Two-phase pressure drop of ammonia in small diameter horizontal tubes

Ungar, Eugene K.; Cornwell, J. D.

doi:10.2514/6.1992-3891

Cited by 81 publications

(6 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figures 1 and 2 show the Fanning friction factor (f m ) versus Reynolds number (Re m ) in minichannels and microchannels using one of the old definitions (McAdams et al [4]) and one of the new definitions (Maxwell-Eucken II [7]) of two-phase viscosity on log-log scale. The sample of the published data includes Ungar and Cornwell's data [28] for R 717 flow at T s ≈ 74 o F (165. Table 1 presents e RMS % values based on measured Fanning friction factor and predicted Fanning friction factor using the six different definitions of two-phase viscosity for this sample of the published data.…”

Section: Resultsmentioning

confidence: 99%

“…a m s e t a l [4 ]. e R M S = 2 0 .7 6 % C hu rchill[14 ] U ng ar an d C o rnw ell[2 8] T ra n et al[29 ] C ava llini e t a l.[3 0] F ie ld a nd H rn jak [31 ] f m versus Re m in Microchannels and Minichannels Using McAdams et al [e ll-E u c ke n II[7 ] e R M S = 1 6 .4 7 % C hu rc h ill[1 4 ] U ng a r a n d C o rn w e ll[28 ] T ra n e t a l.[2 9 ] C av a llin i e t a l. [3 0] F ie ld a n d H rn ja k […”

mentioning

confidence: 99%

See 1 more Smart Citation

Two-Phase Flow Modeling in Microchannels and Minichannels

Awad

Muzychka

2008

ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels

View full text Add to dashboard Cite

In the present paper, three different methods for two-phase flow modeling in microchannels and minichannels are presented. They are effective property models for homogeneous two-phase flows, an asymptotic modeling approach for separated two-phase flow, and bounds on two-phase frictional pressure gradient. In the first method, new definitions for two-phase viscosity are proposed using a one dimensional transport analogy between thermal conductivity of porous media and viscosity in two-phase flow. These new definitions can be used to compute the two-phase frictional pressure gradient using the homogeneous modeling approach. In the second method, a simple semi-theoretical method for calculating two-phase frictional pressure gradient using asymptotic analysis is presented. Two-phase frictional pressure gradient is expressed in terms of the asymptotic single-phase frictional pressure gradients for liquid and gas flowing alone. In the final method, simple rules are developed for obtaining rational bounds for two-phase frictional pressure gradient in minichannels and microchannels. In all cases, the proposed modeling approaches are validated using the published experimental data.

show abstract

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Two-Phase Flow Modeling in Microchannels and Minichannels

Awad

Muzychka

2008

ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels

View full text Add to dashboard Cite

show abstract

“…Ungar and Cornwell [4] performed flow boiling experiments to investigate two phase pressure drop of ammonia in mini and micro channels. A range of horizontal test sections of diameter 1.46, 1.78, 2.58 and 3.15 mm respectively were used.…”

Section: Introductionmentioning

confidence: 99%

Flow boiling of ammonia in vertical small diameter tubes: Two phase frictional pressure drop results and assessment of prediction methods

Maqbool

Palm

Khodabandeh

2012

International Journal of Thermal Sciences

View full text Add to dashboard Cite

a b s t r a c tTwo phase pressure drops were measured for ammonia at a wide range of test conditions in two sizes of vertical mini channels. The test sections were made of stainless steel (AISI 316) tubes with internal diameter of 1.70 mm and 1.224 mm and a uniformly heated length of 245 mm. Experiments were conducted at three saturation temperatures of 23 C, 33 C and 43 C, the heat flux ranging from 15 to 355 kW/m 2 and the mass flux ranging from 100 to 500 kg/m 2 s. The effect of the heat flux, the mass flux, the vapour quality, the saturation temperature and the internal diameter on the two phase pressure drop are presented in this article. Some generalized two phase pressure drop correlations suggested for macro and micro scale channels are examined by comparing them with our experimental data. None of the examined correlations agreed well with the test data. A new correlation (modified form of Tran et al. correlation) is proposed which is able to predict the experimental data with MAD of 16% and 86% of the data is within AE30% range.

show abstract

“…Nevertheless many studies of microchannel flows, including this one, have found one or another of the homogeneous models to give decent predictions of pressure drop. Several studies (e.g., [3,4]) even conclude by recommending the use of homogeneous pressure drop models for microchannels based on their ease of calculation.…”

Section: Homogeneous Models For Pressure Dropmentioning

confidence: 99%