Comparative Analysis of Single-stage and Two-stage Fermentation Systems under Various Process Conditions

The paper analyzes electric energy consumption of three different refrigeration installations: cascade refrigeration system with R134a in the high temperature circuit and CO2 in the low temperature circuit, single stage refrigeration system operating with R404A and two-stage transcritical CO2 system. The indirect impact of the refrigeration system on global warming through electric energy consumption was examined. Thermodynamic cycles of these installations have been described and models have been developed to analyze the electric energy consumption required to drive the compressor as the largest consumer, for the cooling capacity of the evaporator 5,7 kW at evaporation temperature -30 °C for meteorological 2017, in the city of Belgrade. As a basis for comparative analysis, the existing cascade refrigeration system, which is located in the Laboratory for Thermal Science at the Faculty of Mechanical Engineering in Belgrade, was selected.

Download Full-text

The anaerobic treatment of a ligno-cellulosic substrate offering little natural pH buffering capacity

Water Science & Technology ◽

10.2166/wst.1998.0574 ◽

1998 ◽

Vol 38 (4-5) ◽

pp. 29-35 ◽

Cited By ~ 17

Author(s):

C. J. Banks ◽

P. N. Humphreys

Keyword(s):

Ph Control ◽

Anaerobic Treatment ◽

Buffering Capacity ◽

Single Stage ◽

Stable Operation ◽

Reactor Performance ◽

Two Stage ◽

Ph Buffering ◽

Stage System ◽

The Stability

The stability and operational performance of single stage digestion with and without liquor recycle and two stage digestion were assessed using a mixture of paper and wood as the digestion substrate. Attempts to maintain stable digestion in both single stage reactors were unsuccessful due to the inherently low natural buffering capacity exhibited; this resulted in a rapid souring of the reactor due to unbuffered volatile fatty acid (VFA) accumulation. The use of lime to control pH was unsatisfactory due to interference with the carbonate/bicarbonate equilibrium resulting in wide oscillations in the control parameter. The two stage system overcame the pH stability problems allowing stable operation for a period of 200 days without any requirement for pH control; this was attributed to the rapid flushing of VFA from the first stage reactor into the second stage, where efficient conversion to methane was established. Reactor performance was judged to be satisfactory with the breakdown of 53% of influent volatile solids. It was concluded that the reactor configuration of the two stage system offers the potential for the treatment of cellulosic wastes with a sub-optimal carbon to nitrogen ratio for conventional digestion.

Download Full-text

Optimization of Clean-up Process Conditions by Comparative Analysis of Dispersive Solid Phase Extraction and Automated Micro Solid Phase Extraction Clean-up for GC-MS/MS Analysis of Pesticides in Tuber Crops

Analytical Chemistry Letters ◽

10.1080/22297928.2021.1877196 ◽

2021 ◽

Vol 11 (1) ◽

pp. 29-38

Author(s):

Sarvendra Pratap Singh ◽

Jyoti Sharma

Keyword(s):

Comparative Analysis ◽

Solid Phase Extraction ◽

Solid Phase ◽

Process Conditions ◽

Phase Extraction ◽

Dispersive Solid Phase Extraction ◽

Ms Analysis ◽

Tuber Crops

Download Full-text

3D-printed gelatin methacrylate (GelMA)/silanated silica scaffold assisted by two-stage cooling system for hard tissue regeneration

Regenerative Biomaterials ◽

10.1093/rb/rbab001 ◽

2021 ◽

Vol 8 (2) ◽

Author(s):

Eunjeong Choi ◽

Dongyun Kim ◽

Donggu Kang ◽

Gi Hoon Yang ◽

Bongsu Jung ◽

...

Keyword(s):

Osteogenic Differentiation ◽

Tissue Regeneration ◽

Cooling System ◽

Composite Scaffold ◽

Human Mesenchymal Stem Cells ◽

Temperature Control System ◽

Process Conditions ◽

Hard Tissue ◽

Two Stage ◽

3D Printed

Abstract Among many biomaterials, gelatin methacrylate (GelMA), a photocurable protein, has been widely used in 3D bioprinting process owing to its excellent cellular responses, biocompatibility and biodegradability. However, GelMA still shows a low processability due to the severe temperature dependence of viscosity. To overcome this obstacle, we propose a two-stage temperature control system to effectively control the viscosity of GelMA. To optimize the process conditions, we evaluated the temperature of the cooling system (jacket and stage). Using the established system, three GelMA scaffolds were fabricated in which different concentrations (0, 3 and 10 wt%) of silanated silica particles were embedded. To evaluate the performances of the prepared scaffolds suitable for hard tissue regeneration, we analyzed the physical (viscoelasticity, surface roughness, compressive modulus and wettability) and biological (human mesenchymal stem cells growth, western blotting and osteogenic differentiation) properties. Consequently, the composite scaffold with greater silica contents (10 wt%) showed enhanced physical and biological performances including mechanical strength, cell initial attachment, cell proliferation and osteogenic differentiation compared with those of the controls. Our results indicate that the GelMA/silanated silica composite scaffold can be potentially used for hard tissue regeneration.

Download Full-text

Numerical assessment on the performance of variable area single- and two-stage ejectors: A comparative study

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1177/09544089211033129 ◽

2021 ◽

pp. 095440892110331

Author(s):

Anil Kumar ◽

Virendra Kumar ◽

PMV Subbarao ◽

Surendra K Yadav ◽

Gaurav Singhal

Keyword(s):

Change Theory ◽

Single Stage ◽

Two Stage ◽

Entrainment Ratio ◽

Ansys Fluent ◽

One Dimensional ◽

Flow Parameters ◽

Constant Rate ◽

Numerical Assessment ◽

The One

The two-stage ejector has been suggested to replace the single-stage ejector geometrical configuration better to utilize the discharge flow’s redundant momentum to induce secondary flow. In this study, the one-dimensional gas dynamic constant rate of momentum change theory has been utilized to model a two-stage ejector along with a single-stage ejector. The proposed theory has been utilized in the computation of geometry and flow parameters of both the ejectors. The commercial computational fluid dynamics tool ANSYS-Fluent 14.0 has been utilized to predict performance and visualize the flow. The performance in terms of entrainment ratio has been compared under on- design and off-design conditions. The result shows that the two-stage ejector configuration has improved (≈57%) entrainment capacity than the single-stage ejector under the on-design condition.

Download Full-text