Enhanced Surface Tubing Research Articles

00/02147 Boiling characteristics of alternatives to R-502 inside air/refrigerant enhanced surface tubing

00/02147 Boiling characteristics of alternatives to R-502 inside air/refrigerant enhanced surface tubing

Experimental investigation of two phase flow condensation of alternatives to HCFC-22 inside enhanced surface tubing

This paper presents an experimental study of two phase flow condensation of some alternative zeotropic refrigerant mixtures to R-22, inside air/refrigerant horizontal enhanced surface tubing. The alternatives considered in this study are; R-507, R-404A, R-407C, and R-408A as well as R-410A. It was evident from the condensation experimental data that R-408A has the highest heat transfer rate compared to the other blends under the investigated range of refrigerant mass flow rates and heat flux. However, when the thermophysical properties are factored in, the condensation data showed that R-410A has the highest heat transfer rate at Reynolds number higher than 2.35E+7 Furthermore, experimental data of two phase condensation pressure gradient data across the test section at different Reynolds numbers showed that R-410A has the highest convective pressure drop among the blends under investigation.

Heat transfer prediction of air-to-refrigerant two-phase flow boiling of alternatives to HCFC-22 inside air/refrigerant enhanced surface tubing

In this paper, an experimental study on the heat transfer characteristics of two-phase flow boiling of some alternative refrigerants to HCFC-22, on air/refrigerant horizontal enhanced surface tubing, is presented. Correlations have been proposed to predict the heat transfer characteristics such as average heat transfer coefficients, as well as pressure drops of alternatives to R-22; such as R-507, R-404A, R-407C, R-410A and R-408A in two-phase flow boiling inside enhanced surface tubing. In addition, it was found that the refrigerant mixture's pressure drop is a weak function of the mixture's composition. It was found that the correlations were applicable to the entire heat and mass flux, investigated in the present study, for the proposed blends under question. The deviation between the experimental and predicted values for the heat transfer coefficient and pressure drop were less than ± 20, and ± 35 per cent, respectively, for the majority of data.

Heat transfer prediction of air‐to‐refrigerant two‐phase flow boiling of alternatives to HCFC‐22 inside air/refrigerant enhanced surface tubing

In this paper, an experimental study on the heat transfer characteristics of two-phase flow boiling of some alternative refrigerants to HCFC-22, on air/refrigerant horizontal enhanced surface tubing, is presented. Correlations have been proposed to predict the heat transfer characteristics such as average heat transfer coefficients, as well as pressure drops of alternatives to R-22; such as R-507, R-404A, R-407C, R-410A and R-408A in two-phase flow boiling inside enhanced surface tubing. In addition, it was found that the refrigerant mixture's pressure drop is a weak function of the mixture's composition. It was found that the correlations were applicable to the entire heat and mass flux, investigated in the present study, for the proposed blends under question. The deviation between the experimental and predicted values for the heat transfer coefficient and pressure drop were less than ±20, and ±35 per cent, respectively, for the majority of data. Copyright © 2000 John Wiley & Sons, Ltd.

Performance comparative study of new alternatives to R-502 inside air/refrigerant enhanced surface tubing

In this paper the test results of a performance evaluation of new alternatives; R-407B, R-507, R-408A and R-404A as substitutes to CFC-502 are presented. The test results were obtained using an air-source heat pump with enhanced surface tubing under standard ARI conditions. The data demonstrated that, as an interim replacement, R-408A blend has a superior performance among the proposed blends including R-502, in the range investigated. Furthermore, the alternatives to R-502 are characterised by high discharge pressure compared to R-502. In particular, R-407B and R-408A have higher discharge temperatures compared to R-502. Copyright © 2000 John Wiley & Sons, Ltd.

Two‐phase flow boiling characteristics of alternatives to R‐22 inside air/refrigerant enhanced surface tubing

Two‐phase flow boiling characteristics of alternatives to R‐22 inside air/refrigerant enhanced surface tubing

Two-phase flow boiling characteristics of alternatives to R-22 inside air/refrigerant enhanced surface tubing

In this paper, an experimental study on the heat transfer characteristics of two-phase flow boiling of alternative zeotropic refrigerant mixtures to R-22, on air/refrigerant horizontal enhanced surface tubing is presented. The new alternatives considered in this study are: R-507, R-404A, R-408A, R-407C, and R-410A. The experimental data showed that R-22 has the highest heat transfer rate compared to the other blends in the range investigated. Furthermore, it was also quite evident from these data that R-410A has the highest pressure among the blends under investigation for Reynolds number greater than 3.5×104. However, for Reynolds number less than 3.6×104, it appears from the data that R-22 has the highest pressure drop compared to other refrigerants under investigation. Copyright © 2000 John Wiley & Sons, Ltd.

Prediction of convective boiling characteristics of alternatives to R-502 inside air/refrigerant enhanced surface tubing

In this paper, an experimental study on the heat transfer characteristics of two-phase flow boiling of alternative azeotropic refrigerant mixtures to R-502 on air/refrigerant horizontal enhanced surface tubing is presented. Correlations were proposed to predict the heat transfer characteristics such as average heat transfer coefficients, as well as pressure drops of alternatives to R-502; such as R-507, R-404A, R-407B, and R-408A in two-phase flow boiling inside enhanced surface tubing. In addition, it was found that the refrigerant mixture’s pressure drop is a weak function of the mixture’s composition. It was found that the correlations were applicable to the entire heat and mass flux, investigated in the present study for the proposed blends under question. The deviation between the experimental and predicted values for the heat transfer coefficient and pressure drop were less than ±20% and 35%, respectively, for the majority of data.

Prediction of two-phase condensation characteristics of some alternatives to R-22 inside air/refrigerant enhanced surface tubing

The results of an experimental study on the heat transfer characteristics of two-phase flow condensation of some azeotropic refrigerant mixtures, proposed as alternatives to R-22, on air/refrigerant horizontal enhanced surface tubing are presented. The condensation data indicated that the heat transfer coefficient of the blend R-408A has the highest heat transfer rate among the blends under investigation. The condensation data also showed that R-507 and R-404A have similar heat transfer rates to that of R-22 when plotted against the refrigerant mass flow rate. It can also be observed that, as the mass flux increases, the heat transfer coefficient increases. Correlations were proposed to predict the heat transfer characteristics such as average heat transfer coefficients as well as pressure drops of alternatives to R-22 such as R-507, R-404A, R-407C and R-408A, as well as R-410A in two-phase flow condensation inside enhanced surface tubing. In addition, proposed correlations were found to fairly predict the two-phase flow heat transfer condensation data. Copyright © 2000 John Wiley & Sons, Ltd.

Performance analysis of new alternatives to HCFC-22 inside air/refrigerant-enhanced surface tubing

In this paper, the test results of a performance analysis of new alternatives; R-410A, R-507, R-407C, R-408A and R-404A proposed as substitutes to HCFC-22 are presented. The test results were obtained using an air-source heat pump with enhanced surface tubing. Performance tests were conducted according to the ARI/ASHRAE Standards. The performance data demonstrated that as an interim replacement, the R-404A blend has a superior performance particularly at low temperatures among the proposed blends. Furthermore, the alternatives to R-22 are characterised by high discharge pressure compared to that of R-22. In particular, R-410A has the highest discharge pressure among the blend studied. R-407C has similar discharge temperature to R-22 at temperatures lower than - 8°C.

Boiling characteristics of alternatives to R-502 inside air/refrigerant enhanced surface tubing

In this paper, an experimental study on the heat transfer characteristics of two-phase flow boiling of alternative zeotropic refrigerant mixtures to R-502, on air/refrigerant horizontal enhanced surface tubing is presented. The new alternatives considered in this study are: R-507, R-404A, R-407B, and R-408A. It was evident from the experimental data that R-502 has the lowest heat transfer rate compared to the other blends in the range investigated. Furthermore, it was also quite evident from these data that R-407B has the highest pressure among the blends under investigation. However, at a Reynolds number less than 3.6×104, it appears from the data that R-404A has the lowest pressure drop compared to other refrigerants under investigation. Copyright © 2000 John Wiley & Sons, Ltd.

Boiling characteristics of alternatives to R‐502 inside air/refrigerant enhanced surface tubing

In this paper, an experimental study on the heat transfer characteristics of two-phase flow boiling of alternative zeotropic refrigerant mixtures to R-502, on air/refrigerant horizontal enhanced surface tubing is presented. The new alternatives considered in this study are: R-507, R-404A, R-407B, and R-408A. It was evident from the experimental data that R-502 has the lowest heat transfer rate compared to the other blends in the range investigated. Furthermore, it was also quite evident from these data that R-407B has the highest pressure among the blends under investigation. However, at a Reynolds number less than 3.6×104, it appears from the data that R-404A has the lowest pressure drop compared to other refrigerants under investigation. Copyright © 2000 John Wiley & Sons, Ltd.

Prediction of condensation characteristics of alternatives to R-502 inside air–refrigerant enhanced surface tubing

In this paper, an experimental study on the heat transfer characteristics of two-phase flow condensation of alternative azeotropic refrigerant mixtures to R-502, on air/refrigerant horizontal enhanced surface tubing, is presented. The condensation data indicated that the heat transfer coefficient on the blend R-408A has the highest heat transfer rate among the blends under investigation. The condensation data also showed that R-502 and R-407B have similar heat transfer rates when plotted against the refrigerant mass flow rate. It also can be observed that, as the mass flux increases, heat transfer coefficient increases. Correlations were proposed to predict the heat transfer characteristics such as average heat transfer coefficients, as well as pressure drops of alternatives to R-502; such as R507, R404A, R407B and R408A in two-phase flow condensation inside enhanced surface tubing. In addition, proposed correlations were found to fairly predict the two-phase flow heat transfer condensation data.

Two phase flow heat transfer of binary mixtures inside enhanced surface tubing

The primary heat transfer parameters such as coefficient of heat transfer and pressure drop observed during condensation of binary azeotropic refrigerant mixtures R-410a (R125/R32: 50/50), and R-507 (R125/R143a: 50/50) are presented in this paper. Experiments showed that for Reynolds numbers higher than 4.2 E06, R-410a appears to have greater heat transfer rates more than the other blends under investigation. Furthermore, it is quite evident from this data that R-507 has the highest pressure drop among the refrigerants under investigation.

98/00667 Flow boiling and condensation of tetrary refrigerant mixtures inside water/refrigerant enhanced surface tubing

98/00667 Flow boiling and condensation of tetrary refrigerant mixtures inside water/refrigerant enhanced surface tubing

Flow boiling and condensation of tetrary refrigerant mixtures inside water/refrigerant enhanced surface tubing

This work presents the results of an experimental study concerning the heat transfer characteristics of two-phase flow condensation and boiling of tetrary (R-32/R-125/R143a/R134a) refrigerant mixtures inside water/refrigerant horizontal enhanced surface tubing. Heat transfer characteristics such as average heat transfer coefficients, as well as pressure drops of the tetrary refrigerant mixtures, have been predicted and compared with other mixtures during flow condensation and boiling inside enhanced surface tubing. It was found that the tetrary refrigerant blend has higher transfer coefficients than R-502, and the lowest pressure drop among the refrigerants studied. © 1997 by John Wiley & Sons, Ltd.

97/05007 Flow boiling and condensation of tetrary refrigerant mixtures inside water/refrigerant enhanced surface tubing: Sami, S. M. and Song, B. Int. J. Energy Res., 1997, 21, (14), 1305–1320

97/05007 Flow boiling and condensation of tetrary refrigerant mixtures inside water/refrigerant enhanced surface tubing: Sami, S. M. and Song, B. Int. J. Energy Res., 1997, 21, (14), 1305–1320

Heat transfer and pressure drop characteristics of HFC quaternary refrigerant mixtures inside horizontal enhanced surface tubing

Heat transfer characteristics of two-phase flow condensation and boiling of quaternary (four components) refrigerant mixtures, on air/refrigerant horizontal enhanced surface tubing are presented, discussed and compared to other refrigerants proposed as substitutes for CFC-502, such as R-507 and R-407B. Heat transfer characteristics, such as average heat transfer coefficients, as well as pressure drops of ternary azeotropic refrigerant mixtures, flow condensation and boiling inside enhanced surface tubing, were predicted. Experimental data showed that our proposed quaternary blend has a superior boiling heat transfer coefficient and higher pressure drop compared to CFC-502.

95/01912 Forces convective condensation and boiling of ternary non-azeotropic refrigerant mixtures inside water/refrigerant enhanced surface tubing

95/01912 Forces convective condensation and boiling of ternary non-azeotropic refrigerant mixtures inside water/refrigerant enhanced surface tubing

95-01928 Prediction of the condensation and boiling characteristics of R12 substitutes R22/R152a/R114 and R22/R152a/R124 Inside enhanced-surface tubing

95-01928 Prediction of the condensation and boiling characteristics of R12 substitutes R22/R152a/R114 and R22/R152a/R124 Inside enhanced-surface tubing