Numerical Simulation of Heat and Moisture Transfer in Corrugated Walls Dryer
Balbine Matuam,
Nicolas Gnepie,
Jaures Fotsa,
Abraham Tetang,
Marcel Edoun,
Et Alexis Kuitche
Issue:
Volume 7, Issue 1, June 2023
Pages:
1-10
Received:
27 January 2023
Accepted:
17 February 2023
Published:
28 February 2023
Abstract: The primary goal of the current work is to model heat and mass transfer during mango drying in a wavy airflow dryer. By modifying the dryer walls, we were able to produce the undulating airflow (with V-shaped obstacles). With convective boundary conditions applied to all product surfaces, the explicit finite difference approach was used to study heat and mass exchanges in two dimensions during the drying of mango slices. During drying, the transfer coefficients are thought to fluctuate. Using EasyCFD software, the external flow, temperature, velocity, and pressure fields were then analyzed. This provided the profile of the heat transfer coefficient. These profiles were then utilized to calculate the mass transfer coefficient using the Shilton-Colburn analogy. Moreover, the code created to determine the heat and mass transfer coefficients in the product was used to derive the evolution of temperature and moisture content over time. The results allowed for the discovery of a new air flow in dryers called an undular flow and demonstrated how modifying the drying air stream enhanced heat transfer efficiency. By changing the air flow in the dryer, it was possible to achieve heat transfer coefficients ranging from 47.55 W/m2K to 357.38 W/m2K and mass transfer coefficients of 3.21 x 10-5 to 3.21 x 10-4 m2/s. When the outcomes of this investigation were compared to experimental results from the literature (under identical drying circumstances), a reasonable level of adequacy was discovered.
Abstract: The primary goal of the current work is to model heat and mass transfer during mango drying in a wavy airflow dryer. By modifying the dryer walls, we were able to produce the undulating airflow (with V-shaped obstacles). With convective boundary conditions applied to all product surfaces, the explicit finite difference approach was used to study he...
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Effects of Upstream Flow Disturbances on Elbow Meter Performance
Riley Manwaring,
Michael Johnson,
Zachary Sharp,
Steven Barfuss
Issue:
Volume 7, Issue 1, June 2023
Pages:
11-18
Received:
19 February 2023
Accepted:
13 March 2023
Published:
24 March 2023
Abstract: In order to fill gaps in research into the use of elbow flow meters and to reconcile both a lack of published standards and differing recommendations on the necessary minimum lengths of straight pipe that should be installed upstream of an elbow flow meter to ensure sufficiently accurate flow measurement, physical data were collected on 50 mm nominal (52.5 mm or 2.067 inch actual), 150 mm nominal (154.05 mm or 6.065 inch actual), and 305 mm nominal (304.8 mm or 12.00 inch actual) long-radius elbow meters to determine discharge coefficients in a straight-line pipeline configuration. The 150 mm (6-inch) long-radius elbow meter was further tested in order to determine the effects of different upstream disturbances on the accuracy of its metering performance. Three different upstream disturbances were tested at upstream distances of 25, 10, and 5 diameter-lengths, including: a single elbow in-plane “S” orientation, a single elbow in-plane “U” orientation, and a double elbows out-of-plane orientation. Discharge coefficients were calculated for each configuration at the three variable upstream distances between the upstream flow disturbance and the meter and compared to the straight-line calibration values to identify the percent difference shifts in the average discharge coefficients. Most importantly, findings from the present study conclude that the discharge coefficients for all elbow meter installations stabilize for pipe Reynolds numbers greater than 300,000. Additionally, even at upstream distances of 25 pipe diameter lengths (3.81 m or 12.5 feet) each of the three upstream flow disturbances continued to exhibit effects on the calculated discharge coefficients for the elbow meter; the observed difference in the average discharge coefficient for the two single elbow in-plane configurations “S” and “U” were within 1.00% of the straight-line values. Finally, the double elbows out-of-plane discharge coefficient values remained constant, regardless of the three tested distances between 5 and 25 diameter lengths between the elbow meter and the upstream flow disturbance, showing a more predictable shift in discharge coefficient than the two single elbow in-plane configurations.
Abstract: In order to fill gaps in research into the use of elbow flow meters and to reconcile both a lack of published standards and differing recommendations on the necessary minimum lengths of straight pipe that should be installed upstream of an elbow flow meter to ensure sufficiently accurate flow measurement, physical data were collected on 50 mm nomin...
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Fabrication and Performance Assessment of Desulfurizing Systems for Large-Scale Biodigesters in Cambodia
Lyhour Hin,
Lytour Lor,
Dyna Theng,
Chan Makara Mean,
Sovanndy Yut,
Mengchhay Kim,
Sokhom Mech,
Gerald Hitzler
Issue:
Volume 7, Issue 1, June 2023
Pages:
19-26
Received:
31 May 2023
Accepted:
25 June 2023
Published:
6 July 2023
Abstract: Commercial pig farms in Cambodia produce great amounts of wastewater. To convert wastewater into energy, many farms have installed simple covered lagoon digesters. However, most biodigesters lack desulfurizing systems to reduce H2S present in biogas for smooth generator operation. Desulfurizing systems are not available locally and must be imported from abroad. They are expensive, while after-sale service is hard to find. These factors may lead reluctancy to fully invest in biogas systems. Therefore, this paper aimed to compare biogas quantity and quality between two desulfurizing systems, to analyze electricity generation and generator efficiency, and to perform economic assessment of the desulfurizing systems. The study was conducted on two large-scale pig farms in two different periods. The first period was with a pig farm of 20,000 fattening pigs and 6,000 sows in Preah Sihanoukville Province, from October 2021 to July 2022. The second period targeted a pig farm of 5,000 fattening pigs and 600 sows in Kampong Thom Province between May 2022 and May 2023. The results show that biogas quantity was greater with the first farm because it had more pigs. CH4, CO2, and O2 were not different before and after desulfurization for each desulfurizing system. CH4 measured on the farm that used the Chinese desulfurizing system was 52.1%, much lower than the farm with the BTIC desulfurizing system (62.9% CH4) due to high O2 concentration inside the biogas pipe. H2S was affected by desulfurization and reduced to lower than 100 ppm, which is good for generator operation. Due to larger generator size, the first farm produced greater output power (276 kW), when compared to the second farm that had output power of 125 kW. Higher generator efficiency was also observed on the first farm, but loading rate was similar for both farms. Depreciation costs for the Chinese desulfurizing system were 3,375 USD/year, being 4.3 times higher than those of the BTIC prototype (787.5 USD/year). The size and capacity of the BTIC desulfurizing system is similar to the Chinese product. Thus, if the first farm used the BTIC prototype, huge amounts of money could be saved annually. In conclusion, the BTIC desulfurizing system had a working performance similar to that of the Chinese product, but had low depreciation costs, denoting huge savings. Further studies should focus on the dissemination of the BTIC prototype to more pig farms through collaboration with the private sector and fabricators for strong market linkage.
Abstract: Commercial pig farms in Cambodia produce great amounts of wastewater. To convert wastewater into energy, many farms have installed simple covered lagoon digesters. However, most biodigesters lack desulfurizing systems to reduce H2S present in biogas for smooth generator operation. Desulfurizing systems are not available locally and must be imported...
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