Heat transfer by natural convection from the inside surface of a uniformly heated tube at different angles of inclination

Al-Arabi, M.; Khamis, M.; Abdulaziz, Mohamed

doi:10.1016/0017-9310(91)90013-5

Cited by 19 publications

(5 citation statements)

References 4 publications

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“…From the com par i son, it is ob vi ous that pres ent re sults lie lower than Al-Arabi et al [9] be cause of the higher Ray leigh num ber range used in his study and it was clear from the com par i son with [20] that the dif fer ent in let con fig u ra tion and length has a tremen dous ef fect on the heat trans fer re sults.…”

Section: Average Heat Transfer Correlationmentioning

confidence: 66%

“…The re sults have been com pared with the re sults of Al-Arabi et al [9] and with McAdams [20]. It was ob served that, for all in let con di tions, the Nu x in creases with the increase of heat flux, and for the same heat flux the Nu x value for bell-mouth would be higher than that for other in let con fig u ra tions and the lower value of Nu x would be occurred in L/D = 40.…”

Section: Discussionmentioning

confidence: 88%

“…All the air physical properties (r, m, n, and k) in the present work have been evaluated at the average mean film temperature T f , but all the physical properties in the previous papers which listed in references have been taken at the mean film temperature which based on ambient temperature at pipe entrance and given by T mf = = (T ms + T i ) /2 as reported by Al-Arabi et al [9]. All the air physical properties (r, m, n, and k) in the present work have been evaluated at the average mean film temperature T f , but all the physical properties in the previous papers which listed in references have been taken at the mean film temperature which based on ambient temperature at pipe entrance and given by T mf = = (T ms + T i ) /2 as reported by Al-Arabi et al [9].…”

Section: Data Analysis Methodsmentioning

confidence: 99%

“…Shigeo and Adrian [6] studied experimentally natural convection in a vertical pipe with L/D = 9 for different end temperature. Al-Arabi et al [9] investigated experimentally natural convection heat transfer from the inside surfaces of vertical tubes to air in the ranges of Gr L Pr from 1.44·10 7 to 1.02·10 10 and L/D ranged from 10 to 31.4. It was concluded that the natural convection mechanism departs considerably from the pattern known in the limit Ra ® 0.…”

Section: Introductionmentioning

confidence: 99%

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Laminar air flow free convective heat transfer inside a vertical circular pipe with different inlet configurations

Mohammed

Salman

2007

Therm sci

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Free con vec tion heat trans fer has been ex per i men tally in ves ti gated for lami nar air flow in a ver ti cal cir cu lar pipe by us ing the bound ary con di tion of con stant wall heat flux in the ranges of lo cal Rayleight num ber (Ra L ) from 1.1·10 9 to 4.7·10 9 . The ex per i men tal setup was de signed for de ter min ing the ef fect of dif fer ent con fig u ra tions placed at the in let of a ver ti cal heated pipe, on the sur face tem per a ture, the lo cal and av er age heat trans fer co ef fi cients. The ap pa ra tus was made with an elec tri cally heated alu mi num pipe with length of 900 mm and in side di am e ter 30 mm. The in let con fig u ra tions included two cir cu lar pipes hav ing the same di am e ter as the heated pipe but with lengths of 600 and 1200 mm, sharp-edge and bell-mouth. It was found that the sur face tem per a ture along the pipe sur face for same heat flux would be higher val ues for in let con di tion with length of 1200 mm and would be lower val ues for bell-mouth in let con di tion. The re sults show that the lo cal Nusselt num ber Nu x and av er age Nusselt num ber ( ) Nu L val ues would be higher for bell-mouth in let con di tion and lower val ues for 1200 mm in let con di tion. For all in let con fig u ra tions, the re sults re veal that the Nu increases as the heat flux in creases. Em pir i cal cor re la tions have been proposed in a form of log Nu L vs. log Ra L for each case in ves ti gated and a general cor re la tion for all cases has been ob tained which re veals the ef fect of in let con di tions ex is tence on the free con vec tion heat trans fer pro cess in a ver ti cal cir cu lar pipe.

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Section: Average Heat Transfer Correlationmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 88%

Section: Data Analysis Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Laminar air flow free convective heat transfer inside a vertical circular pipe with different inlet configurations

Mohammed

Salman

2007

Therm sci

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“…Davis & Perona (1971) and Kagerama & Izumi (1970). The study by Al-Arabi, Khamis & Abd-ul-Aziz (1991) shows that the inclination is an important factor to determine the flow and heat transfer of natural convection in the pipe and the heat transfer rate decreases with the increase of the inclination. The flow in the inclined pipe was also visualised by Bae, Kim & Chung (2018).…”

Section: Introductionmentioning

confidence: 99%

Effect of curvature on transient natural convection in a vertical circular pipe

Nie

2022

J. Fluid Mech.

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Natural convection adjacent to a curved vertical wall is widely present. Unfortunately, the effect of curvature on the transient thermal boundary layer (TBL) adjacent to the concave vertical wall has been neglected. In this study, dynamical evolution and thermal process of transient natural convection in a vertical circular pipe are discussed using scaling analysis, a boundary flow regime for the thin TBL without merging and a duct flow regime for the TBL with merging at the axis of the pipe are distinguished. The scaling laws quantifying the dependence of thickness, velocity and flow rate of the TBL of the fluid with the fixed Prandtl number in the vertical pipe on the Rayleigh number (RaT and Raq) and the ratio of height to radius of the pipe (A) are first reported for the isothermal and isoflux conditions. The curvature effect becomes stronger with the increase of the thickness of the TBL. Under the duct flow regime, the non-dimensional flow rate is scaled with $Ra_T^{1/2}{A^{ - 1}}$ for the isothermal condition and with $Ra_q^{1/2}{A^{ - 3/2}}$ for the isoflux condition. The scaling laws of the thickness, velocity and the flow rate of the TBL in the vertical pipe are validated based on the numerical results from direct numerical simulation (DNS) with good precision. The scaling coefficient is also presented under different regimes and conditions, which can serve as a design guide to determine natural convection in the vertical circular pipe.

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Wärmeübergang auf der Wärmeträgerseite eines Rührbehälters mit einem einfachen Mantel

Stein

Schmidt

1993

Forsch Ing-Wes

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Heat transfer by natural convection from the inside surface of a uniformly heated tube at different angles of inclination

Cited by 19 publications

References 4 publications

Laminar air flow free convective heat transfer inside a vertical circular pipe with different inlet configurations

Laminar air flow free convective heat transfer inside a vertical circular pipe with different inlet configurations

Effect of curvature on transient natural convection in a vertical circular pipe

Wärmeübergang auf der Wärmeträgerseite eines Rührbehälters mit einem einfachen Mantel

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