VENTILATION OF THE TOMBS OF THE VALLEY OF KINGS, LUXOR AND THE PYRAMID OF GIZA

Transcription

1 VENTILATION OF THE TOMBS OF THE VALLEY OF KINGS, LUXOR AND THE PYRAMID OF GIZA Essam E. Khalil Fellow ESME, ASME, Member ASHRAE, Associate Fellow AIAA Professor of Cairo University, Faculty of Engineering, Egypt ABSTRACT Airflow characteristics in ventilated and air-conditioned spaces play an important role to attain comfort and hygiene conditions. This paper utilizes a 3D Computational Fluid Dynamics (CFD) model to assess the airflow characteristics in ventilated and air-conditioned archeological tombs of Egyptian Kings in the Valley of the Kings in Luxor, Egypt. It is found that the optimum airside design system can be attained, if the airflow is directed to pass all the enclosure areas before the extraction with careful selection of near wall velocities to avoid any wear or aberration of the tomb-wall paintings. The mode of evaluation should assess the airflow characteristics in any tomb passage according to its position in the enclosure and the thermal pattern and air quality. The airside design and internal obstacles are the focus of the present work. The free air supply and mechanically extracted ducted air play an important role in the main flow pattern and the creation of main recirculation zones. The internal obstacles can offend the airflow pattern by different ways, such as, by increasing the recirculation zones or by deflecting the main airflow pattern. 1. INTRODUCTION To design an optimum HVAC airside system that provides comfort and air quality in the air-conditioned spaces with efficient energy consumption is a great challenge. Air conditioning can be identified as the conditioning of the air to maintain specific conditions of temperature, humidity, and dust level inside an enclosed space. The levels of the air conditions to be maintained are dictated by the local environment, type and number of visitors and required climate and the required visitors comfort and property reservation. 1,2 For the present work, following other earlier similar work 3-5, a numerical study is carried out to define the optimum airside design of the tombs air ventilation and conditioning systems, which provides the optimum comfort and healthy conditions with optimum energy utilization. The present paper introduces a description of the computational solver and its validation with steady state results of the previous properly related literatures. Basically, airside design types are considered here for the tomb passage of King Ramsis VII, including different visitors (obstacles) alternative positioning to introduce the capability of the design to provide the optimum flow and thermal regimes characteristics. The primary objective of the present work is to assess the airflow characteristics, thermal pattern and energy consumption in the different tomb ventilation configurations in view of basic known flow characteristics. The paper ends with a brief discussion and conclusion. 2. METHOD DESCRIPTION Model Equations The program solves the differential equations governing the transport of mass, three momentum components, energy, relative humidity, and the air age in 3D configurations under steady conditions. The different governing partial differential equations are typically expressed in a general form as: x ρ U Φ + Γ x y ρ V Φ Φ x + z + y ρ W Γ Φ = Φ y + Γ z Φ z Φ, eff Φ, eff Φ, eff + S Φ Corresponding Author: address: Khalile1@asme.org

2 Where: ρ = Air density, kg/m 3 Φ = Dependent variable. S Φ = Source term of Φ. U, V, W = Velocity vectors. Γ Φ,eff = Effective diffusion coefficient. The effective diffusion coefficients and source terms for the various differential equations are listed in the following table 1. Table 1: Terms of Partial Differential Equations Φ Γ Φ,eff S Φ Continuity X- U µ eff - P/ x +ρg+ S U momentum Y- V µ eff - P/ y +ρg(1+β t) + S V momentum Z- W µ eff - P/ z +ρg +S W momentum H-equation H µ eff /σ H S H RH-Equation RH µ eff /σ RH S RH τ-age τ µ eff /σ τ ρ equation k-equation k µ eff /σ k G - ρ ε ε-equation ε µ eff /σ ε C 1 ε G/k C 2 ρ ε 2 /k µ eff = µ lam + µ t µ t = ρ C µ k 2 / ε G = µ t [2{( U/ x) 2 +( V/ y) 2 +( W/ z) 2 }+( U/ y + V/ x) 2 +( V/ z + W/ y) 2 +( U/ z + W/ x) 2 ] S U = / x(µ eff Φ/ x)+ / y(µ eff Φ/ x)+ / z(µ eff Φ/ x) S V = / x(µ eff Φ/ y)+ / y(µ eff Φ/ y)+ / z(µ eff Φ/ y) S W = / x(µ eff Φ/ z)+ / y(µ eff Φ/ z)+ / z(µ eff Φ/ z) C 1 = 1.44, C 2 = 1.92, C µ = 0.09 σ H = 0.9, σ RH = 0.9, σ τ = 0.9, σ k = 0.9, σ ε = THEBAN CLIMATIZATION CONTROL PROJECT The Egyptian government had set a handsome budget to the complete restoration of the Valley of the Kings that started years ago with the Theban Mapping Project (TMP) that fully documented the valley s tombs in contour forms and engineering as built drawings of the various individual tombs. These engineering data files are already on the Web site created by TMP. The restored toms, more than twenty are usually open for visitors at frequent times that change depending on the time of the day and the relative humidity. Attempts were made to systematically investigate and assess the flow pattern, heat transfer and relative humidity in theses tombs.the present work is a preliminary attempt to investigate one of these tombs; Ramsis VII.This tomb is simple in construction in a single axis as shown here in Figure 1, where the top is the plan and the vertical cross section at the bottom clearly identified three zones. The entrance zone that extended to over 12 m with door locking the second zone that descended with steps down to another door locking the burial zone where the sarcophagus is located. Figure 2 shows a photographic view of the sarcophagus zone and the wall paintings around it. Figure 1: Tomb of Ramsis VII Configuration

3 Figure 2: Ramsis VII Tomb interior Computational Results Over computational cells were used to map the tomb total volume of 618 m 3,.More than 500 iterations were necessary to achieve the convergence criteria of residuals being less than 10-3 in computational time just under three hours,figure 3 shows the computational domain. The two-equation turbulence model yielded poorer results than those of the Large Eddy Simulations which were used here. Figure 3: Computational cell representing ventilation grilles 4. RESULTS AND DISCUSSIONS In peruse of the appropriate ventilation system designs, simulation of actual air flow patterns and heat transfer behavior was carried out with the above computational scheme with simulation of visitors as shown in figures 4 to 9 in the following paragraphs at wall temperature of 295 K. Grid independency test was carried out first for grid sizes of 89746,106213, and as shown in figure 4. The predictions of the local velocities indicated that the two larger grid sizes yielded grid independent results away from the walls.

4 Scaled Velocity Comparison for Different Number of Mesh Volumes 1.2 Scaled Position, ((Y-Ymin)/(Ymax-Ymin) Scaled Velocity, (V/Vmax) Figure 4: Local velocity profiles at different grid sizes The proposed simulated design is to extract air through floor-mounted ports each 1.0x0.15 m at four different locations as shown in Figure 5, with air freely entering the tomb at 310 K. These were conveniently located in the most likely positions where tomb paintings are to be viewed.consider that the air velocity in the tomb should not exceed 0.12 m/s in order not to create any undesired drafts. Figure 5 indicated that this limit is satisfied regarding velocity values. Figure 5: Predicted Velocity vectors distribution at middle plane, m/s. It is very interesting to observe the higher velocities in the middle section of the tomb as a result of the reduction of the void height. The proposed simulated design using extract air through floor-mounted ports at four different locations is shown in Figure 3. Figures 6,7 and 8 show the cross sectional velocity contours at different axial locations

5 Figure 6: Predicted Iso -Velocity contours, m/s, at Y-Z plane at sarcophagus middle Figure 7: Predicted Iso -Velocity contours, m/s, at Y-Z plane at 2 nd zone inlet, Figure 8: Predicted Iso -Velocity contours, m/s, at Y-Z plane at 2 nd zone 0utlet,

6 The isovelocity contours are shown in Figure 7 at Y-Z plane and it indicated low velocities.the corresponding isothermal lines are shown in Figure 9 below for a wall temperature of 295 K. The effect of the fresh incoming hot air of 37 0 C,in summer, was dominant to almost 45% of the tomb length in the core area. Temperatures in winter time generally cools off to nearly 20 0 C as shown in Figure 10. Figure 9: Predicted air temperature distributions at X-Y middle plane, Peak Summer The corresponding air temperature contours at a Y-Z plane in the middle of the sarcophagus are shown here in Figure 11. The uneven distribution is attributed to the unsymmetrical nature of the tomb configuration. Figure 10: Predicted air temperature distributions inside tomb, Lowest Winter

7 Figure 11: Predicted isothermal contours at a plane at sarcophagus middle, Figure 12: Predicted contours of relative humidity The present investigations were extended to predict the local relative humidity in the tombs in order to better judge the best design of the ventilation system that will not cause any adverse effect on the lime-stone wall paintings. It can be seen from figure 12 that the worst locations are at the deadend of the tomb when occupied by 24 vistors distributed in the 30 m plus passage.for further details, reference should be directed to the work of AbdelAziz PYRAMIDS OF GIZA The present work summarizes the activities carried out to investigate the air flow batterns in the Great Pyramid of Giza. Work is still at very early stages. Figure 13 depicts the Pyramid of Giza. The Pyramid belongs to King Khufu, who is also known by the greek name "Cheops," was the son of King Sneferu and Queen Hetpeheres,ht was built: around B.C. Over 2,300,000 blocks of stones were used to build the Pyramid whose base: 13 square acres, 568,500 square feet, or 7 city blocks. The length of each side of the base was originally 754 feet (230 m), but is now 745 feet (227 m) due to the loss of the outer casing stones;its total weight was 6.5 million tons,with average block weigh 2.5 tons, the larger blocks used for the ceiling of the King's Chamber weigh as much as 9 tons.its height was originally 481 feet (146.5 m) tall, but now only 449 feet (137 m); it was made of limestone and granite..

8 Figure 13: Sectional View of the Pyramid of Giza A computational CFD analyses were performed and the computational scheme is shown here in Figure 14 where more than tetrahedral cells were used. Figure 14: Computational grid allocations for the Pyramid of Giza

9 Figure 15: Flow Contours in the Vertical Shaft of the Pyramid of Giza 6. CONCLUDING REMARKS AND RECOMMENDATIONS The main flow pattern of the free supplied air and floor mounted extracts is slightly influenced by the extraction ports locations. For each visitor group location, a corresponding proper airside design is suggested to provide the optimum utilization of the supplied air.the optimum utilization of the air movement to ventilate and reduce temperature can be attained by locating the extraction ports to minimize the recirculation zone and prevent the air short circuits 8,9. Ideally, the optimum airside design system can be attained 10,11&12, if the airflow is directed to pass all the enclosure areas before the extraction. Still all shown predictions clearly indicated the usefulness of floor extracts that do not disturb the archeological value of the tomb and do not install any artificial materials in the tombs.the influence of the recirculation zones on the visitors occupancy zone and also on the fresh supplied air were investigated.optimum airside design system can be attained, if the airflow is directed to pass all the enclosure areas before being extracted. The model of evaluation should assess the airflow characteristics in any enclosure according to its position in the enclosure and the expected number of visitors that may affect the air during its passage to the extract ports ACKNOWLEDGEMENTS The authors would like to acknowledge the technical support of the Supreme Council of Antiquities, ministry of Culture, ARE and the CAPSCO of Cairo University and to Eng.Omar AbdelAziz and Eng.Osama. Thanks are due to Fluent Inc, for their kind perrmision to use their software to carry out part of the investigation.

10 8. REFERENCES [1] ASHRAE Handbook, Fundamentals 2005, ASHRAE, Atlanta, USA. [2] Stoecker, W. F., and Jones, J. W., 1985, Refrigeration and air conditioning, Second Edition, TATA McGraw-Hill Publishing Company LTD., [3] Khalil, E. E., 2000, Computer aided design for comfort in healthy air conditioned spaces, Proceedings of Healthy Buildings 2000, Finland, Vol. 2, Page 461. [4] Kameel, R., 2002, Computer aided design of flow regimes in air-conditioned operating theatres, Ph.D. Thesis work, Cairo University. [5] Cho, Y., Awbi, H. B., and Karimipanah, T., 2002, A comparison between four different ventilation systems, ROOMVENT 2002, [6] Kameel, R., and Khalil, E. E., 2003, Energy efficiency, air quality, and comfort in air-conditioned spaces, DETC2003 / CIE 48255, ASME 2003, Chicago, Illinois USA, [7] Weeks, K., 1999, Theban Mapping Project, AUC, Egypt. [8] Abdel Aziz, O., 2005 Flow Regimes, Thermal And Humidity Patterns In Ventilated Archaeological Tombs, MSc Thesis, Cairo University. [9] Abdel-Aziz, O. and Khalil,E.E.,2005, Modeling Of Indoor Air Quality And Comfort In The Tombs Of Valley Of Kings, 2005 ASME Summer Heat Transfer Conference, Paper HT , July 2005, San Francisco, California, USA. [10] Abdel-Aziz, O. and Khalil, E. E., 2005 Predictions Of Air Flow Patterns And Heat Transfer In The Tombs Of The Valley Of The Kings Proceedings, CLIMA, October 2005, Paper 358. [11] E. E. Khalil, 2006, CFD, A Tool For Optimum Airside System Design Inside Archaeologicaltombs In The Valley Of Kings, Proceedings Climamed 2006, Lyon, November [12] E. E. Khalil, 2006, Preserving The Tombs Of The Pharaohs, ASHRAE Journal, December 2006, Pp [13] E. E. Khalil, 2007, Climatic Control In the Pyramids of Giza Egypt: Comfort, Air Quality, and Energy Utilization. Proceedings Greek Mech.&Elect. Engnineering Conference, Athens, May 2007.