The document provides a critical analysis of the research paper "Summer-performance of inclined roof solar chimney for natural ventilation" by Mathur et al. It summarizes the paper's investigation of how inclination angle affects the performance of a solar chimney in providing natural ventilation. The analysis finds that while the paper provided useful data on ventilation rates for chimneys at various angles, it did not fully justify its conclusion that a 45 degree angle provides a 10% improvement over other angles. It also did not sufficiently discuss opportunities for further research, such as investigating angles between 45 and 60 degrees. Overall, the document provides a detailed review and analysis of the research paper but identifies some limitations in its conclusions and discussion of future work.

1. RESEARCH METHODS MODULE
COURSEWORK ASSIGNMENT A: OTHER PEOPLE’S RESEARCH
ROBERT ATHERTON
JANUARY 2008
1.0 INTRODUCTION
This report examines a research paper “Summer-performance of inclined roof solar chimney for
natural ventilation” (1) by authors Mathur, J., Mathur, S. & Anupma to determine the contribution
the paper has made to human knowledge and the methods used to reach the conclusions.
The report aims to critically analyze the research article into its aims, how the data has been
processed, what has led to this research paper, the current knowledge known and what the research
paper has possibly missed.
Sections referenced 2.2 – 2.7 analyze the individual sections of the research article to determine the
extent of research and what other information would have been useful for the article.
2.0 SUMMARY OF PAPER
The research paper (1) examines performance of an inclined solar chimney that provides natural
ventilation and how the height and angle of the chimney maximises the effect of natural ventilation.
The study was carried out in using theoretical and experimental investigations for a simulation of a
Roof Solar Chimney (RSC) in Jaipur (India) on a latitude of 27o north. The paper is of interest as the
equations and methods used can be applied to other parts of the world based on the local climate and
sun path to determine the optimum angle of a RSC to maximise natural ventilation.
The result of the research determined that 45o was the best angle in Jaipur for the incline angle of the
RSC to balance the stack height and the exposure to solar heating.
2.1 AUTHORS
The authors, Mathur et al. (1) were from the Malaviya National Institute of Technology, Jaipur, 302
017, India, and so it would appear to be a natural choice to base the model in this location to back up
the data with the “Experimental Validation” (1)
It is notable that Mathur et al. (1) have also worked with Bansal N.K. (Author of article reference (9)),
on “Experimental investigations on solar chimney for room ventilation” (10) & “Modeling of window-
sized solar chimneys for ventilation” (11)
2.2 INTRODUCTION COMMENTS
The introduction summarises that the common solar chimney has a vertical absorber which
maximises the sun in the winter, when it is at a lower altitude, but in the summer when more
ventilation is required to assist in cooling, the vertical absorber cannot absorb much of the high
altitude sun. The investigations are set during the summer months and are aimed at “geographical
locations like India.” (1)
The introduction also refers to four separate studies. The information presented is almost a direct
extraction of information from the abstracts of the four papers. The summary of these articles leads
the reader to understand the current extent of knowledge in this field by extracting sections of other
research authors abstracts.
The references to Barozzi et al. (4) and Bansal et al. (5) are almost word for word extraction from the
abstract. There is no elaboration on the evidence obtained from this article. Bansal’s abstract (5) looks
at different sizes of openings together with different co-efficient and ambient and solar temperatures.
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2. All of which are utilised in this report. This report was unable to view the full article text and
references.
The next reference, Aboulnaga et al. (6) is again, an altered summary of the abstract of the article.
However, some of the information contained within that abstract is from another article, but by the
same author.
Chen et al. (7) summarises the experiment of a RSC with uniform heat flux which is effectively what a
solar absorber provides. Chen et al. (7) summarises experiments with a 45o inclined RSC of similar
proportions and its advantages over vertical solar chimneys.
The author could have made more effort to compile the conclusions of these research articles to
provide a clearer statement of the current knowledge in this field. However, the introduction provides
a clear intention of the purpose of the research.
2.3 APPROACH FOR MATHEMATICAL MODELLING
Mathur et al (1) have used mathematical equations to assess the performance of the different incline
RSC. This is the theoretical method of assessment which is supported by experimental validation.
The date chosen was 21 June between 10am and 5pm. It would have been interesting data to have to
sun positions on an hourly basis to determine the relationship of the sun to the chimney. Looking
online (3), the south sun was at its highest at 12:18pm at an altitude of 86.6 degrees. Yet this is when
the mass flow rate decreased, and there is no conclusion as to why this happened, and possible
alterations to improve this.
However figure 3 represents the solar radiation at different times with different tilt angles. This is a
useful chart, but the author’s do not make reference to where this information was obtained and
whether this was validated in the experiment.
2.4 EXPERIMENTAL VALIDATION
The Experimental validation provides useful support for the equations, but there is some confusion
over the chimney and its relationship to the mathematical model as the dimensions clearly differed
and specified the chimney was the full width of the room and with a wider opening.
Table 2 then confirms the variables used to compare the mathematical model and validation exercise.
But some of these results have significant differences, such as the flow velocity with up to 20%
differences in the results. The temperature comparisons are also slightly misleading. Displayed in
Kelvin, the differences between them seems minimal, but converted to degrees Centigrade, there are
differences of the temperature of the absorber wall of 14%. But the statement in “Results and
discussions” states they show “a good agreement” (1).
The table also states the values are from “four different observation sets” (1). These observation sets
are not described in this section, but is assumed to be an average of data taken. Further details on
the experimental validation should be added to substantiate its inclusion in this research article.
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3. 2.5 RESULTS AND DISCUSSIONS
The author clearly likes the idea of a 45o inclined RSC as it balances the optimum solar exposure
(horizontal) with the optimum ventilation flow (vertical). 30o and 60o inclines to demonstrate the
effectiveness of each scenario with different areas of openings.
There are some useful graphs illustrating the performance of the different inclines and opening areas
and shows the 45o incline RSC having the best performance over the steeper and shallower
alternatives demonstrated in figure 2. The peak ventilation flow rate occurs at midday and reduces
after that. The 60o incline RSC actually starts recover its mass flow rate at about 14:30 compared with
o o
the 30 and 60 incline RSC, but Figure 2 finishes at 16:00 although data was taken until 17:00.
Mathur et al. (1) does not expand on this pattern that that may have led to alternative results.
The article then goes on to confirm that the results show the 45o inclined RSC produces the optimum
results because it has a “balance between the two effects” (1) of solar radiation exposure together
with the height of the stack. The 30o incline RSC captures more solar radiation but a reduction of
o
height does not allow air flow to increase, whereas the 60 RSC does the opposite.
2.6 CONCLUSIONS
Referring to figure 2 (1), the charts show there is a consistent improved mass flow rate for the 45o
incline RSC. The conclusions say the improvement is “about 10%” (1). This improvement figure is not
justified in the report. Referring to figure 2(1) and scaling off the graphs, say on the bottom graph
where d=0.3m and z=0.3m, at 12:00pm, the 60o inclination has a mass flow rate of 180Kg/hr, whereas
the 45o inclination has a mass flow rate of 190Kg/hr. This provides a 5.3% improvement and this was
best case. So to add the results up, particularly with the 60o inclination recovering after 14:30, the
results do not achieve 10% improvement. This was the basis of the conclusion for the 45o incline RSC
performance over the 30o and 60o incline RSC.
2.7 ABSTRACT
Therefore, the results of a 10% improvement would need backing up with conclusive data. However,
the abstract summarizes the data well enough and allows the reader to obtain the basic data to allow
them to consider the incline angle of an RSC when designing similar systems.
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4. 3.0 CONCLUSION OF THIS REPORT
The report is effective in highlighting inclined RSC and the performance of different angles of
inclination,
and although it relates to Jaipur, India, it also refers to optimum angles for other latitudes. The paper
contained useful data and charts, but Mathur et al. (1) does not justify where the 10% improvement of
the
45o incline RSC is from. This was crucial as it was the basis of the abstract. And the introduction
which
was aimed at summarizing the current extent of knowledge was directly extracted from other research
paper abstracts. It was difficult to relate the data from the introduction to the research data and the
eventual outcome.
Mathur et al. (1) could have looked at further options. From the results of figure 2, and recovery of the
60o incline RSC in the afternoon, Mathur et al. (1) could have further investigated the following items:
o o
1. Alternative angles of inclination, particularly between 45 and 60
2. Combination of different angle RSC to take advantage of different sun positions.
3. Change orientation to improve air flow in the afternoon.
Opportunities for further expansion on the results obtained were missed but Mathur et al. (1)
succeeded in highlighting the issue of angle of inclination of the RSC that will assist future
researchers and consultants in the future.
However, there is a more recent paper with an almost identical research topic titled “Modeling of the
optimum tilt of a solar chimney for maximum air flow” (9), which deals with very similar issues, but in
more detail, but is actually developed to look at “A composite engineering model that estimates the tilt
of a solar chimney that yields the largest natural air flow through it” (9). This would be a more useful
topic to conclude with and assist designers around the world in benefiting from this research. The
above paper used some of the same references as the topic paper including (5) (7) (8) (12). It is
interesting that this paper (1) was not referred to by Sakonidou E.P et al. (9).
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5. 4.0 REFERENCES
(1) Mathur, J., Mathur, S., Anupma, (10 Jan 2006) Summer-performance of inclined roof solar
chimney for natural ventilation, Published in Energy and Buildings, p, 1156-1163.
(2) Current local time in Jaipur (28 January 2008)
http://www.timeanddate.com/worldclock/city.html?n=516
(3) Sun-rise data for Jaipur (taken from 21 June 2004)
http://www.timeanddate.com/worldclock/astronomy.html?n=516&month=6&year=2004&obj=s
un&afl=-11&day=1
(4) Barozzi G.S., Imbabi M.S.E., Nobile E., Sousa A.C.M., (1992) Physical and numerical
modelling of a solar chimney-based ventilation system for buildings, Building and
Environment 27 (4) 433–445.
(5) Bansal N.K., Mathur R., Bhandari M.S., Solar chimney for enhanced stack ventilation,
Building and Environment 28 (1993) 373–377.
(6) Aboulnaga M.M., Abdrabboh S.N., (2000) Improving night ventilation into lowrise building in
hot-arid climates exploring a combined wall-solar chimney, Renewable Energy 19 47–54.
(7) Chen Z.D., Bandopadhayaya P., Halldorssonb J., Byrjalsenb C., Heiselbergb P., Lic Y.,
(2003) An experimental investigation of a solar chimney model with uniform wall heat Flux,
Building and Environment 38 893–906.
(8) Duffie J.A., Beckmann W., (1980) Solar Engineering of Thermal Processes, Wiley
Interscience, New York.
(9) Sakonidou E.P., Karapantsios T.D., Balouktsis A.I., Chassapis D. (2007) Modeling of the
optimum tilt of a solar chimney for maximum air flow, Solar Energy Volume 82, issue 1, pages
80-94
(10)Mathur, J., Bansal N.K., Mathur S., Jain M. and Anupma (2006) experimental investigations
on solar chimney for room ventilation, Solar Energy Volume 80, issue 8, pages 927-935
(11)Mathur, J., Bansal N.K., Mathur S., Jain M (2005) Modeling of window-sized solar chimneys
for ventilation, Building and Environment, Volume 40, Issue 10, pages 1302-1308.
(12)K.S. Ong, C.C. Chow, (2003) Performance of solar chimney, Solar Energy 74, 1–17.
Total Words: 1994
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