mdh.sePublikationer
Ändra sökning
Avgränsa sökresultatet
1 - 12 av 12
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Akbari, Keramatollah
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Impact of Radon Ventilation on Indoor Air Quality and Building Energy saving2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Industrial living is caused much people do live and work in closed and confined places; offices and residential buildings. This is why in this new world more fresh air which is generally provided by forced ventilation plays a vital role in living of human being. Furthermore because of many different indoor pollutants, like radon and artificial pollutants, the amount of fresh air and in turn the energy consumption has increased. This energy consumption related to ventilation has reached up to about 30 percent of energy used of building section. So making interaction between indoor air quality (IAQ) and optimization of energy saving is a necessary work.  Radon as a natural pollutant is occurred in environment and in many countries threatens people health whereas is called the second causes of cancer. For reducing radon concentration in residential building at the acceptable level forced ventilation is used usually. Ventilation can improve IAQ but in the other side would increase the energy consumption in building sector and just now the contribution of ventilation exceeds up 50 percent of building sector's share. The aim of this thesis is to study the impact of ventilation on indoor radon by using Computational Fluid Dynamics (CFD) to achieve indoor air quality and energy efficiency. Application of CFD as a new technology, because of its cost and time savings, and on the other side, of its flexibility and precision is  increasingly grown and can be used as a very important and valuable tool for the prediction and measurement of radon distribution in a ventilated building . Currently, measurement techniques and proposed standards and regulations of indoor pollutants and ventilation, particularly related to indoor radon cannot be able to provide a secure, safe and energy efficient indoor climate. This is why the indoor airflow distribution is very complex and with changing building geometry and operation condition, the treatment of air flow pattern, substantially would be changed, whereas the rules are usually independent of the buildings features. Furthermore, the indoor standards and regulations are based on average amount of pollutants in a room, whereas the pollutant distributions aren't identical and are varied throughout the room. Then the current techniques aren't so exactly valuable and acceptable.

    From different methods which is privilege to control pollutants, ventilation method is applicable in existing buildings. Designing effective ventilation can reduce radon concentration to very level low with regarding energy conservation remarks.

     

    This thesis presents results from simulation studies on ventilation and radon mitigation in residential buildings, in view points of indoor air quality and energy savings. The CFD technique is applied to predict, visualize and calculate of mixture radon-air flow. The distribution of indoor radon concentration, air velocity and room temperature also have considered together for achieving indoor air quality and energy saving. The results are also compared with the experimental data and related previous works.

     

    It was found that with increasing ventilation rate, the radon concentration is decreased, but the location of ventilation system is also important. From the simulation results, it is observed that within the ventilated room, there are some zones, which are good for living and somewhere is more polluted. The traditional radon detectors basically show the average value of radon content in 1m­3 of air. That is why detector measuring is not exact and safe.

     

    Simulation results proved that floor heat can be supported ventilation effect and speed up the mixture movement. Floor heating reinforces the buoyancy effect, which is useful to reduce radon content in the floor (seating area) and then lower ventilation rate can be applied.

  • 2.
    Akbari, Keramatollah
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Influence of residential ventilation on Radon mitigation with energy saving emphasis2009Ingår i:  PROCEEDINGS FROM SCIENTIFIC CONFERENCE ON GREEN ENERGY AND IT, 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    There are many indoor pollutants in the residential buildings. High insulation and tightness in buildings in order to increase energy efficiency and to lower energy costs is led to the indoor air quality problems. To provide sufficient fresh air and to promote indoor air quality at acceptable level, it is needed to increase ventilation rate to overcome such pollutants.  

    The aim of this paper is to study about energy efficient mechanical ventilation to overcome poor indoor air quality and energy consumption associated with radon ventilation.

     

    Ventilation is a good method to dilute radon contaminant and maintain indoor air quality, but in the other hand ventilation is account for about 50 percent of energy use in residential buildings. Designing the required rate and location of ventilation systems and also choosing the best type of ventilation strategies can be provided both indoor air quality (IAQ) and building energy savings (BES).

     Computational fluid dynamics technique as a useful tool can be used to simulate and visualize radon treatment and mechanical ventilation rates for optimizing energy consumption and achieving to indoor air quality.

    Results show that the exhaust fan installed in the middle another one in the left side have different impacts on distribution of radon contents in the room. Also when the rate of ventilation is changed from 7.5 l/s to 35 l/s the radon concentration will be decreased. By choosing the optimum features of ventilation system, energy saving can be obtained.

  • 3.
    Akbari, Keramatollah
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Simulation of Indoor Radon and Energy Recovery Ventilation Systems in Residential Buildings2015Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This study aims to investigate the effects of ventilation rate, indoor air temperature, humidity and using a heat recovery ventilation system on indoor radon concentration and distribution.

    Methods employed include energy dynamic and computational fluid dynamics simulation, experimental measurement and analytical investigations. Experimental investigations primarily utilize a continuous radon meter and a detached house equipped with a recovery heat exchanger unit.

    The results of the dynamic simulation show that the heat recovery unit is cost-effective for the cold Swedish climate and an energy saving of about 30 kWh per  floor area per year is possible, while it can be also used to lower radon level.

    The numerical results showed that ventilation rate and ventilation location have significant impacts on both radon content and distribution, whereas indoor air temperature only has a small effect on radon level and distribution and humidity has no impact on radon level but has a small impact on its distribution.

  • 4.
    Akbari, Keramatollah
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Mahmoudi, Jafar
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Effects of Heat Recovery Ventilation Systems on Indoor Radon2012Ingår i: PROCEEDINGS OF ECOS 2012 - THE 25TH INTERNATIONAL CONFERENCE ON EFFICIENCY, COST, OPTIMIZATION, SIMULATION AND ENVIRONMENTAL IMPACT OF ENERGY SYSTEMS / [ed] ECOS, 2012, , s. 10s. 1-10Konferensbidrag (Refereegranskat)
    Abstract [en]

    A heat recovery ventilation system enables us to control indoor conditions such as ventilation rate,

    temperature, relative humidity and pressure difference. These environmental conditions affect indoor radon

    levels.

    Computational fluid dynamics (CFD) is a powerful tool for predicting and visualizing radon content and indoor

    air quality and is cost effective in comparison with other methods such as full scale laboratory and gas trace

    techniques.

    In this study a mechanically balanced ventilation system and a continuous radon monitor (CRM) were used

    to measure the indoor ventilation rate and radon levels. In a numerical approach the FLUENT CFD package

    was used to simulate radon entry into the building and effects on indoor air conditions.

    The effects of different ventilation rates, indoor temperature and relative humidity on indoor radon

    concentrations were investigated in a one family detached house in Stockholm. Results of numerical studies

    indicated that changes of ventilation rate, indoor temperature and moisture by means of ventilation systems

    have significant effects on indoor radon content. Ventilation rate was inversely proportional to indoor radon

    concentration. Minimum radon levels were estimated in the range of thermal comfort, i.e. at 21 and

    relative humidity between 50-70%.

    The analytical solution was used to validate numeric results at 3 distinct air change rates. Comparisons

    between numerical and analytical results showed good agreement but there was poor agreement between

    simulations and measurement results due to the short measuring period.

  • 5.
    Akbari, Keramatollah
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Mahmoudi, Jafar
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Numerical Simulation of Radon Transport and Indoor Air Conditions Effects2012Ingår i: International journal of scientific and Engineering Research, ISSN 2229-5518, Vol. 3, nr 6, s. 1-10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Computational fluid dynamics (CFD) is a powerful tool for predicting and visualizing radon content and indoor air quality and is cost effective in comparison with other methods such as full scale laboratory and gas trace techniques. The intention of this article is to use CFD to simulate indoor radon distribution and ventilation effects. In this study a mechanically balanced ventilation system and a continuous radon monitor (CRM) were used to measure the indoor ventilation rate and radon levels. In a numerical approach the FLUENT CFD package was used to simulate radon entry into the building and effects on indoor air conditions. The effects of different ventilation rates, indoor temperature and relative humidity on indoor radon concentrations were investigated in a one family de-tached house in Stockholm. Results of numerical studies indicated that changes of ventilation rate, indoor temperature and moisture by means of ventila-tion systems have significant effects on indoor radon content. Ventilation rate was inversely proportional to indoor radon concentration. Minimum radon levels were estimated in the range of thermal comfort, i.e. at 21 and relative humidity between 50-70%. The analytical solution was used to validate numeric results at 3 distinct air change rates. Comparisons between numerical and analytical results showed good agreement but there was poor agreement between simulations and measurement results due to the short measuring period.

  • 6.
    Akbari, Keramatollah
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Mahmoudi, Jafar
    Simulation of Radon Mitigation in Residential Building2008Konferensbidrag (Refereegranskat)
  • 7.
    Akbari, Keramatollah
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Mahmoudi, Jafar
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Ghanbari, M.
    Sharif University of Technology, Tehran, Iran .
    Simulation of ventilation effects on indoor radon2013Ingår i: Management of environmental quality, ISSN 1477-7835, E-ISSN 1758-6119, Vol. 24, nr 3, s. 394-407Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: The purpose of this paper is to describe the use of computational fluid dynamics (CFD) to simulate indoor radon distribution and ventilation effects. This technique was used to predict and visualize radon content and indoor air quality in a one-family detached house in Stockholm. The effects of intake fans, exhaust fans and doors on radon concentration were investigated. Design/methodology/approach: In this study a mechanically balanced ventilation system and a continuous radon monitor (CRM) were used to measure the indoor ventilation rate and radon levels. In a numerical approach, the FLUENT CFD package was used to simulate radon entry into the building and ventilation effects. Findings: Results of the numerical study indicated that indoor pressure created by ventilation systems and infiltration through doors or windows have significant effects on indoor radon content. The location of vents was found to affect the indoor radon level and distribution. Research limitations/implications: It may be possible to improve any discrepancies found in this article by using a more refined representation of grids and certain boundary conditions, such as pressure and temperature differences between inside and outside and by considering some real situations in residential buildings and external situations. Originality/value: From the viewpoints of indoor air quality (IAQ) and energy savings, ventilation has two opposing functions; on the positive side it enhances IAQ and the establishment of thermal comfort, and on the negative side it increases energy consumption. This paper describes the search for a solution to cope with this contradiction.

  • 8.
    Akbari, Keramatollah
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Mahmoudi, Jafar
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Ghanbari, Mahdi
    Sharif University of Technology, Tehran, Iran.
    Influence of indoor air conditions on radon concentration in a detached house2013Ingår i: Journal of Environmental Radioactivity, ISSN 0265-931X, E-ISSN 1879-1700, ISSN ISSN 0265-931X, EISSN 1879-1700, Vol. 116, s. 166-173Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Radon is released from soil and building materials and can accumulate in residential buildings. Breathing radon and radon progeny for extended periods hazardous to health and can lead to lung cancer. Indoor air conditions and ventilation systems strongly influence indoor radon concentrations. This paper focuses on effects of air change rate, indoor temperature and relative humidity on indoor radon concentrations in a one family detached house in Stockholm, Sweden.In this study a heat recovery ventilation system unit was used to control the ventilation rate and a continuous radon monitor (CRM) was used to measure radon levels. FLUENT, a computational fluid dynamics (CFD) software package was used to simulate radon entry into the building and air change rate, indoor temperature and relative humidity effects using a numerical approach.The results from analytical solution, measurements and numerical simulations showed that air change rate, indoor temperature and moisture had significant effects on indoor radon concentration. Increasing air change rate reduces radon level and for a specific air change rate (in this work Ach = 0.5) there was a range of temperature and relative humidity that minimized radon levels. In this case study minimum radon levels were obtained at temperatures between 20 and 22 °C and a relative humidity of 50-60%

  • 9.
    Akbari, Keramatollah
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Mahmoudi, Jafar
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Öman, Robert
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Simulation of ventilation effects on indoor radon in a detached house2012Ingår i: WSEAS Transactions on Fluid Mechanics, ISSN 1790-5087, Vol. 7, nr 4, s. 146-155Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    CFD is widely used in indoor air quality, air flow pattern, indoor pollutant distribution and thermal comfort as a cost effective and powerful tool and it can be used to predict, estimate and visualize the indoor radon level. The intention of this article is to use computational fluid dynamics (CFD), as a standalone tool to simulate indoor radon distribution and ventilation effects. This technique can be used to predict and visualize radon content and indoor air quality throughout a one family detached house in Stockholm. In this study a mechanical balanced ventilation system and a continuous radon monitor (CRM) were also used to measure the indoor ventilation rate and radon levels. In numerical approach the FLUENT, CFD package was used to simulate radon entry into the building and ventilation effects. Results of numerical study indicated that indoor pressure made by means of ventilation systems and infiltration through door or window has significant effects on indoor radon content. It is observed that the location of vents can affect the indoor radon level, particularly in breathing (seating) zone. The analytic solution is used to validate numeric results at 3 distinct air change rates. The comparison amongst analytical, numerical and measurement results shows close agreement.

  • 10.
    Akbari, Keramatollah
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Oman, Robert
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Impacts of heat recovery ventilators on energy savings and indoor radon level2013Ingår i: Management of environmental quality, ISSN 1477-7835, E-ISSN 1758-6119, Vol. 24, nr 5, s. 682-694Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: This paper aims to investigate the impact of heat recovery ventilators (HRVs) on the energy use and indoor radon in a one family detached house. Heat recovery ventilation systems, because of reducing ventilation loss through recovered exhaust air, can play a good role in the effectiveness of ventilation to reduce energy use. In addition HRVs can maintain pressure balance and outdoor ventilation rate at a required level to mitigate indoor radon level. Design/methodology/approach: In this study, a multizone model of a detached house is developed in IDA Indoor Climate and Energy (IDA ICE 4.0). The model is validated using measurements regarding use of energy for heating, ventilation and whole energy use. The performance of the heat recovery ventilation system is examined with respect to radon mitigation and energy saving by measuring the radon concentration and analyzing the life cycle cost of a heat exchanger unit. Findings: The results of the measurements and dynamic simulation showed that the heat recovery ventilation system could lead to 74 per cent energy savings of the ventilation loss, amounting to about 30 kWh m-2 per year. Life cycle cost analysis used for assessing total costs and the result showed that using this system is quite cost-effective and investment would payback during 12 years. Research limitations/implications: Limitations of this study generally refer to radon measurement and simulation because of radon complex behavior and its high fluctuations even during short periods of time. Practical implications: Heat recovery ventilation systems with reducing radon concentration improve indoor air quality and decrease environmental problems with energy savings. Social implications: Using balanced heat recovery ventilation can have benefits from the viewpoint of environmental impacts and household economy. Originality/value: Employment of a heat recovery unit to control indoor radon level is a new usage of this technology which along with energy savings can improve sustainable development.

  • 11.
    Akbari, Keramatollah
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Öman, Robert
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Impacts of heat recovery ventilators on energy savings and indoor radon in a Swedish detached house2013Ingår i: WSEAS Transactions on Environment and Development, ISSN 1790-5079, Vol. 9, nr 1, s. 24-34Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Heat recovery ventilation systems, because of reducing ventilation loss through recovered exhaust air, can play a good role in the effectiveness of ventilation to reduce energy use. In this paper, the impact of a heat recovery ventilator (HRV) on the energy use and indoor radon in residential buildings is investigated. This paper describes the effects of a heat recovery ventilation system on energy consumption in a detached house in Stockholm, Sweden. The performance of the heat recovery ventilation system is examined with respect to radon mitigation and energy saving by measuring the radon concentration and analyzing the life cycle cost of a heat exchanger unit. In this study, a multizone model of a detached house is developed in IDA Indoor Climate and Energy (IDA ICE 4.0). The model is validated using measurements regarding use of energy for heating, ventilation and whole energy use. The results of the measurements and dynamic simulation showed that heat recovery ventilation system 74% energy savings of the ventilation loss, amounted about 30 kWh.m-2 per year. Life cycle cost analysis used for assessing total costs and the result showed that using this system is quite cost-effective and investment would payback during 12 years.

  • 12.
    Akbari, Keramatollah
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Öman, Robert
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Radon Mitigation using Heat Recovery Ventilation system in a Swedish Detached House2013Ingår i: WSEAS Transactions on Environment and Development, ISSN 1790-5079, Vol. 8, nr 3, s. 73-82Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Balanced ventilation with heat recovery has strong effects on radon mitigation and energy saving in residential buildings. This new technology enables improvement of both indoor air quality and energy efficiency without sacrificing either. Reducing radon by means of forced ventilation requires an increase in outdoor supplied air (i.e. ventilation rate), which in turn can increase energy use. Energy losses in ventilation systems are inevitable, but new technologies such as heat recovery systems make it possible to recover most of this ventilation heat loss. Heat recovery ventilation systems, which recover energy from exhaust air, can significantly reduce ventilation losses, and balancing the indoor air pressure plays a positive role in the effectiveness of ventilation to reduce and mitigate radon levels and control indoor air quality. This paper describes a case study which considers the effects of a heat recovery ventilation system on the radon concentration and energy consumption in a detached house in Stockholm, Sweden. The performance of the heat recovery ventilation system is examined with respect to radon mitigation and energy saving by measuring the radon concentration and analyzing the life cycle cost in winter. The results of the measurements and dynamic simulation showed that a heat recovery ventilation system was able to reduce the radon level from around 600 Bq.m-3 to below 100 Bq.m-3 and reduce energy loss from ventilation by 80%, equivalent to around 3500 kWh per year. The results of life cycle cost analysis used to assess total costs showed that this system is cost-effective and investment would pay for itself in 12 years. It should be noted that this saving is a representative sample, and that actual savings would be influenced by a large number of factors. IDA 4.0 Indoor Climate and Energy software was used to perform the dynamic simulations.

1 - 12 av 12
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf