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Cehlin, M., Karimipanah, T., Larsson, U. & Ameen, A. (2019). Comparing thermal comfort and air quality performance of two active chilled beam systems in an open-plan office. Journal of Building Engineering, 22, 56-65
Open this publication in new window or tab >>Comparing thermal comfort and air quality performance of two active chilled beam systems in an open-plan office
2019 (English)In: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 22, p. 56-65Article in journal (Refereed) Published
Abstract [en]

The traditional air distribution and supply devices in ventilated rooms are not always able to effectively remove excess heat from the space. Therefore, chilled beams, especially the active systems, are used to achieve the desired cooling demand. The focus of this paper was the potential benefit of a newly designed active chilled beam (ACB) system, to improve heat removal effectiveness local thermal condition and indoor air quality in the occupants’ breathing zone. The system based on 1-way flow design (1W-ACB) was installed in an open-plan office and its performance was studied by analysing the temperatures, velocities and tracer gas concentrations in predetermined risky zones. The system was compared against a traditional 4-way flow design (4W-ACB).

The obtained results showed that heat removal effectiveness was slightly higher for the 1W-ACB system compared to the 4W-ACB system. The local thermal condition was very good close to the workstations when using 1W-ACB. The benefits of the new system were also shown in the occupied zone by analysing the mean age of air and air-change effectiveness (ACE) in the breathing level at the workstation locations. The 1W-ACB system provided air with lower mean age (fresher air), and therefore higher ACE, near the breathing zone at the workstations compared to the 4W-ACB. On the other hand, the 4W-ACB system had the advantage of providing high thermal and mean age of air uniformity throughout the room.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Active Chilled Beam, Air Change Effectiveness, Heat Removal Effectiveness
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-28583 (URN)10.1016/j.jobe.2018.11.013 (DOI)2-s2.0-85057839765 (Scopus ID)
Available from: 2018-11-22 Created: 2018-11-22 Last updated: 2019-01-07Bibliographically approved
Bakhtiari, H., Akander, J. & Cehlin, M. (2019). Evaluation of Thermal Comfort in a Historic Building Refurbished to an Office Building with Modernized HVAC Systems. Advances in Building Energy Research
Open this publication in new window or tab >>Evaluation of Thermal Comfort in a Historic Building Refurbished to an Office Building with Modernized HVAC Systems
2019 (English)In: Advances in Building Energy Research, ISSN 1751-2549, E-ISSN 1756-2201Article in journal (Refereed) Accepted
Keywords
Thermal comfort, historic building, HVAC
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-29442 (URN)10.1080/17512549.2019.1604428 (DOI)
Funder
Knowledge Foundation, 20150133
Available from: 2019-04-05 Created: 2019-04-05 Last updated: 2019-04-05
Ameen, A., Cehlin, M., Larsson, U. & Karimipanah, T. (2019). Experimental investigation of ventilation performance of different air distribution systems in an office environment – cooling mode. Energies, 12(7), Article ID 1354.
Open this publication in new window or tab >>Experimental investigation of ventilation performance of different air distribution systems in an office environment – cooling mode
2019 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 7, article id 1354Article in journal (Refereed) Published
Abstract [en]

The performance of a newly designed corner impinging jet air distribution method with an equilateral triangle cross section was evaluated experimentally and compared to that of two more traditional methods (mixing and displacement ventilation). At nine evenly chosen positions with four standard vertical points, air velocity, turbulence intensity, temperature, and tracer gas decay measurements were conducted for all systems. The results show that the new method behaves as a displacement ventilation system, with high air change effectiveness and stratified flow pattern and temperature field. Both local air change effectiveness and air exchange effectiveness of the corner impinging jet showed high quality and promising results, which is a good indicator of ventilation effectiveness. The results also indicate that there is a possibility to slightly lower the airflow rates for the new air distribution system, while still meeting the requirements for thermal comfort and indoor air quality, thereby reducing fan energy usage. The draught rate was also lower for corner impinging jet compared to the other tested air distribution methods. The findings of this research show that the corner impinging jet method can be used for office ventilation.

Keywords
Corner impinging jet, mixing ventilation, displacement ventilation, tracer gas, air exchange effectiveness, air change effectiveness, draught rate
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-29443 (URN)10.3390/en12071354 (DOI)
Available from: 2019-04-05 Created: 2019-04-05 Last updated: 2019-04-09
Ameen, A. & Cehlin, M. (2019). Reducing Energy Usage in Multi-family Housing. In: Proceedings of 9th International Conference on Future Environment and Energy, January 9-11, Osaka, Japan: . Paper presented at 9th International Conference on Future Environment and Energy, 9-11 January 2019, Osaka, Japan. Japan
Open this publication in new window or tab >>Reducing Energy Usage in Multi-family Housing
2019 (English)In: Proceedings of 9th International Conference on Future Environment and Energy, January 9-11, Osaka, Japan, Japan, 2019Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

The energy usage in residential sector have been around 22% of the total energy use in the world and increasing due to the population growth and higher living standards. The energy sources for this are made up primarily of non-renewable energy resources which generates a large amount of global greenhouse gases. A lot of countries have implemented various regulations and rules to reduce the energy usage in buildings and promoting the use of renewable energy technologies. This paper presents a parametric study of a typical multi-family building in its pre-design stage. The climate location used is Sweden (Gothenburg) and Japan (Osaka). The aim of the study is to compare various configurations and to examine how they affect the energy use. The most interesting configurations are the use of heat pump and solar cells. Other configurations that are examined are infiltration levels, pressure coefficients, wind impact, ventilation with heat recovery, ventilation scheduling, building orientation and finally changing U-values in the building material. Results of this study show that the energy saving, by utilizing a heat pump and solar panels, can reduce the total energy use by 34.9% for Gothenburg and 32% for Osaka. The results also show that the difference in total energy use between the two cities reduce substantially (3% difference) when utilizing a heat pump in combination with solar panels.

Place, publisher, year, edition, pages
Japan: , 2019
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-29391 (URN)
Conference
9th International Conference on Future Environment and Energy, 9-11 January 2019, Osaka, Japan
Available from: 2019-03-18 Created: 2019-03-18 Last updated: 2019-03-25Bibliographically approved
Vachaparambil, K. J., Cehlin, M. & Karimipanah, T. (2018). Comparative Numerical Study of the Indoor Climate for Mixing and Confluent Jet Ventilation Systems in an Open-plan Office. In: Proceedings of the 4th international Conference on Building Energy & Environment: . Paper presented at COBEE2018, 4th international Conference on Building Energy & Environment, 5-9 February 2018, Melbourne, Australia (pp. 73-78). Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia
Open this publication in new window or tab >>Comparative Numerical Study of the Indoor Climate for Mixing and Confluent Jet Ventilation Systems in an Open-plan Office
2018 (English)In: Proceedings of the 4th international Conference on Building Energy & Environment, Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia , 2018, p. 73-78Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia, 2018
Keywords
Confluent jet ventilation
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-26568 (URN)978-0-646-98213-7 (ISBN)
Conference
COBEE2018, 4th international Conference on Building Energy & Environment, 5-9 February 2018, Melbourne, Australia
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2018-05-21Bibliographically approved
Andersson, H., Cehlin, M. & Moshfegh, B. (2018). Experimental and numerical investigations of a new ventilation supply device based on confluent jets. Building and Environment, 137, 18-33
Open this publication in new window or tab >>Experimental and numerical investigations of a new ventilation supply device based on confluent jets
2018 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 137, p. 18-33Article in journal (Refereed) Published
Abstract [en]

In developed countries, heating, ventilation, air conditioning (HVAC) systems account for more than 10% of national energy use. The primary function of a HVAC system is to create proper indoor environment. A number of ventilation strategies have been developed to minimize HVAC systems’ energy use whilst still maintaining a good indoor environment. Among these strategies are confluent jet ventilation and variable air volume. In this study, an air supply device with a novel nozzle design that uses both of the above-mentioned strategies was investigated both experimentally and numerically at three different airflow rates. The results from the numerical investigation using the SST k - ω turbulence model regarding velocities and flow patterns are validated by experimental data carried out by Laser Doppler Anemometry. The results from both studies show that the flow pattern and velocity in each nozzle is directly dependent on the total airflow rate. However, the flow pattern does not vary between the three different airflow rates. The numerical investigation shows that velocity profiles for each nozzle have the same pattern regardless of the airflow rate, but the magnitude of the velocity profile increases as the airflow increases. Thus, a supply device of this kind could be used for variable air volume and produce confluent jets for the airflow rates investigated.

Keywords
Confluent jets, Laser Doppler anemometry, SST k, Validation study, Ventilation supply device, ω turbulence model
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-26571 (URN)10.1016/j.buildenv.2018.03.038 (DOI)000433649700003 ()2-s2.0-85044917956 (Scopus ID)
Funder
Knowledge Foundation
Note

Funding: University of Gavle, Repus Ventilation AB and the Knowledge Foundation

Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2019-02-13Bibliographically approved
Cehlin, M. (2018). Mapping tracer gas concentrations using a modified Low Third Derivative method: numerical study. The International Journal of Ventilation
Open this publication in new window or tab >>Mapping tracer gas concentrations using a modified Low Third Derivative method: numerical study
2018 (English)In: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044Article in journal (Refereed) Epub ahead of print
Abstract [en]

In indoor applications, computed tomography is the process of transforming a network of intersecting attenuation measurements into a spatially resolved two-dimensional concentration map. In this study the Low Third Derivative method (LTD) was numerically evaluated and optimized for different conditions. A modified version of the LTD algorithm (LTDm) was proposed and evaluated against the original version. Eight test maps were reconstructed under different conditions, such as weight ratio, pixel resolution, beam density and measurement noise. Performance of both LTD algorithms was found to be intimately related to the number of peaks and complexity in the test map and the steepness of the peaks. The LTDm algorithm improved the quality, especially for concentration maps including steep gradients and regions with very low concentrations. The LTDm method heavily lessened aliasing distortions and efficiently minimized the effects of noise.

Keywords
Computed tomography, numerical study, reconstruction algorithm, tracer gas distribution
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-26569 (URN)10.1080/14733315.2018.1462935 (DOI)2-s2.0-85045619672 (Scopus ID)
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2018-06-05Bibliographically approved
Haghshenas, S., Sajadi, B. & Cehlin, M. (2018). Multi-Objective Optimization of Impinging Jet Ventilation Systems: Taguchi Based CFD Method. Building Simulation, 11(6), 1207-1214
Open this publication in new window or tab >>Multi-Objective Optimization of Impinging Jet Ventilation Systems: Taguchi Based CFD Method
2018 (English)In: Building Simulation, ISSN 1996-3599, E-ISSN 1996-8744, Vol. 11, no 6, p. 1207-1214Article in journal (Refereed) Published
Abstract [en]

This paper presents a Taguchi method-based approach that can optimize the operating performance of impinging jet ventilation (IJV) systems with limited computational fluid dynamics (CFD) simulation results. The Taguchi optimization calculation finds the best operating design for the weighted overall objective function as a presenter of the multi-objective function problem. The method is used to optimize the operating characteristics of an IJV system considering the factors of supply air temperature, level of the return air vent and percentage of the air exhausted through the ceiling to achieve an overall best performance of thermal comfort, indoor air quality (IAQ) and system energy performance as the objective functions. The study indicates the contribution percentage for each factor in each objective function. The level of the return air vent, the supply air temperature, and the percentage of air exhausted through the ceiling have a contribution of 35.8%, 28.5%, and 35.8% in the objective functions, respectively. Based on the results, the best performance of the IJV system happens when the inlet air temperature is 18 °C, the height of the return air vent is 2 m above the floor, and the percentage of air exhausted through the ceiling is 22.5%.

Keywords
impinging jet ventilation (IJV), thermal comfort, indoor air quality, energy performance, Taguchi method, optimization
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-26570 (URN)10.1007/s12273-018-0450-z (DOI)000451924600010 ()2-s2.0-85056574558 (Scopus ID)
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2019-01-07Bibliographically approved
Cehlin, M., Larsson, U. & Chen, H. (2018). Numerical investigation of Air Change Effectiveness in an Office Room with Impinging Jet Ventilation. In: K. Inthavong*, C.P Cheung, G. Yeoh, J.Y. Tu (Ed.), Proceedings of the 4th international Conference on Building Energy & Environment: . Paper presented at COBEE2018, 4th international Conference on Building Energy & Environment,5-9 February 2018, Melbourne, Australia (pp. 641-646). Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia
Open this publication in new window or tab >>Numerical investigation of Air Change Effectiveness in an Office Room with Impinging Jet Ventilation
2018 (English)In: Proceedings of the 4th international Conference on Building Energy & Environment / [ed] K. Inthavong*, C.P Cheung, G. Yeoh, J.Y. Tu, Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia , 2018, p. 641-646Conference paper, Published paper (Refereed)
Abstract [en]

Providing occupant comfort and health with minimum use of energy is the ultimate purpose of heating, ventilating and air conditioning systems. This paper presents the air-change effectiveness (ACE) within a typical office room using impinging jet ventilation (IJV ) in combination with chilled ceiling (CC) under different heat loads ranging from 6.5 - 51 W per square meter floor area. In this study, a validated CFD model based on the v2f turbulence model is used for the prediction of air flow pattern and ACE. The interaction effect of chilled ceiling and heat sources results in a complex flow with air circulation. The thermal plumes and air circulation in the room result in a variation of ACE within the room but also close to the occupant. For all studied cases, ACE is above 1.2 close to the occupants, indicating that IJV is more energy efficient than mixing ventilation.

Place, publisher, year, edition, pages
Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia, 2018
Keywords
Impinging jet ventilation
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-26567 (URN)978-0-646-98213-7 (ISBN)
Conference
COBEE2018, 4th international Conference on Building Energy & Environment,5-9 February 2018, Melbourne, Australia
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2018-09-17Bibliographically approved
Khosravi Bakhtiari, H., Cehlin, M. & Akander, J. (2018). Thermal Comfort in Office Rooms in a Historic Building with Modernized HVAC Systems. In: Kiao Inthavong,Chi Pok Cheung, Guan Yeoh, Jiyuan Tu (Ed.), Proceedings of the 4th International Conference On Building Energy & Environment, COBEE 2018: RMIT University, Melbourne, Australia, Feb 5-9th 2018. Paper presented at 4th International Conference On Building Energy & Environment, COBEE 2018, 5-9 February 2018, Melbourne, Australia (pp. 683-688). Melbourne: Conference On Building Energy & Environment, Article ID 230.
Open this publication in new window or tab >>Thermal Comfort in Office Rooms in a Historic Building with Modernized HVAC Systems
2018 (English)In: Proceedings of the 4th International Conference On Building Energy & Environment, COBEE 2018: RMIT University, Melbourne, Australia, Feb 5-9th 2018 / [ed] Kiao Inthavong,Chi Pok Cheung, Guan Yeoh, Jiyuan Tu, Melbourne: Conference On Building Energy & Environment , 2018, p. 683-688, article id 230Conference paper, Published paper (Refereed)
Abstract [en]

SUMMARY

Envelopes with low thermal performance are common characteristics in European historic buildings, leading to higher energy demand and insufficient thermal comfort. This paper presents the results of a study on thermal comfort in the historic office building of City Hall in Gävle, Sweden. It is equipped with two modern heat recovery ventilation systems with displacement ventilation supply devices in offices. District heating network heats the building via pre-heat supply air and radiators. Summer cooling comes from electric heat pump, rejecting heat into the exhaust ventilation air. A building management system controls HVAC equipment. Methodology includes on-site measurements, data logging on management system and evaluating the occupants’ perception of a summer and a winter period indoor environment using a standardized questionnaire. In conclusion, thermal comfort in this historic building is poor although it is equipped with modern ventilation systems and there should be possibilities for improving comfort, by improved control strategies.

Keywords — Historic Buildings, On-site Measurements, Standardized Questionnaire, Thermal Comfort

Place, publisher, year, edition, pages
Melbourne: Conference On Building Energy & Environment, 2018
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-26550 (URN)978-0-646-98213-7 (ISBN)
Conference
4th International Conference On Building Energy & Environment, COBEE 2018, 5-9 February 2018, Melbourne, Australia
Available from: 2018-05-07 Created: 2018-05-07 Last updated: 2018-06-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2023-689x

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