Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 19) Show all publications
Ploskic, A., Wang, Q. & Sadrizadeh, S. (2019). A holistic performance evaluation of ventilation radiators – An assessment according to EN 442-2 using numerical simulations. Journal of Building Engineering, 25, Article ID 100818.
Open this publication in new window or tab >>A holistic performance evaluation of ventilation radiators – An assessment according to EN 442-2 using numerical simulations
2019 (English)In: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 25, article id 100818Article in journal (Refereed) Published
Abstract [en]

This research explored the importance of airflow rate and convector plate design on the operational performance of heating radiators equipped with an air device (ventilation radiators). The radiator was analyzed according to European Norm EN 442-2 using numerical simulations. The largest benefit of using staggered convector plates was the more efficient preheating of the incoming outdoor air supply. With this plate design, the evaluated radiator increased the temperature of the incoming airflow of 10 l/s from -5 °C to 26 °C with water supply/return temperatures of 45 °C/35 °C. With these water temperatures, the radiator was able to cover a room heat loss of 34 W/m2 floor area. However, the design of the convector plate alone was found to have a limited impact on the heat output from the radiator. Neither did the plate design significantly affect the uniformity of heat distribution nor the vertical temperature stratification inside the room. The results also showed that ventilation radiators might cover a building heating load (kW) with a lower supply water temperature but not necessarily give a lower annual energy use (kWh) for the space heating of a building.

Place, publisher, year, edition, pages
I: Elsevier, 2019
Keywords
Radiator, Low-temperature heating, Ventilation, Heat transfer, Staggered channels, Energy
National Category
Energy Engineering
Research subject
Energy Technology; Energy Technology; Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-258927 (URN)10.1016/j.jobe.2019.100818 (DOI)000477702200050 ()2-s2.0-85067571725 (Scopus ID)
Funder
Svenska Byggbranschens Utvecklingsfond (SBUF), 13122
Note

QC 20190913

Available from: 2019-09-11 Created: 2019-09-11 Last updated: 2019-09-13Bibliographically approved
Xue, Y., Liu, W., Wang, Q. & Bu, F. (2019). Development of an integrated approach for the inverse design of built environment by a fast fluid dynamics-based generic algorithm. Building and Environment, 160, Article ID 106205.
Open this publication in new window or tab >>Development of an integrated approach for the inverse design of built environment by a fast fluid dynamics-based generic algorithm
2019 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 160, article id 106205Article in journal (Refereed) Published
Abstract [en]

It is essential to further design built environments with improved thermal comfort level, air quality, and reduced energy consumption of the HVAC system. The CFD-based GA was able to identify the global optimal design, but this method requires numbers of CFD simulations which is time consuming. Besides, there is no general rule in determining the critical parameters of GA, such as population size, mutation rate, and crossover rate. Therefore, this study adopted the FFD instead of CFD and developed the FFD-based GA in OpenFOAM. By testing the FFD-based GA in designing the thermal environment in an office with displacement ventilation, it was found that the FFD-based GA had the similar performance with that of the CFD-based GA and saved more than 75% computational effect. Making use of the efficiency of the FFD-based GA, this investigation tested the effect of population size, mutation rate, and crossover rate on the inverse design by GA. In the same design case, the appropriate population size was and mutation rate was m = 0.1, while the crossover rate had no general effect on the inverse design.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Population size, Mutation rate, Crossover rate, Optimal design
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-255363 (URN)10.1016/j.buildenv.2019.106205 (DOI)000474204100019 ()2-s2.0-85067419693 (Scopus ID)
Note

QC 20190806

Available from: 2019-08-06 Created: 2019-08-06 Last updated: 2019-08-06Bibliographically approved
Nourozi, B., Wang, Q. & Ploskic, A. (2019). Energy and defrosting contributions of preheating cold supply air in buildings with balanced ventilation. Applied Thermal Engineering, 146, 180-189
Open this publication in new window or tab >>Energy and defrosting contributions of preheating cold supply air in buildings with balanced ventilation
2019 (English)In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 146, p. 180-189Article in journal (Refereed) Published
Abstract [en]

Residential wastewater is a constant and available source for saving energy. This paper mainly investigated the possibility of utilizing wastewater heat to reduce ventilation heat load. Swedish residential buildings are to a significant extent served by mechanical ventilation with heat recovery (MVHR) systems. MVHR in airtight buildings has greatly reduced ventilation heat loads, especially in cold climate countries such as Sweden. However, cold outdoor air might lead to frost formation in heat recovery exchangers which increases the energy use. Therefore, this study focused on reducing the defrosting need by preheating the incoming cold outdoor air to MVHR during the coldest days. The effects of preheating the incoming air to MVHR on ventilation heat load and annual ventilation heating demand were also studied. It was found that the heat recovery efficiency of MVHR is the most decisive factor in rating the performance of the combined system with an air preheater. Contributions of the studied air preheater to annual energy savings were negligible. On the other hand, the reduction of the initial defrosting need was significant. The obtained results showed that the defrosting need in a building located in central Sweden in two cases of an MVHR system equipped with a rotary heat exchanger/plate heat exchanger was eliminated/reduced to one-third. The defrosting need was reduced by 50% in northern Sweden for both cases.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Balanced ventilation, Heat recovery efficiency, Defrosting reduction, Wastewater heat recovery, Multi-family buildings, Energy saving
National Category
Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-241185 (URN)10.1016/j.applthermaleng.2018.09.118 (DOI)000454465900017 ()2-s2.0-85054338548 (Scopus ID)
Note

QC 20190121

Available from: 2019-01-21 Created: 2019-01-21 Last updated: 2019-08-30Bibliographically approved
Härer, S., Nourozi, B., Wang, Q. & Ploskic, A. (2019). Frost reduction in mechanical balanced ventilation by efficient means of preheating cold supply air. In: : . Paper presented at The 10th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings (IAQVEC), 5-7 September 2019, Bari, Italy.
Open this publication in new window or tab >>Frost reduction in mechanical balanced ventilation by efficient means of preheating cold supply air
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

This study has focused on evaluating the financial potential of wastewater and geothermal heat recovery systems in a multi-family building. The recovered heat was used to improve the performance of mechanical ventilation with heat recovery (MVHR) system during the coldest days in central Sweden. The main issue, which was targeted with these solutions, was to reduce frost formation in the system and hence increase its thermal efficiency. By looking at the life cycle cost over a lifespan of 20 years, the observed systems were being evaluated economically. Furthermore, statistical analyses were carried-out to counter the uncertainty that comes with the calculation. It was found that the studied wastewater systems have a high possibility of generating savings in this period, while the one fed by geothermal energy is less likely to compensate for its high initial cost. All designed systems however, managed to reduce operational cost by 35-45% due to lower energy usage.

National Category
Building Technologies
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-257495 (URN)
Conference
The 10th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings (IAQVEC), 5-7 September 2019, Bari, Italy
Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2019-12-20Bibliographically approved
Nourozi, B., Wang, Q. & Ploskic, A. (2019). Identifying frost threshold in a balanced mechanical ventilation system by inlet and exhaust air temperature control. In: : . Paper presented at The 11th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC2019).
Open this publication in new window or tab >>Identifying frost threshold in a balanced mechanical ventilation system by inlet and exhaust air temperature control
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Frosting is a common issue in air-to-air heat recovery exchangers installed in buildings in cold climate countries. Further to the developed defrosting methods, frost prevention by preheating the outdoor air can reduce the energy usage in buildings. In this study, residential wastewater as a renewable heat source is used to preheat the outdoor air. Due to limited wastewater hourly flowrate and the impact of preheated air temperature on the efficiency of heat exchanger, controlling the preheating temperature is of utmost importance. In this investigation, preheated and exhaust air temperatures are monitored to generate an operational signal to the wastewater circulation pump. The cold surface at the heat exchanger and the dew point of the return air are analyzed to comprehend the condensation and frosting temperatures. The results show that in case of 30% relative humidity in the return air, the frosting threshold is at preheated and exhaust air temperatures below -2.2°C and 2.1°C, respectively. Using these temperatures as controlling parameters, the frosting period has decreased by 23%.

Keywords
Balanced mechanical ventilation; Frosting; Frosting threshold; Wastewater heat recovery; Energy saving
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-255622 (URN)
Conference
The 11th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC2019)
Note

QC 20190926

Available from: 2019-08-02 Created: 2019-08-02 Last updated: 2019-12-20Bibliographically approved
Nourozi, B., Härer, S., Wang, Q. & Ploskic, A. (2019). Life cycle cost analysis of air preheating systems using wastewater and geothermal energy. The REHVA European HVAC Journal, 56(1), 47-51
Open this publication in new window or tab >>Life cycle cost analysis of air preheating systems using wastewater and geothermal energy
2019 (English)In: The REHVA European HVAC Journal, ISSN 1307-3729, Vol. 56, no 1, p. 47-51Article in journal (Other (popular science, discussion, etc.)) Published
Abstract [en]

Frosting is a common problem in air handling units in buildings in cold climates. Tacklingthis problem is so far achieved by using considerable amount of energy while during thisprocess, the indoor air quality is compromised. This article presents the Life Cycle Cost(LCC) assessment of a preventive solution for frosting using two renewable heat sources.

Place, publisher, year, edition, pages
Üsküdar/İstanbul, Turkey: , 2019
Keywords
wastewater heat recovery, geothermal heating, energy saving, balanced mechanical ventilation, Life Cycle Cost (LCC)
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-253065 (URN)10.13140/RG.2.2.32067.86563 (DOI)
Note

QC 20190802

Available from: 2019-06-13 Created: 2019-06-13 Last updated: 2019-08-02Bibliographically approved
Nourozi, B., Wang, Q. & Ploskic, A. (2019). Maximizing thermal performance of building ventilation using geothermal and wastewater heat. Resources, Conservation and Recycling, 143, 90-98
Open this publication in new window or tab >>Maximizing thermal performance of building ventilation using geothermal and wastewater heat
2019 (English)In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 143, p. 90-98Article in journal (Refereed) Published
Abstract [en]

An efficient use of waste heat recovery and geothermal heat can play an important role in lowering the overall energy use of buildings. This study evaluated the potential of geothermal energy and heat recovery from residential wastewater to reduce the energy need of building-ventilation in cold climates. The performance of the mechanical ventilation with heat recovery (MVHR) system in a multi-family building located in central Sweden was studied. The focus of the investigation was on reduction of frosting in the air handling unit during the coldest months. Three configurations of one air preheating system fed by two renewable heat sources, wastewater and geothermal energy, were studied. It was found that compared to building without an air preheating system, the suggested air preheating systems reduced the defrosting time to 25%. By controlling and maintaining the preheated air temperature to slightly above the defrosting start, air heat recovery efficiency of MVHR above 80% was achieved for 90% of the studied time during heating season when frosting occurs. The energy need for the circulation pumps in the suggested air preheating systems was 5% of the recovered thermal energy from wastewater. The simulation results suggested that the air preheating system using wastewater heat recovery with a temperature-stratified storage tank was the most efficient one among the studied systems.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2019
Keywords
Renewables, Wastewater heat recovery, Geothermal heating, Balanced mechanical ventilation, Sustainability, Energy saving
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-245125 (URN)10.1016/j.resconrec.2018.12.025 (DOI)000458222600010 ()2-s2.0-85058947734 (Scopus ID)
Note

QC 20190315

Available from: 2019-03-15 Created: 2019-03-15 Last updated: 2019-08-30Bibliographically approved
Nourozi, B., Wang, Q. & Ploskic, A. (2019). Preheating Cold Supply Air to Mechanical Balanced Ventilation using Wastewater or Passive Geothermal Energy. In: : . Paper presented at The 16th International Building Performance Simulation Association (IBPSA), 2-4 September 2019, Rome, Italy.
Open this publication in new window or tab >>Preheating Cold Supply Air to Mechanical Balanced Ventilation using Wastewater or Passive Geothermal Energy
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

This study investigated the thermal potential of two renewable heat sources, residential wastewater and geothermal energy, for preheating the incoming air to the air-handling unit (AHU) in a multi-family building. The main purpose of preheating the inlet air was to avoid the frost formation inside AHU due to low outdoor temperatures during winter. Wastewater extraction flowrate and temperature, as two design parameters, were studied in detail by employing two types of wastewater storage tanks.The suggested outdoor air preheating systems equally reduced the defrosting period to 26% compared to the mechanical ventilation with heat recovery system (MVHR) without air preheating. The system that utilized a temperature stratified wastewater storage tank provided a higher ratio of heat output to electricity input. The other outdoor air preheating system, which was equipped with an unstratified wastewater storage tank, provided a lower ratio of heat output to pumping power. However, this ratio was not disturbed by variations in outdoor air temperature.

National Category
Building Technologies
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-257493 (URN)
Conference
The 16th International Building Performance Simulation Association (IBPSA), 2-4 September 2019, Rome, Italy
Note

QC 20190926

Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2019-12-20Bibliographically approved
Ploskic, A. & Wang, Q. (2018). Evaluating the potential of reducing peak heating load of a multi-family house using novel heat recovery system. Applied Thermal Engineering, 130, 1182-1190
Open this publication in new window or tab >>Evaluating the potential of reducing peak heating load of a multi-family house using novel heat recovery system
2018 (English)In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 130, p. 1182-1190Article in journal (Refereed) Published
Abstract [en]

The current study evaluated the potential of reducing ventilation heat load by using heat from waste water in mechanical ventilation with heat recovery (MVHR) served Swedish residential buildings. A typical Swedish low-energy, multi-family house locating at the northern part of Sweden was selected to present the analysis. The building was locating at the northern part of Sweden and was served by mechanical ventilation with heat recovery (MVHR). The data from on-site measurements and analytical model were applied to evaluate the reduction potential of the suggested heat recovery system. The study focused on the evaluation of benefit of using an air preheater in front of the existing MVHR system. Two different sizes of an air preheater design: Small air preheater with the size of 0.4 m x 0.4 m x 0.4 m (AP(0.4mx0.4 mx0.4 m)), feed with waste water flow of 0.15 kg/s (from storage tank to air preheater); and a large air preheater with the size of 0.8 m x 0.8 m x 0.4 m (AP(0.8 mx0.8 mx0.4 m)), feed with waste water flow of 0.2 kg/s. It was found that the heat recovery efficiency of MVHR is the core to determine the selection of air preheaters. In comparison to the MVHR without air preheater, maximum air supply temperature improvements of 25% and 41% were found from AP(0.4mx0.4 mx0.4 m) and AP(0.8 mx0.8 mx0.4 m), respectively. The studied system reached its highest contributions when the heat recovery efficiency of MVHR was between 80% and 85%. On average, AP(0.4mx0.4 mx0.4 m) can reduced the peak heat load up to 27%. AP(0.8 mx0.8 mx0.4 m) can reduce the peak heat load up to 40% in the studied climate.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Residential waste water, Heat recovery, Balanced ventilation, Peak heat load, Low-energy multi-family houses
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-223511 (URN)10.1016/j.applthermaleng.2017.11.072 (DOI)000424177600104 ()2-s2.0-85034949075 (Scopus ID)
Funder
Swedish Energy Agency
Note

QC 20180222

Available from: 2018-02-22 Created: 2018-02-22 Last updated: 2018-03-14Bibliographically approved
Ploskic, A., Wang, Q. & Sadrizadeh, S. (2018). Mapping Relevant Parameters for Efficient Operation of Low-Temperature Heating Systems in Nordic Single-Family Dwellings. Applied Sciences, 8(10), Article ID 1973.
Open this publication in new window or tab >>Mapping Relevant Parameters for Efficient Operation of Low-Temperature Heating Systems in Nordic Single-Family Dwellings
2018 (English)In: Applied Sciences, E-ISSN 2076-3417, Vol. 8, no 10, article id 1973Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to map the parameters that have the greatest impact on the environmental impact of heating systems usually used in Nordic single-family dwellings. The study focused on mapping the technical requirements for efficient operation of heating systems in a broader context. The results suggest that the ability of a heating system to be operated with a low-temperature water supply depends to a large extent on the heating demand of a building. It was shown that an increase in the water flow rate in hydronic circuits would significantly increase the thermal efficiency from analyzed heating systems. This increase would not increase the pumping power need, nor would it create noise problems in distribution network if the distribution pipes and thermostatic valves were properly selected. However, this increase in water flow rate improved the efficiency of considered closed-loop heat pump. It was further shown that the efficiency of the heat pump could be additionally improved by halving the energy needs for the domestic hot-water and circulators. The main conclusion from this study is that exergy usage, CO2 emission and thereby environmental impact are significantly lower for heating systems that are operated with small temperature drops.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
low-temperature heating, energy efficiency, CO2 emissions, heat pump, hydraulic losses, system analysis
National Category
Medical Engineering
Identifiers
urn:nbn:se:kth:diva-239111 (URN)10.3390/app8101973 (DOI)000448653700268 ()2-s2.0-85055107835 (Scopus ID)
Note

QC 20181120

Available from: 2018-11-20 Created: 2018-11-20 Last updated: 2019-08-20Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6266-8485

Search in DiVA

Show all publications