| 1. |
- Al-Obaidi, Mudhar A., et al.
(författare)
-
Optimizing Reverse Osmosis Feed Spacer Design for Enhanced Dimethylphenol Removal from Wastewater: A Study of Hydrodynamics and Performance Indicators
- 2024
-
Ingår i: Water. - : MDPI. - 2073-4441. ; 16:6
-
Tidskriftsartikel (refereegranskat)abstract
- Due to its high pollutant rejection and low energy usage, the spiral wound module of reverse osmosis (RO) process is the most commonly used technology utilised in wastewater treatment. For a spiral wound module, the presence of a feed spacer is important as a key solution to mitigate the concentration polarisation phenomenon, due to disorderly fluid flow, and to improve the mass transfer coefficient. Undoubtedly, improvements in the spiral wound module design, mainly in the symmetrical shape of the feed spacer, can have a significant impact on the cost and probable use of these modules. Despite the wide interest in appraising the impact of feed spacer geometry and orientation on the performance of a spiral wound module for RO process-based water desalination, the hydrodynamics of feed spacers (pressure drop and mass transfer coefficient) and the associated influences of feed spacer design (the height of the feed spacer, the angle of the filaments, and the porosity) on the removal of pollutants from wastewater have not yet been addressed. The current investigation aims to fill this gap by studying the hydrodynamics and design parameters of the selected parallelogram feed spacer type ultrafiltration (UF−3) for the removal of dimethylphenol from wastewater. Using model-based simulation, the impacts of UF−3 feed spacer design parameters, including the height, angle between the filaments (orientation), and porosity on the pressure drop, friction factor, axial flow fluid velocity, mass transfer coefficient, water flux, dimethylphenol rejection, recovery rate, and specific energy consumption are detailed in this study. The study intends to demonstrate the optimum design features of UF−3 feed spacer that should be considered to assure the highest elimination of dimethylphenol from wastewater in addition to the lowest specific energy consumption.
|
|
| 2. |
- Ameen, Arman, 1976-, et al.
(författare)
-
Assessment of Thermal Comfort and Air Quality in Office Rooms of a Historic Building: A Case Study in Springtime in Continental Climate
- 2023
-
Ingår i: Buildings. - : MDPI. - 2075-5309. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- One of the most important aspects of working in an office environment is ensuring that the space has optimal thermal comfort and an indoor environment. The aim of this research is to investigate the thermal comfort and indoor climate in three office rooms located at one of the campus buildings at the University of Gävle, Sweden. The evaluated period is in the month of April during springtime. During this period, parameters such as temperature, relative humidity, CO2, supply air flow rate, and room air velocities are measured on site. The results of the measurement show that the indoor temperature is on average lower in the rooms facing north, at 21–23.5 °C, compared to the rooms facing south, which reach high temperatures during sunny days, up to 26 °C. The results also show that the ventilation air supply rate is lower than the requirement for offices in two of the office rooms. The ACH rate is also low, at ≈ 1 h−1 for all the rooms, compared to the required levels of 2–4 h−1. The CO2 levels are within the recommended values; on average, the highest is in one of the south-facing rooms, with 768 ppm, and the maximum measured value is also in the same room, with 1273 ppm for a short period of time.
|
|
| 3. |
- Ameen, Arman, 1976-, et al.
(författare)
-
Assessment of Thermal Comfort and Indoor Air Quality in Library Group Study Rooms
- 2023
-
Ingår i: Buildings. - : MDPI. - 2075-5309. ; 13:5
-
Tidskriftsartikel (refereegranskat)abstract
- Human performance and health are among the most relevant topics in the modern society, especially at young ages, when academic performance is indispensable. Thus, as humans spend most of their lifetime inside a building, thermal comfort and indoor air quality are an essential aspect of a room. The aim of the current study is to numerically evaluate the main thermal comfort parameters such as PMV and PPD as well as indoor air quality, i.e., CO2 concentration, in library group study rooms at the University of Gävle in Sweden. Rotroninc Measurement Solutions CL11 sensors were utilized for temperature measurements. Simulation models were created and validated based of building data as well as temperature measurements. Several simulations were conducted throughout a year, covering different periods. The results show that even though the ventilation system, with only temperature control, works as intended for maintaining the thermal comfort, the CO2 concentration rises above 1000 ppm when more than one student occupy the rooms, which is not recommended by different thermal comfort ruling institutions. Consequently, a modification to the ventilation system control is recommended, changing it from temperature control to CO2 and temperature control.
|
|
| 4. |
- Ameen, Arman, 1976-, et al.
(författare)
-
Energy Performance Evaluation of Historical Building
- 2022
-
Ingår i: Buildings. - : MDPI. - 2075-5309. ; 12:10
-
Tidskriftsartikel (refereegranskat)abstract
- Retrofitting measures in old buildings aimed at reducing energy usage have become important procedures meant to counteract the effects of climate change and greenhouse gas emissions. The aim of this study is to evaluate energy usage, thermal comfort, and CO2 emissions of an old building by changing parameters such as building orientation, shading systems, location, low energy film application, and alternative energy supply in the form of a geothermal heat pump. When evaluating the buildings in terms of geographical location with or without applying the low energy film, the results show that the city of Gävle in Sweden requires the most heating energy, 150.3 kWh/m2∙year (B0) compared to Jakarta (L0), which requires 23.8 kWh/m2∙year. When examining the thermal comfort, cases B4 and L4 demonstrate the best results in their respective categories (B0–B4 are cases without low energy film and L0–L4 are cases with applied low energy film). The results for the CO2 emissions levels for B0–B4 and L0–L4 indicate that B4 has the highest value, 400 kg CO2 eq/year higher than B0, and L1 has the lowest value, 731 kg CO2 eq/year lower than B0. The economic feasibility study illustrates that the installation of a geothermal heat pump with at least a coefficient of performance of 4.0 leads to a shorter payback period than solely applying LEF.
|
|
| 5. |
- Ameen, Arman, 1976-, et al.
(författare)
-
Energy saving, indoor thermal comfort and indoor air quality evaluation of an office environment using corner impinging jet ventilation
- 2023
-
Ingår i: Developments in the Built Environment. - : Elsevier. - 2666-1659. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of a corner based impinging jet ventilation system (CIJV) in an office environment was evaluated numerically. The evaluation was done both in terms of the local thermal comfort and the local indoor air quality. Three different inlet configurations were tested for a range of outdoor temperatures that included both winter and summer conditions. In terms of indoor air quality, the results showed that CIJV performed better than a traditional mixing system. The study also revealed that CIJV creates a stronger temperature stratification in summertime compared to wintertime. When evaluating the energy saving potential the results showed a possible reduction of 7% for the ventilation flowrate when the outdoor temperatures were between -15 °C and -5 °C, 8 % when the outdoor temperatures were between 0 °C and 10 °C and 9 % when the outdoor temperatures were between 15 °C and 25 °C.
|
|
| 6. |
- Ameen, Arman, 1976-
(författare)
-
Experimental and numerical study of corner impinging jet ventilation for an office environment
- 2024
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An effective ventilation system is an important component of a building’s service infrastructure. It serves the dual purpose of creating a comfortable and healthy indoor environment for occupants, thereby enhancing their well-being and productivity. However, the ventilation system is also a part of the building that uses a high amount of energy.The main objective of this study is to evaluate a novel implementation of the impinging jet ventilation system by placing the supply inlet at the corners of the space or room, rather than in the traditional mid-wall section. The focus of this study is to test and evaluate corner impinging jet ventilation in a medium-sized office environment within a building that requires moderate amount of heating and cooling.In the first part of this study (summer condition), the system is evaluated in an experimental environment, where it is compared against other systems such as displacement ventilation and mixing ventilation. The evaluated parameters indicates that corner impinging ventilation system performs better than mixing ventilation but show similar results to displacement ventilation in terms of airchange effectiveness. This experimental setup was also tested in winter condition and the results showed that the system was most effective during summertime compared to wintertime. In wintertime the results for the air change effectiveness were similar to those of a mixing system.In the second part, numerical simulations were utilized to delve deeper into the behaviour of the corner impinging jet ventilation system close to the floor surface. A numerical model was created and validated against experimental measurements. In this part, the spreading of the air jet across the room floor was examined, and its relation to various parameters such as inlet velocity, inlet shape and discharge height. Results indicated that diffuser geometries have almost no impact on velocity profile along the floor's centreline, jet spreading rate and maximum velocity decay. The results also showed a high degree of flexibility for the room size, between 25-100 m2 for which the results were applicable. The results also concluded that there was a noticeable confinement effect present and that the jet was able to travel far into the room.In the third part numerical simulations was used for validating and to create a model for an office room containing two office workstations. The office room was evaluated in terms of local thermal comfort, close to the sitting area. In addition, the indoor air quality was also examined. The results showed that corner impinging ventilation system performed better than conventional mixing ventilation system, especially when evaluating the indoor air quality in terms of mean age of air. This evaluation also took into account both outdoor summer and winter conditions, as well as different inlet surface areas. Different locations for the workstations were also evaluated with good results, except for placing the work-stations close to the inlets. Due to the system’s effectiveness of providing fresh air to the occupants, further analysis was made to try and reduce the air flowrate but keep the same indoor air quality level as an equivalent fully mixing ventilation system. By using this method, the study was able to demonstrate reduction in the energy use by reducing the air flowrate of the supply inlet. The study showed a possible reduction of the energy use by 7-9 % for outdoor temperatures ranging between -15 °C to 25 °C.
|
|
| 7. |
- Ameen, Arman, 1976-, et al.
(författare)
-
Experimental Evaluation of the Ventilation Effectiveness of Corner Stratum Ventilation in an Office Environment
- 2019
-
Ingår i: Buildings. - : MDPI. - 2075-5309. ; 9:7
-
Tidskriftsartikel (refereegranskat)abstract
- An experimental study was conducted in a room resembling an office in a laboratory environment. The study involved investigating the ability of corner-placed stratum ventilation in order to evaluate the ventilation’s effectiveness and local thermal comfort. At fixed positions, the air temperature, air velocity, turbulence intensity, and tracer gas decay measurements were carried out. The results show that corner-placed stratum ventilation behaves very similar to a mixing ventilation system when considering air change effectiveness. The performance of the system was better at lower supply air flow rates for heat removal effectiveness. For the heating cases, the draught rates were all very low, with the maximum measured value of 12%. However, for the cooling cases, the maximum draught rate was 20% and occurred at ankle level in the middle of the room.
|
|
| 8. |
- Ameen, Arman, 1976-, et al.
(författare)
-
Experimental Investigation of Ventilation Performance of Different Air Distribution Systems in an Office Environment : Heating Mode
- 2019
-
Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 12:10
-
Tidskriftsartikel (refereegranskat)abstract
- A vital requirement for all-air ventilation systems are their functionality to operate both in cooling and heating mode. This article experimentally investigates two newly designed air distribution systems, corner impinging jet (CIJV) and hybrid displacement ventilation (HDV) in comparison against a mixing type air distribution system. These three different systems are examined and compared to one another to evaluate their performance based on local thermal comfort and ventilation effectiveness when operating in heating mode. The evaluated test room is an office environment with two workstations. One of the office walls, which has three windows, faces a cold climate chamber. The results show that CIJV and HDV perform similar to a mixing ventilation in terms of ventilation effectiveness close to the workstations. As for local thermal comfort evaluation, the results show a small advantage for CIJV in the occupied zone. Comparing C2-CIJV to C2-CMV the average draught rate (DR) in the occupied zone is 0.3% for C2-CIJV and 5.3% for C2-CMV with the highest difference reaching as high as 10% at the height of 1.7 m. The results indicate that these systems can perform as well as mixing ventilation when used in offices that require moderate heating. The results also show that downdraught from the windows greatly impacts on the overall airflow and temperature pattern in the room.
|
|
| 9. |
- Ameen, Arman, 1976-, et al.
(författare)
-
Numerical Evaluation of the Flow Field of An Isothermal Dual-Corner Impinging Jet for Building Ventilation
- 2022
-
Ingår i: Buildings. - : MDPI. - 2075-5309. ; 12:10
-
Tidskriftsartikel (refereegranskat)abstract
- The corner impinging jet ventilation is a new air distribution system for use in office environments. This study reports the mean flow field behavior of dual isothermal corner-placed inlets based on an impinging jet in a square-shaped room with the size of 7.2 m × 7.2 m. A detailed numerical study is carried out to evaluate the influence the different configuration parameters, such as the inlet placement, same side or opposite side, and supply airflow rate, have on the flow field. The results show that the highest velocity peak for all cases is obtained at x = 0.5 m and the lowest at x = 3.5 m. The velocity profiles development remains similar when increasing the flow rate. For the zone evaluation, the results show that Case 1 and 2 (V = 20 L/s) meet the requirement of not exceeding 0.15 m/s during the heating season in the occupied zone according the BBR standard both for same-side and opposite-side configurations. For Case 4, the optimal placement of the inlets is opposite to each other when V = 30 L/s for the BBR requirements. Case 1, 2, 3, 4, 5, and 7 all meet the requirement of not exceeding 0.25 m/s during the cooling season both for the same-side and opposite-side configurations. For Case 8, the optimal placement of the inlets is opposite to each other when V = 50 L/s.
|
|
| 10. |
- Ameen, Arman, 1976-, et al.
(författare)
-
Numerical investigation of indoor thermal comfort and air quality for an office equipped with corner impinging jet ventilation
- 2023
-
Ingår i: Advances in Building Energy Research. - : Taylor & Francis. - 1751-2549 .- 1756-2201. ; 17:5, s. 578-604
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigates the feasibility of using only corner impinging jet ventilation (CIJV) for heating and cooling a medium-sized office space with two occupants while maintaining adequate indoor thermal comfort and air quality compared to traditional mixing ventilation systems. This study examines what impact various outdoor temperatures, ranging from −15°C to 25°C, have on an office environment in terms of indoor thermal comfort and air quality. Three different workspace positions were evaluated. The results show that the CIJV system meets the ASHRAE thermal comfort standards for all three positions. In terms of indoor air quality, CIJV performs better than traditional mixing systems, with improved mean age of air and ACE values. This study concludes that CIJV can be used both close and far away from the supply inlets and still provide adequate indoor thermal comfort and air quality during both cooling and heating season.
|
|
