| 1. |
|
|
| 2. |
|
|
| 3. |
- Bobbili, Prabhakara Rao, et al.
(författare)
-
An experimental investigation of the port flow maldistribution in small and large plate package heat exchangers
- 2006
-
Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 26:16, s. 1919-1926
-
Tidskriftsartikel (refereegranskat)abstract
- An experimental investigation has been carried out to find the flow and the pressure difference across the port to channel in plate heat exchangers for a wide range of Reynolds number. 1000-17000. In the present study, low corrugation angle plates have been used for different number of channels, namely, 20 and 80. Water has been used as working fluid for both hot and cold fluids. The pressure probes are inserted through the plate gasket into both the inlet and exit ports of the channel. The pressure drop is recorded at the first, middle and last channels for each plate package of the heat exchanger. Also. the overall pressure drop has been measured for various flow rates. This overall pressure drop is a function of the flow rate, the cross-sectional area ratio of channel to port and number of channels per fluid. A simplified non-dimensional channel velocity has been suggested based on the channel pressure drop and the mean channel pressure drop of plate package, to measure the deviation of the particular channel flow rate from the mean channel flow rate. The results indicated that the flow maldistribution increases with increasing overall pressure drop in the plate heat exchangers. The experimental results are verified with M.K. Bassiouny and H. Martin's [Chemical Engineering Science 39(4) (1984) 693 and 701] analytical results. (c) 2006 Elsevier Ltd. All rights reserved.
|
|
| 4. |
- Bobbili, Prabhakara Rao, et al.
(författare)
-
Pressure Drop in Multi-Parallel Channels of Corrugated Plate Steam Condensers
- 2009
-
Ingår i: Heat Transfer Engineering. - : Informa UK Limited. - 1521-0537 .- 0145-7632. ; 30:13, s. 1024-1032
-
Konferensbidrag (refereegranskat)abstract
- An experimental investigation has been carried out to find the pressure difference of the process of steam condensation across the port to channel in plate heat exchangers. In the present study, low corrugation angle (30 degrees) plates have been used for different number of channels, namely, 10 and 80. The process steam entered at 1 bar with a small degree of superheat. Water has been used as the cold fluid. The pressure probes are inserted through the plate gasket into both the inlet and exit ports of the channel. The pressure drop of the process steam has been measured and recorded at the first, middle, and last channels at different flow and exit conditions for each plate package of the heat exchanger. Also, the overall pressure drop has been measured at different conditions at the outlet of the process steam, i.e., full and partial condensation. The pressure drop measurements have indicated that there is a considerable variation in pressure drop from the first channel to the last channel due to flow maldistribution. The experimental data has been analyzed to show how the flow maldistribution affects the pressure drop of a plate condenser.
|
|
| 5. |
- Bobbili, Prabhakara Rao, et al.
(författare)
-
Steam condensation in parallel channels of plate heat exchangers- an experimental investigation
- 2008
-
Ingår i: Heat Transfer Research. - 1064-2285. ; 39:3, s. 197-210
-
Tidskriftsartikel (refereegranskat)abstract
- An experimental investigation has been carried out to find the pressure difference of the process of steam condensation across the port to channel in plate heat exchangers. In the present study, low corrugation angle (30°) plates have been used for different number of channels, namely, 10 and 80. The process steam entered at 1 bar with a small degree of superheat. Water has been used as the cold fluid. The pressure probes are inserted through the plate gasket into both the inlet and exit ports of the channel. The pressure drop of the process steam has been measured and recorded at the first, middle, and last channels at different flow and exit conditions for each plate package of the heat exchanger. Also, the overall pressure drop has been measured at different conditions at the outlet of the process steam, i.e., full and partial condensation. The pressure drop measurements have indicated that there is a considerable variation in pressure drop from the first channel to the last channel due to flow maldistribution. The experimental data has been analyzed to show how the flow maldistribution affects the pressure drop of a plate condenser.
|
|
| 6. |
|
|
| 7. |
- Bobbili, Prabhakara Rao, et al.
(författare)
-
Thermal analysis of plate condensers in presence of flow maldistribution
- 2006
-
Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 49:25-26, s. 4966-4977
-
Tidskriftsartikel (refereegranskat)abstract
- Flow maldistribution in plate heat exchangers causes deterioration of both thermal and hydraulic performance. The situation becomes more complicated for two-phase flows during condensation where uneven distribution of the liquid to the channels reduces heat transfer due to high liquid flooding. The present study evaluates the thermal performance of falling film plate condensers with flow maldistribution from port to channel considering the heat transfer coefficient inside the channels as a function of channel flow rate. A generalized mathematical model has been developed to investigate the effect of maldistribution on the thermal performance as well as the exit quality of vapor. A wide range of parametric study is presented, which shows the effects of the mass flow rate ratio of cold fluid and two-phase fluid, flow configuration, number of channels and correlation for the heat transfer coefficient. The analysis presented here also suggests an improved method for heat transfer data analysis for plate condensers.
|
|
| 8. |
- Bobbili, Prabhakara Rao, et al.
(författare)
-
Thermal analysis of plate condensers in presence of flow maldistribution using refrigerant R134a
- 2006
-
Ingår i: Proceedings of 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006 - Process Industries. - 0791837904
-
Konferensbidrag (refereegranskat)abstract
- Flow maldistribution in plate heat exchangers causes deterioration of both thermal and hydraulic performance. The situation becomes more complicated for two phase flows during condensation where uneven distribution of the liquid to the channels reduces heat transfer due to high liquid flooding. The present study evaluates the thermal performance of falling film plate condensers with flow maldistribution from port to channel considering the heat transfer coefficient inside the channels as a function of channel flow rate. A generalized mathematical model has been developed to investigate the effect of maldistribution on the thermal performance as well as the exit vapor quality of a refrigerant, namely R-134a. A wide range of parameters are studied and these show the effects of the mass flow rate ratio of cold fluid (water) and two-phase refrigerant fluid, flow configuration, number of channels and correlation for the heat transfer coefficient. The analysis presented here also suggests an improved method for heat transfer data analysis for plate condensers. Copyright
|
|
| 9. |
- Shaji, K., et al.
(författare)
-
Logarithmic Mean Pressure Difference-A New Concept in the Analysis of the Flow Distribution in Parallel Channels of Plate Heat Exchangers
- 2012
-
Ingår i: Heat Transfer Engineering. - : Informa UK Limited. - 1521-0537 .- 0145-7632. ; 33:8, s. 669-681
-
Tidskriftsartikel (refereegranskat)abstract
- This paper deals with a new concept of logarithmic mean pressure difference (LMPD) to find an accurate mean or true friction coefficient for variable flow in parallel flow channels of the plate heat exchangers while considering the first and the last channel pressure drops. This is analogous to the log mean temperature difference (LMTD) used for the computation of heat transfer in heat exchangers. A method has been suggested to improve the computation of mean or a newly defined "true friction factor" and the mean velocity for considerable flow variations in the channels. A comparative study has been made between the conventional average friction factor and the true mean friction factor for large parallel channels. The results have also been compared between the mean channel pressure drop and LMPD for different sizes of the channels. The analysis shows that the mean channel pressure drop of parallel channels can be predicted accurately by using the so-called true mean friction factor rather than the average friction factor. Using the LMPD method, one can find the last channel pressure drop by knowing the first channel pressure drop of the plate package. Hence, the nature of flow distribution in parallel channels can be predicted easily.
|
|
