Use the Kedzierski (2003) refrigerant/lubricant mixture pool boiling model to predict the boiling heat transfer coefficient (hm) for a range of superheats (47s = 8 K to 40 K) and Ts=277.6 K: 5.9x107(1-x)ph ATk₁ (1-¹) x, To Where 1 = Г PL-PX h = 9m T-T x. To 5.9x107(1-x₂)ph AT, 0.7551 p₁ (1-x)_18.75AP₁ (1-x₂) 18.75×10¯¹º[m]p, (1-x) XpPr Xp Pr XpPrv KL (W/mK) 0.139 = Assume that λ = 1.34 for xb = 0.005 and that λ = 0.3 for xb = 0.02. The properties of the refrigerant (R123) at the film temperature are: = hfg (J/kg) R123 Or (N/m) 179692.3 0.01764 The properties of the mineral oil (lubricant) are: PL (kg/m³) 917.8 York-C VL (cSt) 60 Prv (kg/m³) 2.701 VL (m²/s) 6 x 10-5 OL (N/m) 0.026 1.) Plot hm vs ATs and le vs ATs for two lubricant mass fractions: xb = 0.005 (use 2= 1.34 for Xb = 0.005) and x = 0.02 (use λ = 0.3 for xb = 0.02). Compare the predicted ro for the two mass fraction cases. Provide a plausible reason for why the boiling heat transfer coefficient for a given AT, for one of the mass fractions is smaller than the other. 2.) A vendor wants to sell you an additive to improve the boiling heat transfer of the above R123/York-C system. The additive has a surface-tension of 0.01 N/m, a viscosity of 30 cSt, and it's a mineral oil. Should you buy it? Why? State all the reasons.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
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Chapter9: Heat Transfer With Phase Change
Section: Chapter Questions
Problem 9.28P
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Use the Kedzierski (2003) refrigerant/lubricant mixture pool boiling model to predict the boiling
heat transfer coefficient (hm) for a range of superheats (4T, = 8 K to 40 K) and Ts = 277.6 K:
5.9×107(1−x,)ph ATk, (1-e*)
x, To
Where
1₂
%₁ =
=
9m
T-T
Г
x Τσ
PL-Pbx 5.9×107(1-x₂)ph AT
0.755lp₁ (1-x₁) _ 18.75õ₁ (1—x₁) _ 18.75×10¯¹º[m]p, (1-x₂)
Xp Prv
XpPrv
XpPrv
Assume that λ = 1.34 for xb=0.005 and that λ = 0.3 for Xb = 0.02.
The properties of the refrigerant (R123) at the film temperature are:
KL
(W/mK)
0.139
R123
Or
(N/m)
179692.3 0.01764
hfg
(J/kg)
The properties of the mineral oil (lubricant) are:
PL
(kg/m³)
917.8
York-C
VL
(cSt)
60
Prv
(kg/m³)
2.701
VL
(m²/s)
6 × 10-5
OL
(N/m)
0.026
1.) Plot hm vs ATs and le vs ATs for two lubricant mass fractions: x = 0.005 (use 2 = 1.34 for
Xb = = 0.005) and x = 0.02 (use λ = 0.3 for xb = 0.02). Compare the predicted ro for the
two mass fraction cases. Provide a plausible reason for why the boiling heat transfer
coefficient for a given AT's for one of the mass fractions is smaller than the other.
2.) A vendor wants to sell you an additive to improve the boiling heat transfer of the above
R123/York-C system. The additive has a surface-tension of 0.01 N/m, a viscosity of 30
cSt, and it's a mineral oil. Should you buy it? Why? State all the reasons.
Transcribed Image Text:Use the Kedzierski (2003) refrigerant/lubricant mixture pool boiling model to predict the boiling heat transfer coefficient (hm) for a range of superheats (4T, = 8 K to 40 K) and Ts = 277.6 K: 5.9×107(1−x,)ph ATk, (1-e*) x, To Where 1₂ %₁ = = 9m T-T Г x Τσ PL-Pbx 5.9×107(1-x₂)ph AT 0.755lp₁ (1-x₁) _ 18.75õ₁ (1—x₁) _ 18.75×10¯¹º[m]p, (1-x₂) Xp Prv XpPrv XpPrv Assume that λ = 1.34 for xb=0.005 and that λ = 0.3 for Xb = 0.02. The properties of the refrigerant (R123) at the film temperature are: KL (W/mK) 0.139 R123 Or (N/m) 179692.3 0.01764 hfg (J/kg) The properties of the mineral oil (lubricant) are: PL (kg/m³) 917.8 York-C VL (cSt) 60 Prv (kg/m³) 2.701 VL (m²/s) 6 × 10-5 OL (N/m) 0.026 1.) Plot hm vs ATs and le vs ATs for two lubricant mass fractions: x = 0.005 (use 2 = 1.34 for Xb = = 0.005) and x = 0.02 (use λ = 0.3 for xb = 0.02). Compare the predicted ro for the two mass fraction cases. Provide a plausible reason for why the boiling heat transfer coefficient for a given AT's for one of the mass fractions is smaller than the other. 2.) A vendor wants to sell you an additive to improve the boiling heat transfer of the above R123/York-C system. The additive has a surface-tension of 0.01 N/m, a viscosity of 30 cSt, and it's a mineral oil. Should you buy it? Why? State all the reasons.
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