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ase study

FD application to optimise the ventilation strategy of Senate Room at Palazzoadama in Turin (Italy)

tefano Paolo Corgnati ∗, Marco Perinoruppo TEBE, Dipartimento di Energia, Politecnico di Torino - Corso Duca degli Abruzzi, 24, Torino, Italy

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rticle history:eceived 12 January 2010ccepted 20 February 2012vailable online xxx

a b s t r a c t

Over the last years, there was an increasing interest in keeping suitable microclimatic conditions forthe preservation of artefacts: the artefacts preservation requirements may diverge from those of themuseums visitors, willing to enjoy the works of art in a situation of psycho-physical wellness. TheHVAC designers and engineers will have then to cooperate closely with the curator, in order to define a

eywords:useum

FDndoor environment

compromise between conflicting environmental performance requirements. In particular at the stage ofair-conditioning system design or retrofit, it is extremely important to carry out a series of preliminaryanalysis to evaluate and monitor the existing environmental conditions and to anticipatory simulate andpredict the post-intervention conditions. To this aim, advanced fluid-dynamic investigation tools (Com-putational Fluid Dynamic [CFD] techniques) enable to deal with the specificity of such topics and providea useful decision-making support.

© 2012 Elsevier Masson SAS. All rights reserved.

. Research aim

The present work aims at showing the potential of CFD tools toredict air flow paths and thermo-hygrometric fields in museum

ndoor environments.In particular, a large exhibition area is studied in order to identify

n alternative solution for more suitable ventilation strategy andicroclimatic conditions in the environment, without changing the

osition of the air inflow devices. Since the aim of the research waso optimize the ventilation strategy and the air distribution, onlyhermal and flow fields have been analysed and compared, and theffectiveness of the proposed improved solution has been demon-trated. Hygrometric fields were not investigated in this specifictudy.

. Introduction

Over the last years, public opinion and institutions have shownn increasing interest in keeping Suitable microclimatic conditionsor the preservation of works of art and artefacts in museums,xhibitions, storage areas, and archives [1,2]. In fact, the exhibi-

Please cite this article in press as: S.P. Corgnati, M. Perino, CFD applicatMadama in Turin (Italy), Journal of Cultural Heritage (2012), doi:10.10

ion areas can be considered as the heart of a museum, the placehere objects acquire a cultural value. In such areas, the artefactsreservation requirements may diverge from those of the visitors,

∗ Corresponding author. Tel.: +39 011 5644507.E-mail address: stefano.corgnati@polito.it (S.P. Corgnati).

296-2074/$ – see front matter © 2012 Elsevier Masson SAS. All rights reserved.oi:10.1016/j.culher.2012.02.007

willing to enjoy the works of art in a situation of psycho-physicalwellness [3]. The HVAC designers and engineers will have then tocooperate closely with the conservator and the exhibition curator,in order to define a compromise between conflicting environmentalperformance requirements [4].

Continuous monitoring of the environmental parameters (tem-perature, relative humidity, air speed, lighting, air pollutants, etc.)ensure conservators, curators, restorers and lenders that the envi-ronmental conditions, under which the works of art are keptduring the exhibitions, are continuously supervised and that anearly detection of critical situations is possible [5,6]. This helps topromptly detect and prevent any deterioration processes [7]. Suchprecautions lead to an actual programme of preventive control andoptimal microclimatic conditions maintenance [8].

A correct microclimate control for artefacts preservation doesnot necessarily requires the adoption of sophisticated installationsand complex environmental control systems. Satisfactory achieve-ments may be obtained through a preliminary and careful analysisof the actual environmental dynamics, firstly with a special empha-sis to the “free running”, passive, attitude of the building and thenwith the investigation of the performance of the existing equip-ments. Such investigation, in fact, allows to define, before anystructural intervention, the compatibility between the climate con-trol features and the preservation requirements [9]. This approach

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has become more and more well-liked among the experts [10].During the design and implementation of the exhibition set-

ting, in particular at the stage of air-conditioning system designor requalification, it is extremely important to carry out a series

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f preliminary analysis, by using suitable tools, to evaluate andonitor the existing environmental conditions and to anticipatory

imulate and predict the post-intervention conditions [11]. Inarticular, the estimate, in “predictive” terms, of the microclimaticarameters and of their space distribution is becoming essential

n order to define the compatibility of the environment with theaintenance of the desired conservation conditions [10,12].In this way, any critical conditions that could eventually arise

an be detected before the installation refurbishment and/or con-truction will start. The necessary adaptations and modificationsan then be implemented at an early design phase.

To this aim, advanced fluid-dynamic investigation tools (Com-utational Fluid Dynamic [CFD] techniques) enable to deal withhe specificity of such topics and provide a useful decision-makingupport [13].

In particular, CFD techniques allow to study large confinedpaces, where it is difficult to predict the indoor air flows andhermo-hygrometric fields by means of simplified models or mea-urements (IEA ECBCS – Annex 26 “energy efficient ventilation ofarge enclosures”) [14].

Thanks to their features, CFD software, originally used only forcientific research, have become, in recent years, a design supportool used by professional engineers when an in-depth knowledgef indoor air flow paths and pollutants distribution is required.

. Methods

In CFD models the equations of conservation for mass, momen-um (expressed by the Navier–Stokes equations), energy andhemical species, together with the turbulence models [15,16], areritten and solved. In particular, the partial differential equations

uling the system are discretized in terms of finite differences andolved in a given number of points of a grid overlapped to the geo-etrical domain. The discretization approach adopted for the air

istribution analysis is typically that of the finite volume method.lternatively, the finite element method is used [16,17].

In this study, a large exhibition area was studied in order to iden-ify an optimal solution for a ventilation strategy able to provide

Please cite this article in press as: S.P. Corgnati, M. Perino, CFD applicatMadama in Turin (Italy), Journal of Cultural Heritage (2012), doi:10.10

etter microclimatic conditions in the environment. Constructiononstraints were such that it was not possible to change the positionf the air inlet devices and the only applicable improvement waso change shape and direction of the primary air supply jets. The

Fig. 2. Air inflow devices position: previous solution and

Fig. 1. Palazzo Madama (Turin) view.

research activity has consisted of a detailed analysis of the total airflow paths and velocity/temperature fields inside the room, duringboth heating and cooling operating conditions. Different solutionshave been tested to optimize the primary air distribution. Indoor airflows and the thermal fields were simulated and the resulting envi-ronmental conditions were compared. The analysed configurationshave been identified in order to improve the thermo-fluid-dynamicbehaviour by modifying as less as possible the existing configura-tion. The effectiveness of the proposed optimal solution was, finally,proved.

3.1. The case study

The fluid-dynamic simulations were aimed at analysing the airdistribution and the environmental conditions in the Senate Room,a large-sized exhibition space in Palazzo Madama – Turin (Italy)(Fig. 1).

This room is parallelepiped-shaped, with a base of18.6 m × 23.5 m and a height of 19 m.

The HVAC system consists of a primary air system coupledto fan-coils. The primary air is supplied thorough seven air inletdevices located near the ceiling, just above a cornice, with an

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inclined flow direction, as shown in Fig. 2a and b.Moreover, inside the room, there are 12 fan-coils homogenously

distributed on the sidewalls and located at floor level, which pro-vide both heating and cooling.

ameliorative solution (plan view/vertical section).

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Table 1Boundary conditions used for the Senate Room simulations (set-point values refersto nominal design values).

Air flow rate and air speedPrimary air Speed = 1.9 m/s Flow rate = XXX m3/hFan-coils Speed = XX m/s Flow rate = 300 m3/h

TemperatureSupply air (primary air) Winter: 20 ◦C Summer: 20 ◦CFan-coils Winter: 32 ◦C Summer: 20 ◦CSurface (envelopecomponents)

Winter: 19 ◦C Summer: 26 ◦C

Fig. 3. Senate Room: model.

.2. CFD Model

The Senate Room was modelled as a parallelepiped enclosureith a size of L(x) = 18.6 m, W(y) = 23.5 m, H(z) = 19 m.

Compared to the actual shape of the room, which is slightlyrapezoidal (see Fig. 2), the model adopts an equivalent rectangularhaped plan. Fig. 3 shows the geometrical model of the room withhe location of the air inlet openings and fan-coils.

The geometrical domain has, then, be discretized subdivid-ng the sides of the parallelepiped as follows: L(x) = 54 segments,

(y) = 49 segments, H(z) = 33 segments; this corresponds to a com-utational grid of over 87,000 structured cells.

The air inlet devices and the fan-coils have been positioned inhe same points as they are in the actual design. They were sim-lated by means of fixed air velocity boundary conditions (that ispecifying air speed, air flow direction and local turbulence quan-ities - turbulence intensity and equivalent length of turbulenceor the specific inlet device). Primary air was extracted, through

Please cite this article in press as: S.P. Corgnati, M. Perino, CFD applicatMadama in Turin (Italy), Journal of Cultural Heritage (2012), doi:10.10

ectangular openings at the floor level (Fig. 3).For both the primary air and the recirculated air from the fan-

oils, the boundary conditions were chosen so as to provide in theodel the same value of the actual air flow rate and air speed of

Fig. 4. Original design solution: vectors on a horizontal plane

Set-point values (indoorenvironment)

Winter: 20 ◦C Summer: 25 ◦C

the Senate room (this meant to create a model in which the size ofthe air inlet devices match that of the actual design. Therefore, theboundary conditions refer to the design specifications).

The temperature of the primary air introduced through theair inlet devices and the fan-coils, in both winter and summeroperating modes, and the surface temperatures of the buildingenvelope components (identified in the floor, ceiling and walls)were assumed equal to the nominal design values. The internalheat gains during the summer period have been modelled as anuniformly distributed load over the floor (fixed heat flux boundaryconditions).

The resulting total thermal loads (corresponding to about33 W/m2 for heating and 77 W/m2 for cooling) are balanced by thethermal powers generated by the mixed system “primary air andfan-coils”.

Table 1 resumes the boundary conditions used for the numericalsimulations.

4. Results

Some of the simulation results are graphically resumed inFigs. 4–6, where the streaklines (showing the main air flow path

ion to optimise the ventilation strategy of Senate Room at Palazzo16/j.culher.2012.02.007

inside the Senate Room), the velocity fields and the temperaturefields are shown. In particular, flow and air temperature fields areplotted over a plane located at a representative height of 1.8 mabove floor level.

at air inlet devices height in heating operation mode.

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For the sake of brevity, only results related to the original

Please cite this article in press as: S.P. Corgnati, M. Perino, CFD applicatMadama in Turin (Italy), Journal of Cultural Heritage (2012), doi:10.10

design) and the optimized (final, after retrofit) configurations arenalysed in the paper. The sensitivity analysis, from which the opti-al configuration has been identified, was based on a series of

ig. 5. Simulation results related to the original solution: streaklines (a: grey arrow = maiode (velocity and temperature fields are represented on a horizontal plane at 1.8 m abo

PRESSural Heritage xxx (2012) xxx–xxx

simulations performed by using the same ventilation system but

ion to optimise the ventilation strategy of Senate Room at Palazzo16/j.culher.2012.02.007

by changing the direction (angle and tilt) of the inlet air jets.For the design configuration (Fig. 5), the velocity and tem-

perature fields reveal a non-uniform spatial distribution of the

n air path), velocity field (b), temperature field (c), in heating and cooling operationve floor).

ARTICLE IN PRESSG ModelCULHER-2600; No. of Pages 8

S.P. Corgnati, M. Perino / Journal of Cultural Heritage xxx (2012) xxx–xxx 5

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nvironmental parameters during both the heating and coolingperations. In particular, the flow field shown in Fig. 4 (velocityectors are sketched) and streaklines plotted in Fig. 5 highlight thathe supply air flow does not mix efficiently with the indoor air. The

ain air flow path, in fact, is confined in a small part of the room,ear the lateral and front walls. The primary air jets reach the upperart of the opposite wall (Fig. 5a) and then flow downwards, influ-ncing the occupied zone only in a relatively small area located athe opposite side of the main entrance. This flow structure does notllow for an optimal exploitation of the ventilation air. Flow short-uts between supply and exhaust air arise and a stagnation zone,haracterized by low velocities, forms in the central part of the roomFig. 5b, c). The phenomenon is particularly stressed for coolingsummer) conditions where a zone with higher air temperatures islso highlighted.

The fact that the air distribution performance is quite poor,

Please cite this article in press as: S.P. Corgnati, M. Perino, CFD applicatMadama in Turin (Italy), Journal of Cultural Heritage (2012), doi:10.10

ill negatively influence the possibility of properly controlling theelative humidity, pollutant concentration and temperature levelsnside the hall and of achieving optimal environmental conditionsor the conservation.

inued ).

Following these preliminary simulation results (performedbefore the building retrofit), many different configurations wereanalysed and tested, aimed at solving the air distribution problems.

The final proposed ventilation system set-up allowed to findan improved solution for both the heating and cooling operationmodes. Simulation results related to this optimized configurationare shown in Fig. 6.

It can be seen that, now, the primary air jets behaviour is similarto a “free air jet”, with the primary air flow falling “as a cascade” intothe occupied zone (Fig. 6a). The degree of mixing is far higher thanin the original solution and this leads to a better spatial uniformityof the air velocity and temperature. Both the flow and temper-ature fields (Fig. 6b, c) reveal a reasonable symmetry along thelongitudinal axis, without any relevant stagnation zone. The envi-ronmental parameters, despite the significant volume and heightof the room, are sufficiently uniform. Therefore, such flow con-

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figuration will allow a better control of the temperature, relativehumidity and pollutant transport and deposit within the entirespace occupied by the exhibition, in both summer and winterconfigurations.

Please cite this article in press as: S.P. Corgnati, M. Perino, CFD application to optimise the ventilation strategy of Senate Room at PalazzoMadama in Turin (Italy), Journal of Cultural Heritage (2012), doi:10.1016/j.culher.2012.02.007

ARTICLE IN PRESSG ModelCULHER-2600; No. of Pages 8

6 S.P. Corgnati, M. Perino / Journal of Cultural Heritage xxx (2012) xxx–xxx

Fig. 6. Simulation results related to the optimised solution: streaklines (a: grey arrow = main air path), velocity field (b), temperature field (c), in heating and cooling operationmode (velocity and temperature fields are represented on an horizontal plane at 1.8 m above floor).

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. Conclusions

In the present paper, the potentialities of advanced computa-ional tools applied to the theoretical analysis of museum indoornvironments were tested and evaluated.

In particular, CFD techniques were used to examine and predicthe microclimatic characteristics of a case study exhibition hall,ocated inside an historical building in Turin.

The use of CFD software revealed to be particularly suited for theoncept phase of the design of an exhibition space and it’s setting,hen alternative air distribution strategies have to be evaluated

n order to identify the one, which ensures the best microclimateuality. The main steps to follow in a CFD investigation procedurere here summarized:

definition of the geometrical model;

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characterisation of the air flow opening/devices and of the inter-nal gains (heat, pollutants, etc.);definition of the boundary conditions and adoption of a turbu-lence model;

inued ).

• discretization of the calculation domain;• run of the numerical simulation and verification of the numerical

convergence;• analysis of the results (air flow path, velocity fields, thermal fields,

etc.).

As shown by the application to the Senate Room in PalazzoMadama, the results obtained from the numerical thermo-fluid-dynamic simulations allow to overcome potential problems ofnon-uniform and poor environmental control before the construc-tion phase.

In the analyzed case study, the solution to the critical aspectsarising from the original, design configuration was simply achievedby adjusting the direction of the primary air jets entering into theroom. Moreover, the predicted temperature and velocity fields leadto the conclusion that, after implementing the proposed adjust-

ion to optimise the ventilation strategy of Senate Room at Palazzo16/j.culher.2012.02.007

ments on the ventilation system, the large hall will be suitable tohost both temporary or permanent exhibitions.

The presented study did not dealt with relative humidity field,but the uniform air and temperature distribution inside the room

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well mixed ventilation strategy) allow to assume that it will beossible to satisfactorily control the relative humidity. A contin-ous monitoring of the indoor environmental parameters (T andH) has been suggested and will be performed after the ventilationystem renovation.

cknowledgement

The authors wish to thank Fondazione Torino Musei and Munic-pality of Torino for supporting this research.

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