scholarly journals Molded Vial Manufacturing and Its Impact on Heat Transfer during Freeze-Drying: Vial Geometry Considerations

2021 ◽  
Vol 22 (2) ◽  
Author(s):  
Tim Wenzel ◽  
Henning Gieseler
Keyword(s):  
Heat Transfer ◽  
Contact Area ◽  
Freeze Drying ◽  
Thermal Characteristics ◽  
Heat Transfer Characteristics ◽  
Transfer Parameter ◽  
Manufacturing Technique ◽  
Transfer Characteristics ◽  
Heat Transfer Parameter ◽  
Glass Compositions

AbstractRecent advances in molded vial manufacturing enabled manufacturers to use a new manufacturing technique to achieve superior homogeneity of the vial wall thickness. This study evaluated the influence of the different manufacturing techniques of molded vials and glass compositions on vial heat transfer in freeze-drying. Additionally, the influence of using empty vials as thermal shielding on thermal characteristics of edge and center vials was investigated. The vial heat transfer coefficient Kv was determined gravimetrically for multiple vial systems. The results showed superior heat transfer characteristics of the novel manufacturing technique as well as differences in heat transfer for the different glass compositions. Empty vials on the outside of the array did not influence center vial Kv values compared to a full array. The direct contact area and vial bottom curvature and their correlation to heat transfer parameters were analyzed across multiple vial systems. A new approach based on light microscopy to describe the vial bottom curvature more accurately was described. The presented results for the contact area allowed for an approximation of the pressure-independent heat transfer parameter KC. The results for the vial bottom curvature showed a great correlation to the pressure-dependent heat transfer parameter KD. Overall, the results highlighted how a thorough geometrical characterization of vials with known heat transfer characteristics could be used to predict thermal characteristics of new vial systems as an alternative to a time-consuming gravimetric Kv determination. Primary drying times were simulated to show the influence of Kv on drying performance.

Flow and Thermal Characteristics Analysis of Plate–Finned Tube and Annular–Finned Tube Heat Exchangers fo In–Line and Staggered Configurations

2020 ◽  
Vol 22 (4) ◽  
pp. 1407-1418
Author(s):  
Shadman Sakib ◽  
Abdullah Al-Faruk
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Air Flow ◽  
Thermal Characteristics ◽  
Finned Tube ◽  
Air Flow Rate ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Exit Temperature

AbstractAs the effective selection of fin can greatly enhance the performance of heat exchanger, heat transfer and pressure drop performance on the air-side of annular and rectangular finned tube heat exchangers were numerically investigated. Two types of tube arrangement (in-line and staggered alignment) were examined for 6 different air flow rate for both the heat exchangers using computational fluid dynamics software package ANSYS FLUENT. Renormalization group theory (RNG) based k-ε turbulence model was employed to handle the unsteady three-dimensional flow and the conjugate heat transfer characteristics. The exit temperature were determined from the simulated results and then the LMTD, heat transfer rate and air-side heat transfer coefficient were calculated. The numerical flow visualization results revealed few important aspects, such as, the development boundary layers between the fins, the formation of the horseshoe vortex system, and the local variations of the velocity and temperature on the fin geometries. The result shows that as the air flow rate increased the exit temperature decreased but the overall heat transfer increased. Staggered configuration shows higher heat transfer characteristics over the in-line configuration. The rectangular finned tube shows 17 to 24% improvement in heat transfer over the annular finned tube.

scholarly journals KARAKTERISTIK PERPINDAHAN PANAS KONVEKSI ALAMIAH ALIRAN NANOFLUIDA AL2O3-AIR DI DALAM PIPA ANULUS VERTIKAL

2016 ◽  
Vol 18 (1) ◽  
pp. 21
Author(s):  
Reinaldy Nazar
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Power Plants ◽  
Convection Heat Transfer ◽  
Thermal Characteristics ◽  
Heat Transfer Fluid ◽  
Empirical Correlations ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Vertical Annulus

ABSTRAK KARAKTERISTIK PERPINDAHAN PANAS KONVEKSI ALAMIAH ALIRAN NANOFLUIDA AL2O3-AIR DI DALAM PIPA ANULUS VERTIKAL. Hasil beberapa penelitian menunjukan bahwa nanofluida memiliki karakteristik termal yang lebih baik dibandingkan dengan fluida konvensional (air). Berkaitan dengan hal tersebut, saat ini sedang berkembang pemikiran untuk menggunakan nanofluida sebagai fluida perpindahan panas alternatif pada sistem pedingin reaktor. Sementara itu, konveksi alamiah di dalam pipa anulus vertikal merupakan salah satu mekanisme perpindahan panas yang penting dan banyak ditemukan pada reaktor riset TRIGA, reaktor daya generasi baru dan alat konversi energi lainnya. Namun disisi lain karakteristik perpindahan panas nanofluida di dalam pipa anulus vertikal belum banyak diketahui. Oleh karena itu penting dilakukan secara berkesinambungan penelitian-penelitian untuk menganalisis perpindahan panas nanofluida di dalam pipa anulus vertikal. Pada penelitian telah dilakukan analisis numerik menggunakan program computer CFD (computational of fluids dynamic) terhadap karakteristik perpindahan panas konveksi alamiah aliran nanofluida Al2O3-air konsentrasi 2% volume di dalam pipa anulus vertikal. Hasil kajian ini menunjukkan terjadi peningkatan kinerja perpindahan panas (bilangan Nuselt- NU) sebesar 20,5% - 35%. Pada moda konveksi alamiah dengan bilangan 2,4708e+09 £ Ra £ 1,9554e+13 diperoleh korelasi empirik untuk air adalah dan korelasi empirik untuk nanofluida Al2O3-air adalah   Kata kunci: Nanofluida Al2O3-air, konveksi alamiah, pipa anulus vertikal     ABSTRACT THE CHARACTERISTICS OF NATURAL CONVECTIVE HEAT TRANSFER OF AL2O3–WATER NANOFLUIDS FLOW IN A VERTICAL ANNULUS PIPE. Results of several research have shown that nanofluids have better thermal characteristics compared to conventional fluid (water). In this regard, currently developing ideas for using nanofluids as an alternative heat transfer fluid in the reactor coolant system. Meanwhile the natural convection in a vertical annulus pipe is one of the important mechanisms of heat transfer and is found at the TRIGA research reactor, the new generation nuclear power plants and other energy conversion devices. On the other hand the heat transfer characteristics of nanofluids in a vertical annulus pipe has not been known. Therefore, it is important to do research continuously to analyze the heat transfer nanofluids in a vertical annulus pipe. In the research has been carried out numerical analysis by using computer code of CFD (computational of fluids dynamic) on natural convection heat transfer characteristics of nanofluids flow of Al2O3-water 2% volume in the vertical annulus pipe. The results showed an increase in heat transfer performance (Nusselt numbers - NU) by 20.5% - 35%. In natural convection mode with Rayleigh numbers 2.4708e+09 £ Ra £ 1.9554e+13 obtained empirical correlations for water is and empirical correlations for Al2O3-water nanofluids is .   Keywords: Al2O3-water nanofluids, the natural convection, the vertical annulus pipe

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