Whole Field Measurement of Temperature and Concentration and Validation of CFD Code for Indoor Climate

   
Project leader: Professor Bahram Moshfegh and Professor Mats Sandberg
PhD student: Shahnaz Amiri
Supported by: University of Gävle and KK-Foundation

KK-Fpundation logga

Background


People spend almost 90% of their time in different indoor surroundings like houses, workplaces, means of transportation etc. It is well known that the indoor climate has a strong influence on our health and comfort. However, to studying and mapping the indoor climate in a large room we have to measure many different quantities with high resolution over the whole room. It is therefore of great importance to be able to map and measure indoor climate within large areas with simple and correct methods in order to optimize and arrange a pleasant and comfortable environment. But mapping and measurements of e.g. air temperatures and air velocities within a large area simultaneously is with present technology (point measuring technique) very time-consuming and gives insufficient information as well.  

Consequently there is a big demand/need of modernization and development of new and better presentation techniques.  

Objective


The objective of this project is to prepare a way for an easy, legible and powerful presentation of indoor climate data (air temperatures, air velocities and air pollution concentrations) with help of modern information technology. The project contain development of new and better measurement methods (whole field measuring technique) and simulation models based on Computational Fluid Dynamics, CFD, that reflect the indoor climate and produce digital “pictures".  
Physical variableWhole-field measuring methods
Air temperatureInfrared camera and a measuring screen
3-d velocity fieldParticle streak velocimetry based on stereo photogrammetry
Contaminant concentrationsAbsorption tomography (Compare brain imaging in medicine)
The digital information received from measurements and simulations can then underlie display and presentation of indoor environment in three-dimensional virtual reality rooms. The information can easily be transmitted worldwide via Internet. The proposed presentation technique provides the possibility for the “people" to “walk" through the rooms and “feel" the indoor climate.

Progress so far

Infrared thermography


The new high definition hand-held digital IR cameras have given opportunities to develop a new method for measuring temperatures within a large area. With this method the air temperature is measured indirectly by using infrared thermography and a measuring screen.  

Both experiments and analytical calculations have been performed in order to improve and optimize this new whole-field measuring technique. The experimental part of the investigation has lead to a conference paper to ROOMVENT 2000, see Cehlin et al (2000a). The findings of the presented paper are that this measurement method is very useful for illustration and visualization of the distribution of temperature in a room with displacement ventilation (see figure 1). The IR camera measures the absolute temperature of the screen with very high accuracy. However, the results show that there is a difference between the temperatures of the screen and the air temperature in regions near the diffuser and the floor. The source of error seems to originate from radiation from the surrounding objects and surfaces.  

Temperature picture taken by IR camera
This developed measuring method has recently been used in an indoor climate investigation in a factory hall at Volvo, Eskilstuna. The work has been published as a Working paper, see Cehlin et al (2000b).

Computed tomography


Computed tomography is best known for its use in medicine, in which cross sections of a human body are reconstructed from a large number of x-ray attenuation measurements through out the body section, see figure 2. This technique can also be applied to the environment. Rather than sending radiation at many angles through a body to view organs, a network of optical beams is sent through air at many angles to reconstruct chemical concentrations.
Computed tomography in brain-scanning
Under the past year I have performed theoretical literature studies for development of a whole-field measuring method for concentration-measurements of a plume, based on computed tomography. Different kinds of theories, geometrical arrangements, equipment and mathematical algorithms have been reviewed. The information will underlie continued studies and experiments under the year of 2000.

Planned Work - 2001


The results from the analytical study regarding the method for measuring air temperatures will be presented in an article published probably in Energy and Building under the year 2001.  

Also a three-dimensional Computational Fluid Dynamics (CFD) model will be built up to analyse the performance of the method under different conditions. Especially the screen temperature relative to the local air temperature will be carefully analysed. The convective heat transfer coefficient along the screen will also be studied. The convective heat transfer coefficient along the screen will also be studied. An abstract is submitted for the present study to CMEM 2001, 4-6 June 2001, Alicante, Spain.  

Under the year of 2001 a Licentiate Thesis is intended to be presented. In this thesis the research regarding computed tomography will also be included.

Publications

  • Cehlin, M., Moshfegh, B. and Sandberg, M., (2000a) “Visualization and measuring of air temperatures based on infrared thermography", ROOMVENT 2000, Reading, England.
  • Linden, E. Céhlin, M. and M. Sandberg, (2000b). “Temperature and Velocity Measurements on a Diffuser for Displacement Ventilation with Whole-Field Methods".Proceedings of The 7th International Conference on Air Distribution in Rooms, ROOMVENT 2000.
  • Cehlin, M., Moshfegh, B. and Stymne, H., (2000c) “Kartläggning av inneklimatparametrar i Volvo Eskilstuna", Working Paper No 10, University of Gävle
Publicerad av: Liselotte Laurila Sidansvarig: Gunilla Mårtensson Sidan uppdaterades: 2013-10-17
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