water-lithium chloridc--I. Cooling. Heat Recovery Systems & CHP g, 33-41 (1988). 2. G. S. Grover, S. Devotta and F. A. Holland, Thermodynamic design data for absorption heat pump systems operating on water-lithium chloride--II. Heating. Heat Recovery Systems & CHP 8, 419-423 (1988). 3. S. C. Kaushik and S. Chandra, Computer modeling and parametric study of a double-effect generation absorption refrigeration cycle. Energy Convers. Mgmt 25, 9-14 (1985). 4. S. H. Won and W. Y. Lee, Thermodynamic design data for double-effect absorption heat pump systems using water-lithium chloride cooling. Heat Recovery Systems & ClIP 11, 41-48 (1991). 5. S. C. Kaushik, Modeling and simulation studies on single/double-effect absorption cycle using water-multicomponent salt (MCS) mixture. Solar Energy 40, 431-441 (1988). 6. ASHRAE Handbook, 1981 Fundamentals, pp. 17-142 (1981). 7. S. H. Won and H. Lee, Simulation and thermodynamic design data study on double-effect absorption cooling cycle using water-LiBr-LiSCN mixture. Heat Recovery Systems & ClIP 11, 161-168 (1991). 8. S. H. Won et al., Thermodynamic design data for double-effect absorption heat pump systems operating on water-LiBr-heating. Solar Energy (in Korea) 9, 73-80 (1989).
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T H E R M O D Y N A M I C ANALYSIS A N D DESIGN DATA FOR A DOUBLE-EFFECT ABSORPTION HEAT PUMP SYSTEM USING FOUR WORKING PAIRS S. H. WON and Y. H. KANG Solar Energy Div., Korea Institute of Energy Research, P.O. Box 5, Daedeok Science Town, Daejon, Korea
(Received 4 May 1992) Abstract--Performance analysis of a double-effect absorption heat pump system has been done for water-four working pairs (or mixture) by computer simulation. The coefficient of performance and mass flow ratio are investigated to compare these aqueous solutions [water-LiC1, water-LiBr-LiSCN, water-LiCl-CaC12-Zn(NO3)2] which was developed for only cooling, with conventional water-LiBr solution, based on mass, material and heat balance equations for each part. From this analysis, it is found that the performances of the new aqueous solutions are better than that of LiBr-water solution not only in cooling systems, but also in heating systems, although the operating temperature ranges of these new aqueous solutions are very narrow in heating. Theoretical thermodynamic performance data can be used and are given here by design data.
NOMENCLATURE
COP coefficient of performance (dimensionless) FR flow ratio (dimensionless) H M P Q T X
enthalpy per unit mass (kJ/kg) mass flow rate (kg/s) pressure (kPa) heat transfer rate (kW) temperature (K or °C) concentration of salt fraction (dimensionless)
Subscripts A C E G GC W
absorber condenser evaporator generator second stage generator working fluid (water)
INTRODUCTION A conventional heat driven double-effect absorption heat pump has been used successfully as a substitute for the electric heat pump system. As the general domestic heating system operates
10
12
HB' HE II
~C
QA Fig. I. 49
50
S. H. WON and Y. H. KANG
I
Solve for PR PR = P(Tn) PA = Pn
Input data T o , T o T E, T A Mw, XGC [-
I-
I
I Solve for
(2)
X A = X(PA,TA) J
Check operatin 8 condition and change if abnormal
I Calculate mass flow rate using mass and material balances along with heat match condition at 2nd stage generator MGc
I Specifications of P, H, X, T
L
I-
[
(1)
Calculate enthalpies at all state points using state eqn.
Solve for PC PC = P(Tc) Poe = Pc
l
I
Calculate XGC using ] material balance at 2nd stage generator
Solve for 2nd stage generator temperature T c = T(P o Xoc)
XGCN = M o • XG/Moc J
I
I
Solve for high pressure Pc = P(Toc)
(1)
t
if/Xoc N - Xoc~/10 -5
I Solve for weak ] solution concenyration [
Xol = X(PG' To)
r
/
yes Calculate heat flows and COP, FR
I Another range
I I
.~ (2)
Fig. 2.
simultaneously with the cooling system in summer, an absorption system is the one to use natural gas or other thermal energy sources and the overall COP of the system is higher for the double-eff¢ct than for the single-effect system, and the cost per air conditioning load can be reduced. As shown in Fig. 1, a double-effect absorption heat pump consists of two generators, an evaporator, a condenser and an absorber. This contains five temperature levels and three pressure level systems, although the basic operating temperatures are only four temperatures which are To, Tc, T^ and TE. If four of the operating temperatures arc chosen as the independent variables then another temperature (Toc) and three pressure conditions are determined by the thermodynamic equilibrium data: a low pressure condition prevailing in the evaporator and absorber, as determined by the evaporator temperature and medium pressure in the condenser and second-effect generator, determin¢d by the condenser temperature, the high pressure in the first-¢ff¢ct generator, as determined by the temperature in the second-effect generator. The co¢flici¢nt of performance (COP) and the flow ratio (FR) are the important design and optimizing parameters in this study. The COP of a double-¢ff¢ct absorption cooling system is the ratio of the heat load of the evaporator to the heat load of the generator: C O P = Q~/Qc.
Thermodynamic analysis and design data
51
The COP of its heating system is the ratio of the heat load of the absorber and condenser to the heat load of the generator: COP = (Q^ + Qc)/QG. FR can be defined as the ratio of the mass flow rate of the solution to the generator M^ by Grover et al. [1, 2] FR = M A Mw' and this paper is based on the method of Kaushik and Chandra [3], and Won and Lee [4] who carried out the computer analysis of the double-effect generation absorption cycle using thermal state equations. C O M P U T E R M O D E L L I N G AND P A R A M E T E R RANGES The thermodynamic equations for LiCl-water [1], MCS-water [5], LiBr-LiSCN-water [5], LiBr-water [6], the refrigerant vapour [7] and the effectiveness of the solution heat exchangers [3] are of the following form: pressure of saturated vapour pressure of solution enthalpy of saturated vapour enthalpy of solution
Pw = P = Hw = H=
Pw(T) P(X, T), (T, Ts) H(X, T),
H~- H6 /-/5--/-/6,3 vI--
H7-H8 H7-Hs,2
where state points referring to effectivenesses are shown on the appropriate cycle diagram in Fig. 1: Hij is the enthalpy of the solution at the concentration of state point i and the temperature of state j. The operating ranges used are as follows: cooling:
Tc = Tc = TE = TA =
30-140°C 30-100°C 2-10°C 30-140°C
heating:
TG = Tc = TE = TA =
30-140oc 20-100oc 10-90oc 20-140°C
effectivenesses: 0.9 mass flow rate of refrigerant: 0.01 kg/s The simulation procedure is shown in the flow chart in Fig. 2, and detailed procedure is in previous papers [4, 7]. DISCUSSION OF RESULTS The derived thermodynamic design data of all cooling systems for the double-effect system were in previous papers [4, 5, 7], and the data of LiBr solution in heating were also given [8]. The tables in this paper are only for double-effect systems in heating with other solutions.
52
S.H.
WON a n d Y. H . KANG
Table 1. Derived thermodynamic design data for absorption systems operating on water-LiBr-LiSCN for heating TG
90.0 IO0.O IlO.O 120.0 100.0 110.0 120.0 130.0 110.0 120.0 130.0 140.0 120.0 130.0 140.0 140.0 80.0 80.0 90.0 100.0 90.0 100.0 II0.0 100.0 110.0 120.0 130.0 110.0 120.0 130.0 140.0 120.0 130.0 140.0 130.0 140.0 110.0 120.0 130.0 120.0 130.0 140.0 140.0 80.0 90.0 100.0 110.0 120.0 100.0 110.0 120.0 130,0 120.0 130.0 110.0 120.0 130.0 140.0 100.0 120.0 130.0 140.0 130.0 140.0 130.0 110.0 120.0 130.0 80.0 120.0 130.0 140.0 130.0 140.0 90.0 100.0 110.0
Tc
30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 70.0 30.0 40.0 40.0 40.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 70.0 70.0 70.0 70.0 80.0 80.0 80.0 90.0 90.0 30.0 30.0 30.0 40.0 40.0 40.0 50.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 70.0 70.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 50.0 50.0 40.0 40.0 40.0,:)
Te
TA
COP
):~
Xc,c
X^
FR
To,c
Qo
Qc
QE
I0.0 IO.O lO.O lO.O 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 10.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 30.0 30.0 30.0
30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30,0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0
3.36 3.42 3.42 3.42 3.33 3.33 3.33 3.33 3.26 3.42 3.48 3.53 3.33 3.33 3.73 3.36 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.91 3.05 3.05 3.05 2.92 3.12 3.12 3.07 3.28 3.28 3.28 3.63 3.63 3.38 3.38 3.38 3.38 3.38 3.38 3.36 3.45 3.45 3.45 3.45 3.52 3.69 3.69 3.15 3.44 2.76 3.12 3.17 3.17 3.17 3.06 3.32 3.32 3.06 3.31 3.31 3.42 3.42
48.48 49.87 51.18 52.12 48.06 49.21 50.87 50.84 47.64 49.09 50.34 51.48 47.21 48.80 49.96 48.28 39.80 46.32 33.87 62.06 42.85 28.87 46.35 40.24 49.87 56.59 31.30 32.33 46.94 26.18 44.60 32.72 45.43 30.23 32.93 43.90 53.96 55.31 56.52 53.55 54.85 55.82 54.45 46.47 47.94 49.40 50.37 46.74 47.70 49.45 50.54 51.62 50.54 51.62 47.29 48.71 49.43 51.69 42.25 46.87 48.31 49.46 46.44 47.92 58.46 53.67 54.92 56.18 46.06 53.25 54.39 55.80 52.78 54.00 45.68 47.34 48.53
51.50 54.90 58.09 60.92 50.49 54.01 57.17 59.93 49.46 52.93 56.10 59.10 48.44 52.22 55.14 50.94 52.35 50.02 45.87 48.01 47.90 39.61 58.70 45.84 53.58 56.23 45.85 39.21 52.34 36.93 59.09 38.99 50.55 41.44 38.57 49.13 55.68 58.60 61.68 54.73 57.63 60.27 56.70 47.93 51.86 55.15 58.54 57.25 50.79 54.43 57.52 60.48 57.52 60.48 49.77 53.23 56.07 60.44 39.69 48.74 52.25 55.83 47.72 51.25 59.62 55.93 58.81 61.62 40.23 54.99 58.01 60.71 54.08 57.08 47.18 51.09 54.76
46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 46.14 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 33.71 52.57 52.57 52.57 52.57 52.57 52.57 52.57 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 45.34 57.54 51.86 51.86 51.86 51.86 51.86 51.86 51.86 51.86 51.86 44.53 44.53 44.53
9.60 6.27 6.27 6.27 11.61 11.61 11.61 11.61 14.90 7.80 5.63 4.56 21.07 21.07 6.12 10.61 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 2.81 17.90 17.90 17.90 25.37 11.39 11.39 13.73 18.53 18.53 18.53 4.44 4.44 9.33 9.33 9.33 9.33 9.33 9.33 11.25 6.75 6.75 6.75 6.75 14.36 7.57 7.57 20.05 8.68 28.62 13.73 8.46 8.46 8.46 17.57 9.43 9.43 24.40 10.93 17.83 7.79 7.79
60.66 67.29 73.87 80.97 70.16 77.17 83.16 91.96 79.65 86.17 92.83 99.58 89.19 95.45 102.24 105.11 62.25 54.87 76.68 44.29 68.28 89.24 81.60 80.35 76.08 72.69 116.05 96.53 89.60 119.25 111.03 105.69 100.81 126.18 114.97 112.08 68.95 75.13 81.51 78.41 84.70 91.55 94.15 54.66 61.47 68.05 75.25 89.91 70.70 76.77 83.74 90.60 83.74 90.60 80.20 86.78 94.39 99.21 78.10 89.71 96.25 103.11 99.25 105.71 77.73 69.48 75.86 82.17 55.22 78.95 85.56 91.59 88.51 94.98 64.69 71.25 78.26
10.71 10.58 10.58 10.58 10.86 10.86 10.86 t0.86 I 1.19 10.59 10.43 10.38 11.97 11.97 10.40 10.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 8.86 12.29 12.29 12.29 13.10 11.96 11.96 12.23 10.85 10.85 10.85 9.79 9.79 10.52 10.52 10.52 10.52 10.52 10.52 10.65 10.37 10.37 10.37 10.37 10.96 10.37 10.37 11.68 10.44 14.23 11.77 ll.60 ll.60 11.60 12.12 10.86 10.86 12.10 10.90 10.65 10.28 10.28
13.94 14.03 14.03 14.03 13.77 13.77 13.77 13,77 13.55 13.76 13.91 14.04 15.70 15.70 16,29 13.39 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 13.67 14.27 14.27 14.27 14.14 14.06 14.06 13.90 14.07 14.07 14.07 13.47 13.47 13.85 13.85 13.85 13.85 13.85 13.85 13.69 13.81 13.81 13.81 13.81 15.98 16.19 16.19 13.13 13.52 14.81 14.26 14.19 14.19 14.19 14.17 13.29 13.29 13.25 13.08 13.99 13.90 13.90
23.94 23.94 23.94 23.94 23.52 23.52 23.52 23.52 23.11 23.11 23.11 23.11 25.20 25.20 25.20 22.27 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 24.13 23.94 23.94 23.94 23.52 23.52 23.52 23.11 24.13 24.13 24.13 24.13 24.13 23.71 23.71 23.71 23.71 23.71 23.71 23.29 23.29 23.29 23.29 23.29 25.38 25.38 25.38 22.45 22.45 23.94 24.13 24.13 24.13 24.13 23.71 23.71 23.71 23.29 23.29 23.89 23.89 23.89 continued
Thermodynamic analysis and design data
To
Tc
r~
T^
COP
Xo
120.0 130.0 100.0 110.0 120.0 130.0 140.0 I00.0 120.0 130.0 140.0 130.0 140.0 140.0 130.0 140.0 120.0 130.0 140,0 130.0 140.0 140.0 100.0 110.0 120.0 130.0 140.0 I I0.0 120.0 130.0 140.0 1 I0.0 130.0 140.0 140.0 140,0 II0.0 120.0 130.0 140.0 llO.O 120.0 130.0 140.0 140.0 140.0 120.0 130.0 140.0 130.0 140.0 130.0 140.0 140.0 140.0
40.0 40.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 70.0 70.0 80.0 30.0 40.0 40.0 40.0 40.0 50.0 50.0 60.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 70.0 70.0 70.0 80.0 60.0 60.0 60.0 60.0 60.0 70.0 70.0 70,0 70.0 80.0 60.0 70.0 70.0 70,0 80.0 80.0 80.0 80.0 90.0 90.0
30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 20.0 20.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40,0 40.0 40.0 40.0 50.0 50.0 50,0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 60.0 70.0 70.0 70.0 80.0
50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 60.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 80,0 80.0 80.0 80.0 80.0 80.0 90.0 90.0 90.0 100.0
3.42 3.42 3.14 3.41 3.41 3.41 3.41 3.41 3.63 3.73 3.78 3.33 3.49 3.20 2.88 2.88 3.13 3.35 3.21 3.07 3.07 3.14 3.33 3.45 3.48 3.48 3.48 3.40 3.40 3.40 4.08 4.08 3.43 3.43 3.38 3.31 3.60 3.60 3.60 3.60 3.60 3.21 3.48 3.48 3.47 3.41 3.38 3.51 3.51 3.25 3.25 3.41 3.54 3,65 3,82
50.84 50.21 45.23 46.93 48.37 50.04 50.50 41.77 46.51 47.93 49.18 46.10 47.54 45.68 58.18 57.74 52.95 54.04 55.40 52,53 53.85 52.11 44.89 46.55 47.92 48.19 51.70 44.44 46.13 47.07 48.35 42.56 45.73 47.20 45.32 51.81 44.10 45.84 47.33 48.42 40.67 43.67 45.36 46.45 44.95 51.50 43.32 44.97 46.55 42.91 44.24 42.58 44.22 42.18 41.86
Table l--Cont. X~ ,CA 58.31 60.08 46.12 50.07 53.58 57.06 59.63 39.93 49.06 52.56 55.77 48.04 51.57 47.03 59.85 59.01 55.25 58.30 60.93 54.30 57.47 53.33 46.43 50.39 53.86 57.00 61.83 45.38 49.37 52.60 56.41 40.11 48.37 52.29 47.36 53.60 45.70 49.74 53.33 56.50 39.50 44.67 48.68 52.06 47.69 53.87 44.99 49.01 52.68 43.97 47.84 44.29 48.32 43.32 43.62
44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 44.53 56.86 56.86 51.13 51.13 51.13 5 I. 13 51.13 51.13 43.71 43.71 43.71 43.71 43.71 43.71 43.71 43,71 43.71 43.71 43.71 43.71 43.71 50.40 42.90 42.90 42.90 42.90 42.90 42.90 42.90 42.90 42.90 49.65 42.09 42.09 42.09 42.09 42.09 41.31 41.31 41.31 40.57
53
FR
Toc
Qo
Qc
P.E
7.79 7.79 29.07 9.04 9.04 9.04 9.04 9,04 10.84 6.55 4.96 13.70 7,33 18,84 20.00 27.41 13,43 8,14 6.22 17.17 17.17 24.24 17,09 7.55 5.31 5,31 5.31 27.20 27.20 27.20 4.44 4.44 10.40 10.40 13.00 16.73 16.32 16.32 16.32 16.32 16.32 25.24 8.41 8.41 9.95 12.78 15.55 7.09 7.09 23.38 23.38 14.88 6.89 21.55 14.28
83.22 93.05 74.27 80.74 87.33 93.35 101.31 78.66 90.27 96.87 103.60 99.79 106.34 109.34 78.27 87.85 79.49 86.20 92.36 88.97 95.27 98.44 74.73 81.31 88.07 96.46 99.19 84.33 90.84 98,26 105.00 86.82 100.36 106.91 109.90 98.99 84.79 91.27 97.85 104.88 89.11 94.40 100.92 108.11 110.48 99.55 94.87 101.50 107.95 104.49 111.57 104.96 111.60 114.61 115.05
10.28 10.28 11.49 10.30 10.30 10.30 10.30 10.30 10.42 10.14 10.09 10.70 10.13 11.36 13.21 13.22 11.58 10.62 11.42 11,92 11.92 12.71 10.44 10.07 10.05 10.05 10.05 11.22 11.22 11.22 9.06 9.06 10.18 10.18 10.43 11.69 10.23 10.23 10.23 10.23 10.23 10.94 9.86 9.86 9.94 11.13 10.03 9.66 9.66 10.66 10.66 9.85 9.46 10.39 9.67
13.90 13.90 13.83 13.77 13.77 13.77 13.77 13.77 16.13 16.25 16.36 13.41 13.61 13.07 14.67 13.89 14.17 13.30 14.11 14.07 14.07 16.46 13.90 13.82 13.88 13.88 13.88 16.25 16.25 16.25 15.49 15.49 13.55 13.55 13.35 16.50 16.32 16.32 16.32 16.32 16.32 13.64 13.63 13.63 13.48 16.52 13.71 13.67 13.67 13.53 13.53 13.61 13.59 17.20 17.27
23.89 23.89 23.47 23.47 23.47 23.47 23.47 23.47 25.56 25.56 25.56 22.63 22.63 22.21 24.13 23.71 23.89 23.89 23.89 23.47 23.47 25.56 23.65 23.65 23.65 23.65 23,65 25.74 25.74 25.74 25,74 25.74 22.81 22.81 22,39 25.74 25,92 25.92 25.92 25.92 25.92 22.99 22.99 22.99 22.57 25.92 23.17 23.17 23.17 22.75 22.75 22.92 22.92 26.27 26.44
Tables 1-3 list the derived thermodynamic design data of LiCI solution for each combination of four basic operating temperatures. From these results, the operating temperature ranges of these three solutions are very narrow in heating, although the C O P of the three solutions are better than that of LiBr solution. Figure 3 illustrates the effect of generator temperature on the system cooling C O P and FR for four solution pairs with generator temperature at Tc = 40°C, T^ = 20°C, TE = 6°C. It is seen generally that the C O P increases while the flow ratio decreases with an increase in generator temperature, the operation temperature ranges are different, although the exact comparison of each solutions is very difficult. In this case, the system can operate on the water-LiBr-LiSCN mixture at much higher C O P than on the other fluid combinations, and FR is also not bad in a cooling system. In the case of low generating temperature ranges the LiCl-water pair is more useful for double-effect absorption heat pumps than the other solutions [7]. Figure 4 illustrates the effect of evaporator temperature on the system cooling C O P and FR for double-effect absorption cycles with evaporator temperature at T -- 40°C, T -- 80°C and T = 20°C.
54
S. H. WoN a n d Y. H. KaNt; Table 2. Derived thermodynamic design data lbr absorption systems operating on water-LiCt lor heating TG
Tc
TE
TA
COP
X~
XGc
XA
FR
Tcc
Q¢;
Qc
QE
70.0 80,0 90.0 100.0 130.0 50.0 60.0 60.0 70.0 70.0 80.0 80.0 90.0 100.0 90.0 100.0 110.0 120.0 130.0 70.0 80.0 90.0 60.0 70.0 70.0 80.0 80.0 90.0 100,0 110,0 120,0 100,0 120,0 80,0 90,0 90,0 100,0 100.0 110.0 110.0 120.0 130.0 100.0 90.0 100.0 100.0 110.0 110.0 120.0 130.0 100.0 100.0 ll0.0 120.0
30.0 40.0 50.0 60.0 80.0 30.0 30.0 40.0 40.0 50.0 50.0 60.0 60.0 60.0 70.0 70.0 70.0 90,0 90.0 30.0 40.0 50.0 40.0 40.0 50.0 50.0 60.0 60.0 60.0 80.0 80.0 90.0 70.0 50.0 50.0 60.0 60.0 70.0 70.0 80.0 80.0 80.0 90.0 60.0 60.0 70.0 70.0 80.0 80.0 80.0 90.0 70.0 70.0 70.0
10.0 10.0 10.0 10.0 10.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0 60.0
30,0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 50.0 50.0 50,0 50.0 50.0 50.0 50.0 60.0 60.0 60.0 60,0 60.0 60.0 60.0 60.0 70.0 70.0 80.0
2,88 2.90 2.91 3.03 2.88 2.95 3.04 3.00 3.10 3.04 3.16 3.25 3.25 3.25 2.94 3.24 3.24 3.43 3.43 2.78 2.78 2.72 2.89 3.00 2.90 2.90 2.97 3,30 3.30 3.04 3.04 3.04 2.83 2.98 2.98 3.36 3.29 3.02 3.02 2.86 2.86 2.86 2.86 3.16 3,16 2.96 2.96 2.75 2.75 2.75 2.75 2.94 2.94 2.69
31.25 31.28 31.02 30.47 30.54 22.42 25.09 22.76 25.19 22,79 25.05 22.53 24.62 25.32 21.97 24.05 27.00 21.93 24.41 31.83 31.87 31.61 23.25 25.89 23.30 25.63 23.04 25.36 27.98 23.77 25.26 17.44 32.77 26.15 28.53 25.63 27.76 25.07 26.71 24.10 25.80 21.97 17.74 25.89 27.80 25.21 27.22 24.22 25.72 23.25 17.74 25.13 26.46 32.87
33.41 33.46 32.87 31.64 31.78 23.71 30.55 24.47 30.93 24.53 30,58 23.92 29.80 34.33 22.67 27.83 34.02 22.70 27.76 32.81 32.89 32.32 23.95 30.23 24.03 29.84 23.45 28.91 35.01 25.04 29.47 13.79 33.70 29.53 36.08 28.67 34.03 26.96 31.77 24.77 29.21 29.04 13.74 28.43 33.75 26.84 32.20 24.67 28.92 29.93 13.70 26.91 31.42 33.62
29.31 29,31 29.31 29.31 29.31 21.26 21.26 21.26 21.26 21.26 21,26 21.26 21.26 21.26 21.26 21.26 21.26 21.26 21.26 30.90 30.90 30.90 22.60 22.60 22.60 22.60 22.60 22.60 22.60 22.60 22.60 22.60 31.98 23.43 23.43 23.43 23.43 23.43 23.43 23.43 23.43 23.43 23.43 23.76 23.76 23.76 23.76 23.76 23.76 23.76 23.76 23.58 23.58 32.20
8.15 8.06 '4.24 13.56 12.89 9.71 3.29 7.64 3.20 7.51 3.28 9.00 9.00 9.00 16.14 4.24 4.24 15.76 15.76 17.13 16.53 22.72 17.74 3.96 16.81 16.81 27.63 4.58 4.58 10.26 10.26 10.26 19.62 4.84 4.84 5.47 3.21 7,64 7.64 18.48 18.48 18.48 18,48 6.08 6.08 8.69 8.69 26.84 26.84 26.84 26.84 8.08 8.08 23.80
51.52 60.99 70,26 79.35 102.39 41,18 48,48 51.14 58.22 60.87 67.69 70.40 76.96 84.60 79.73 85.89 90.89 103.41 108.19 50.89 60.36 69.95 50,57 57,45 60.31 67.06 69.65 76.19 81.89 94.10 100.18 92.63 92.90 66.51 72.87 75.90 82.12 84.85 91.17 93.77 99.66 110.50 92.33 75.63 82,07 84.71 90.67 93.65 99.73 109.29 92.32 84.79 91.42 92.80
13.40 13,32 !3.36 13.8l 13.89 12.74 ~2,46 12.55 12.22 12.42 11.99 12.45 12.45 12.45 /3.20 11.70 11.711 12.39 12.39 13.89 13.94 14.53 12.99 12.50 13.03 13.03 13.91 12.15 12.15 12,58 12.58 12.58 13.67 12.49 12.49 11.60 12.15 12.40 12.40 13.50 13.50 13.50 13.50 12.46 12,46 12.50 12.50 14.06 14.06 14.06 14.06 12.43 12.43 14.15
12.65 12.51 12.34 14.56 11.88 12.46 12,66 12.33 12.61 12.22 12.55 14.55 14.55 14.55 11.48 12.38 12.38 13.98 13.98 12.79 12.53 12.24 12.32 12.50 12.06 12.06 14.03 14.85 14.85 11.88 11.88 11.88 11,10 12.35 12.35 14.01 14.98 12.12 12.12 11.60 11.60 11.60 11.60 14.74 14.74 12.11 12.11 11.57 11.57 11.57 11.57 12.13 12.13 12.69
23.94 23.52 23.11 25.20 21.85 24.13 24.13 23.71 23,71 23.29 23.29 25.38 25.38 25.38 22.45 22.45 22.45 25.38 25.38 24.13 23.71 23.29 23.89 23.89 23.47 23.47 25.56 25.56 25.56 22.21 22.21 22.21 22.63 23.65 23.65 25.74 25.74 22.81 22.81 23,39 22.39 22.39 22.39 25.92 25.92 22.99 22.99 22.57 22.57 22.57 22.57 23.17 23.17 23.17
It is seen that the COP increases while the flow ratio decreases with an increase in evaporator temperature and the same tendencies are plotted as shown in Fig. 3. Figure 5 and 6 show the variation of COP and FR for the heating system of a double-effect generation cycle; these indicate that the system can operate on the water-LiBr-LiSCN mixture at much lower FR than on the others, and the COP is higher than the others. It is seen that, in the high generator temperature range (above 130°C), MCS solution is very useful although the operation temperature range is very narrow compared to water-LiBr solution.
CONCLUSIONS The thermodynamic design data of double-effect absorption heating and cooling cycles uses four aqueous solutions as working fluids. A performance analysis of a double.effect absorption heat
55
T h e r m o d y n a m i c analysis and design data
Table 3. Derived thermodynamic design data for absorption systems operating on water-MCS for heating
70
Tc
TE
T^
toe
XG
xoc
x^
FR
Tcc
tic
Qc
fie
90.0 100.0 IlO.O 120.0 130.0 140.0 Ii0.0 120.0 130.0 140.0 140.0 90.0 100.0 110.0 120.0 130.0 140.0 110.0 120.0 130.0 140.0 140.0 140.0 110.0 120.0 130.0 140.0 140.0 130.0 140.0
30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 50.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 50.0 30.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0
I0.0 I0.0 10.0 I0.0 i0.0 I0.0 I0.0 10.0 10.0 10.0 10.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0
30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 40.0 50.0 50.0 50.0 50.0 50.0 50.0 60.0 60.0
3.35 3.43 3.47 3.50 3.53 3.56 3.22 3.35 3.57 3.57 3.02 3.34 3.40 3.43 3.46 3.48 3.50 3.24 3.48 3.48 3.59 3.06 2.91 3.27 3.27 3.27 3.27 3.28 3.22 3.46
44.31 45.35 46.19 46.89 47.52 48.17 43.76 44.56 45.07 46.21 43,43 44.27 45.31 46.14 46.85 47.50 48.15 43.71 44.40 45.39 45.53 43.37 52.13 43.53 44.33 44.85 45.01 43.12 41.91 42.43
46.69 49.34 51.61 53.65 55.62 57.70 45.41 47.38 49.21 51.14 44.67 46.74 49.38 51.65 53.69 55.65 57.73 45.46 47.51 49.28 50.81 44.72 53.58 45.60 47.73 49.43 50.50 44.90 43.72 45.40
42.54 42.54 42.54 42.54 42.54 42.54 42.54 42.54 42.54 42.54 42.54 42.44 42.44 42.44 42.44 42.44 42.44 42.44 42.44 42.44 42.44 42.44 51.24 42.04 42.04 42.04 42.04 42.04 40.64 40.64
il.24 7.25 5.69 4.83 4.25 3.81 15.80 9.78 7.38 7.38 20.95 10.88 7.11 5.61 4.77 4.21 3.78 15.06 9.37 9.37 6.07 19.63 22.96 12.78 12.78 12.78 12.78 15.66 14.19 9.55
55.88 59.86 63.60 67.11 70.37 73.30 67.10 70.62 74.20 76.47 80.85 55.93 59.92 63.67 67.17 70.41 73.34 67.17 70.85 73.70 77.55 80.94 66.98 67.42 70.96 74.53 78.38 81.33 78.93 82.38
10.72 10.47 10.38 10.33 10.29 10.25 11.38 10.84 10.00 10.00 12.65 10.64 10.47 10.41 10.38 10.36 10.34 11.19 10.17 10.17 9.88 12.27 13.05 10.87 10.87 10.87 10.87 10.94 11.06 10.07
14.14 14.24 14.37 14.51 14.64 14.76 14.21 14.30 13.81 13.81 14.52 14.17 14.23 14.34 14.46 14.58 14.69 14.29 13.73 13.73 13.89 14.64 15.81 14.30 14.30 14.30 14.30 13.98 14.47 13.76
23.94 23.94 23.94 23.94 23.94 23.94 23.52 23.52 23.52 23.52 23.11 24.13 24.13 24.13 24.13 24.13 24.13 23.71 23.71 23.71 23.71 23.29 24.13 23.89 23.89 23.89 23.89 23.47 23.65 23.65
1. 2. 3. 4.
pump system has been done. The COP and FR according to the different operating temperatures are analysed up to the crystallization limit in the generator. From these studies, we have revealed these findings: Derived thermodynamic design data for a double-effect absorption heating system operating on three aqueous solutions have been presented. The operating temperature ranges of these three solutions are very narrow in heating, although the COP of the three solutions are better than that of LiBr solution. At the low generating temperature ranges the LiCl-water pair is useful for the solution of this system. At the very high generator temperature range (above 130°C), MCS solution is very useful.
2.5
25
2.0
20
2.5
25
2.0
20
a~ 0~1.5 t,,J
~
1.0 _
0.5
?
I ~'
I I 6 0 70
~
, Mcs
I . o LiBr-LiSCI I~.o_ ~_ _ - - -1 - - - - o - LICI / ~ \ I \ \ I % '~. I \ "" ~ . - - - . - , 4 - " "" - - . n
._.FR
I I l I I I I I 80 9 0 1 0 0 1 1 0 1 2 0 1 3 0 1 4 0 1 5 0 1 6 0 T O oC
Fig. 3. HRS 13/I--E
--COP
\
:1.5
15 ¢<
ro
\
o Mcs \
\
\
1.0
x
10
_
x LiBr-LiSCN
\%
"~"
-COP " - - ]FR
0.5
-
-5 x-
--x.
I 2
I 4
I 6 T O °C Fig. 4.
I
I
8
10
I
12
I0
56
S. H. WON and Y. H. KANG 3.5
-
--35
3.~
--
--30
3.0-
25
2.5-
35
o-
i
3.0-
f
30
o LiBr
2.5-
a
--
MCS
o
0
0
2.0-
~20
COP __
1.5
FR
15
"-... ~.._
0.5 9O
I
100
t
llO
I
120
1.5
1
130
I
140
10
1.0
5
0.5~
t
150
90
T O *C
25 20
o \
\
1.0
0." 2.0 0
LiBr
MCS o LiBr-LiSCN
o LiBr-LiSCN
I
100
~
COP
---
FR
-
15
,.
I
I10
I
120
I
130
I
140
t: °
150
T O *C
Fig. 5.
Fig. 6. REFERENCES
1. G. S. Grover, S. Devotta and F. A. Holland, Thermodynamic design data for absorption heat pump systems operating on water-lithium chloridc--I. Cooling. Heat Recovery Systems & CHP g, 33-41 (1988). 2. G. S. Grover, S. Devotta and F. A. Holland, Thermodynamic design data for absorption heat pump systems operating on water-lithium chloride--II. Heating. Heat Recovery Systems & CHP 8, 419-423 (1988). 3. S. C. Kaushik and S. Chandra, Computer modeling and parametric study of a double-effect generation absorption refrigeration cycle. Energy Convers. Mgmt 25, 9-14 (1985). 4. S. H. Won and W. Y. Lee, Thermodynamic design data for double-effect absorption heat pump systems using water-lithium chloride cooling. Heat Recovery Systems & ClIP 11, 41-48 (1991). 5. S. C. Kaushik, Modeling and simulation studies on single/double-effect absorption cycle using water-multicomponent salt (MCS) mixture. Solar Energy 40, 431-441 (1988). 6. ASHRAE Handbook, 1981 Fundamentals, pp. 17-142 (1981). 7. S. H. Won and H. Lee, Simulation and thermodynamic design data study on double-effect absorption cooling cycle using water-LiBr-LiSCN mixture. Heat Recovery Systems & ClIP 11, 161-168 (1991). 8. S. H. Won et al., Thermodynamic design data for double-effect absorption heat pump systems operating on water-LiBr-heating. Solar Energy (in Korea) 9, 73-80 (1989).