Abstract
R1234ze(Z), which has a global warming potential of less than 1, is a promising alternative refrigerant for high-temperature heat pumps designed for heat recovery in the industrial sector. The use of titanium as the material for heat exchangers exposed to acid exhaust is one solution to prevent oxidation. In this study, the pool boiling heat transfer characteristics outside of horizontal titanium tubes were experimentally investigated for R1234ze(Z). A plain tube and three enhanced titanium tubes were tested at saturation temperatures from 10°C to 60°C and heat fluxes from 0.55 to 79.8 kW m−2. Compared to the plain tube, the tested enhanced tube exhibited a 2.8 to 5.1 times higher heat transfer coefficient, on average, in the test range, which could compensate for the disadvantage in the thermal conductivity of titanium. The enhancement ratio predominantly depends on the saturation temperature and the wall heat flux. At conditions of higher saturation temperatures and lower heat flux, where smaller bubbles are observed, test tubes with smaller fin spaces exhibit higher heat transfer coefficients. The experimental results indicate the importance of fin geometry optimization to the operation conditions.
| Original language | English |
|---|---|
| Pages (from-to) | 923-932 |
| Number of pages | 10 |
| Journal | Science and Technology for the Built Environment |
| Volume | 23 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - Aug 18 2017 |
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All Science Journal Classification (ASJC) codes
- Environmental Engineering
- Building and Construction
- Fluid Flow and Transfer Processes
Cite this
Enhancement of R1234ze(Z) pool boiling heat transfer on horizontal titanium tubes for high-temperature heat pumps. / Nagata, Ryuichi; Kondou, Chieko; Koyama, Shigeru.
In: Science and Technology for the Built Environment, Vol. 23, No. 6, 18.08.2017, p. 923-932.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Enhancement of R1234ze(Z) pool boiling heat transfer on horizontal titanium tubes for high-temperature heat pumps
AU - Nagata, Ryuichi
AU - Kondou, Chieko
AU - Koyama, Shigeru
PY - 2017/8/18
Y1 - 2017/8/18
N2 - R1234ze(Z), which has a global warming potential of less than 1, is a promising alternative refrigerant for high-temperature heat pumps designed for heat recovery in the industrial sector. The use of titanium as the material for heat exchangers exposed to acid exhaust is one solution to prevent oxidation. In this study, the pool boiling heat transfer characteristics outside of horizontal titanium tubes were experimentally investigated for R1234ze(Z). A plain tube and three enhanced titanium tubes were tested at saturation temperatures from 10°C to 60°C and heat fluxes from 0.55 to 79.8 kW m−2. Compared to the plain tube, the tested enhanced tube exhibited a 2.8 to 5.1 times higher heat transfer coefficient, on average, in the test range, which could compensate for the disadvantage in the thermal conductivity of titanium. The enhancement ratio predominantly depends on the saturation temperature and the wall heat flux. At conditions of higher saturation temperatures and lower heat flux, where smaller bubbles are observed, test tubes with smaller fin spaces exhibit higher heat transfer coefficients. The experimental results indicate the importance of fin geometry optimization to the operation conditions.
AB - R1234ze(Z), which has a global warming potential of less than 1, is a promising alternative refrigerant for high-temperature heat pumps designed for heat recovery in the industrial sector. The use of titanium as the material for heat exchangers exposed to acid exhaust is one solution to prevent oxidation. In this study, the pool boiling heat transfer characteristics outside of horizontal titanium tubes were experimentally investigated for R1234ze(Z). A plain tube and three enhanced titanium tubes were tested at saturation temperatures from 10°C to 60°C and heat fluxes from 0.55 to 79.8 kW m−2. Compared to the plain tube, the tested enhanced tube exhibited a 2.8 to 5.1 times higher heat transfer coefficient, on average, in the test range, which could compensate for the disadvantage in the thermal conductivity of titanium. The enhancement ratio predominantly depends on the saturation temperature and the wall heat flux. At conditions of higher saturation temperatures and lower heat flux, where smaller bubbles are observed, test tubes with smaller fin spaces exhibit higher heat transfer coefficients. The experimental results indicate the importance of fin geometry optimization to the operation conditions.
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U2 - 10.1080/23744731.2017.1325706
DO - 10.1080/23744731.2017.1325706
M3 - Article
VL - 23
SP - 923
EP - 932
JO - Science and Technology for the Built Environment
JF - Science and Technology for the Built Environment
SN - 2374-4731
IS - 6
ER -