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CLIMA 2010 - PROGRAM BOOK
InvitationDear Participants of Clima 2010 Rehva World Congress,
I would like to “Welcome you to Clima 2010” on behalf of TTMD and Organizing Committee. We have worked with pleasure and excitement to prepare this Congress; starting four and a half years ago.
Now, the day came and we are together with your works and contribution to create “Sustainable Energy Use in Buildings” as the theme of the Congress... I hope you will find the program of this leading international scientific congress very rich, interesting and full of activities; having new information and building new friendships...
The 10th REHVA World Congress has been prepared with the support of our Ambassadors in many countries, with many National and International Associations and also with our sponsers; with our thanks which led to receive high interest and we have received a record level abstracts and participation with papers and posters. We are happy to present this program to give you the chance to value every minute to listen the oral presentations, examine the posters and contribute to the workshops and follow the other activities like Students Competition and the Industrial Forum organized by rehvaclub.
We are grateful for coming from 6 Continents. Having the format to have the venue in a Congress Hotel will enable you to benefit from the Mediterrenean Holiday atmosphare and taste the Turkish Food and enjoy the sea and sand at your free times... Meeting with international friends will be possible for the the exchange of your scientific knowledge and experience as well as discussing the solutions on the new topics.
Our organization team will be ready to make your stay enjoyable and memorible one. Whenever you need, please find one of us; as we will be everywhere...
Wish all the best and fruitful Congress.
Numan SAHIN President of Clima 2010, 10th REHVA World Congress
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CLIMA 2010 - PROGRAM BOOK
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CLIMA 2010 - PROGRAM BOOK
09 MAY 2010 - SUNDAY 16:30-18:00
17:00 R8-TS8-OP03 Comparing Monitoring Results with Energy Performance Calculation: Uncertainty Analysis
Sihem Tasca Guernouti, Myriam Humbert
17:15 R8-TS8-OP04 A Validation of the Quasi-Steady State Building Energy Model by a Dynamic Numerical Analysis Ilaria Ballarini, Alfonso Capozzoli, Vincenzo Corrado
17:30 R8-TS8-OP05 Experimental Analysis and Modeling of the Thermal Performance of Ventilated Roofs Paolo Baggio, Paolo Pancheri, Alessandro Prada, Marco Baratieri, Guido Libardoni
17:45 R8-TS8-OP06 Integrated Energy Simulation for Building and MEP Systems Including Thermal Cascading in Consideration of the Characteristics of Thermal Energy Media Ryota Kuzuki, Makoto Satoh, Shuzo Murakami, Takashi Akimoto, Hisaya Ishino, Kenichi Sasajima, Fumio Nohara, Hiroshi Ninomiya, Yasuhiro Tabata
ROOM 10 WORKSHOP 16 HVAC TEACHERS MEETING Course Directors : Michael Schmidt, Zoltan Magyar
The objective of this workshop is to increase the co-operation between HVAC teachers in the area of common teaching material, student exchange and the contents of the curricula. The workshops offers an opportunity to exchange idea for future needs and development of teaching to serve better the needs of developing HVAC industry.
ROOM 11 WORKSHOP 1 PRESENTATION OF THE GUIDEBOOK FROM REHVA CONCERNING HVAC AIR FILTERS AND FUTURE ACTIONS Course Directors: Ulf Johansson, Jan Gustavsson
The workshop presents the contents of the new REHVA Guidebook on air filters in air handling systems and discusses the need of the future actions in the area of air cleaning and filtering in respect of indoor air quality and energy efficiency of buildings.
09 MAY 2010 - SUNDAY 16:30-18:00 ROOM 7 TECHNICAL SESSION 7 INDOOR ENVIRONMENT-1 Chairpersons: Shin-ichi Tanabe, Edward A Arens
16:30 R7-TS7-OP01 A Study on Measurement of Indoor Environments of an Office Building and Occupant’s Subjective Evaluation Tae Woo Kim, Byeung Hun Son, Won Hwa Hong
16:45 R7-TS7-OP02 Interior Design and Material Emissions Ingrid Senitkova, Tomas Tomcik
17:00 R7-TS7-OP03 Strategy for Good Perceived Air Quality in Sustainable Buildings Henrik N. Knudsen, Pawel Wargocki
17:15 R7-TS7-OP04 A Conceptual Approach to Determine Optimal Indoor Air Quality: A Mixture Experiment Method Godfaurd A John, Derek C Clements Croome, Joe Howe
17:30 R7-TS7-OP05 Simultaneous Measurements of CO2, Radon and Thermal Parameters in a Bank Agency Manuel Gameiro da Silva, José Joaquim Costa, Luis Figueiredo Neves, Alcides Castilho Pereira
17:45 R7-TS7-OP06 Urban Climate Impact on Indoor Environment Quality Adrien Dhalluin, Karim Limam
ROOM 8 TECHNICAL SESSION 8 BUILDING SIMULATION-1 Chairpersons: Vincenzo Corrado, Samir Farid Moujaes
16:30 R8-TS8-OP01 Calculating Heating and Cooling Loads in a Room by Developing a Transient Thermal Simulation Approach Coupled with a Zonal Air Model Ali Kazemipour Papkiadeh, Aziz Azimi, Siamak Kazemzadeh Hannani
16:45 R8-TS8-OP02 Integrated 6R1C Energy Simulation Method – Principles, Verifiacation and Application Piotr Narowski, Maciej Mijakowski, Aleksander Panek, Joanna Rucinska, Jerzy Sowa
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12 MAY 2010 - WEDNESDAY
15:15-17:15
ROOM 1 CLOSING CEREMONY -Selected Student Project Ceremony and Presentation -Selected Poster Ceremony and Presentation -Announcement of the Next Congress
17:15-18:00 FAREWELL COFFEE
INDEX
A. Fahim Ahmed A Medhat 98, 60
Abak Kazım 99
Abdenacer Kaabi 74
Abuhafeetha Maha 32
Acul Hasan 90
Adamovsky Daniel 55
Adnot Jérôme 96
Afjei Thomas 37, 90
Afshari Alireza 62, 93, 33
Ağra Özden 57
Ahached Mohamed 62
Ahmadi G. 54
Ahmed Zebun Nasreen 40
Ahn Taekyung 78
Airaksinen Miimu 11, 100
Akbalık Bayram 30
Akimoto Takashi 62, 75, 100, 15, 64
Akio Onishi 11
Akoua Jean Jacques 73, 12
Akpinar Irem 52
Aksel Haluk 57
Al Emar Wid A 83
Al Mutawa Nawaf K 77
Al Rashidi Khaled E 77
Ala Juusela Mia 70
Alain Rousset 27
Alajmi Ali F 83
Alameddine Zeinab 71
Albert Maik 37
Albieri Michele 57
Ålenius Lars 46
Alexandre Jose Luis C 50, 97, 23, 96
Ali Toudert Fazia 38
Alina Girip 26, 60
Allard Francis 37, 73, 12, 23, 34
Almeida Susana Marta 45
Almesri Issa F. 65
Alsbjer Markus 83
Alucci Marcia Peinado 66
Alvarez Servando 10, 49
Álvarez Domínguez Servando 73
Ampenberger Andreas 46
Andersen Per Arnold 67
Andre Philippe 10, 10, 29, 29, 29, 10
Andújar Rabindranath 38
Angelotti Adriana 38, 72, 77
Anica Ilie 60, 43
Antonescu Nicolae 58, 58
Aradag Selin 43
Arens Edward 44
Ari Seckin 37
Ariaudo Federica 79
Ariya Parisa A 32
Armstrong Peter 19
Arsan Zeynep Durmus 84, 39
Arslan Gökhan 12
Arumägi Endrik 61
Asada Hideo 65
Asadi Ehsan 55
Asano Natsuki 75
Asdrubali Francesco 66
Ashjaee Dr.mehdi 89
Asikainen Vesa 54, 46
Åström Johan 88
Ataer Ercan Ö. 85
Atılgan İbrahim 44, 66
Atmaca Merve 12
Awbi Hazim B. 65
Axell Monica 25, 83, 95
Aydar Emir 70
Azami Ahadollah 98
Azimi Aziz 14
Babiak Jan 9, 39
Baccoli Roberto 30
Bacigalupo Emilio Giuliano 53
Bağbancı Bilal Muhammed 61
Bağbancı Özlem Köprülü 61
Baggio Paolo 90, 15, 39
Baghvand Aysan 98
Bahloul Ali 86, 55
Baker Derek K. 40
Bakhar Ravi 51
Bakirci Kadir 29
Baldassa Paolo 49
Baldinelli Giorgio 66
Baldini Luca 88, 52
Bales Chris 37
Ballarini Ilaria 15
Balta Mustafa Tolga 30
Baltaretu Florin 99
Balvers Jaap 53
Baranowski Andrzej 50, 61
Baratieri Marco 24, 15, 27, 42
Barbosa Juliana Cortez 78
Barna Lajos 96
Başaran Tahsin 28
Başkaya Şenol 44, 66
Basso Luigi 57
Basta Jiri 36
Başyazici Ibrahim Utku 85
Baumann Mihaly 20
Bayer Ozgur 37, 43
Bayraktar Meltem 84
Bayraktar Seyfettin 42
Bayulu Funda 37
Beauregard Sandy 11
Becchio Cristina 23
Beck Wouter 84
Beghein Claudine 23
Beghi Alessandro 57
Bekker Bernard 86
Belarbi Rafik 46
Bellone Tamara 79
Benedetti Cristina 27, 42
Benjamin Boillot 24
Benoît Andlauer 39
Bergsøe Niels Christian 93, 33, 62
Berkland Stephanie 11
Bernard Collignan 33
Bernard Flament 39
Bernier Michel 61
Bertagnolio Stephane 10, 10, 29, 29, 29, 87
Bhattacharya Kishore 28
Bianchi Ana Maria 99
Bianchi Mikael 37
Bienert Sven 20
Biesbroeck Katrien 71
Bilge Mustafa 85
Bilgili Mehmet 52
Bingöl Ekin 26
Bistran Ioan 55
Biwole Pascal Henry 64
Blaszczok Monika 52, 65
Blom Inge 91
Bozic Nejc 76
Boazu Rodica 20
Boelman Elisa 21
Boerstra Atze 53, 76
Bogataj Uroš 76
Bogdan Anna 65, 63, 66
Bogdan Caracaleanu 60
Boian Ioan 77
Bolashikov Zhecho 54
Borderon Julien 50
Borhansadigh Alireza 98
Borodinecs Anatolijs 20, 86
Bossaer Alain 31
Bouaziz Nahla 62
Bouchaala Mourad 42
Bourrelle Julien S 51
Boxem Gert 70, 20, 94
Bozdağ Şaziye 99
Bozonnet Emmanuel 34
Brahmanis Arturs 44
Brand Marek 54
Brata Silviana 55
Breesch Hilde 71
Brito Augusto 59
Brohus Henrik 50
Bronsema Benjamin 10
Broström Tor 61
Brunk Marten F 60
Budiaková Mária 13
Bulinska Anna 43
Bulut Murat 37
Chen Yixing 75, 75
Chiara Sbicego 79
Chikamoto Tomoyuki 75, 100
Chiriac Florea 37, 43
Chludzinska Marta 66
Cho Ga Young 91
Cho Jinkyun 19, 63
Cho Woosuk 63
Choi Jin Tae 74
Chopra Nikhil 53
Chow Tin Tai 13, 96
Christian Bruss 99
Christian Ghiaus 40, 40
Chung Minhee 12
Ciampi Mario 72
Cibej Marko 76
Claesson Johan 21
Clements Croome Derek C 14
Clita Iulian 11, 55
Cocchi Alessandro 58
Cocora Octavia 90
Çolak Levent 90
Colda Iolanda 41, 64, 76, 33, 44
Coll Sergi 38
Comakli Kemal 29
Conrad Ernest 52
Corgnati Stefano P. 42, 79
Corrado Vincenzo 59, 15
Cortés Inés Olmedo 73
Coskun Can 34
Costa Andrea 90
Costa Gaia 26, 38
Costa Jose J. 55, 14
Crutescu Marin 40
Crutescu Ruxandra 40
Culakova Monika 39
Cullin James 61
D Alessandro Daniela 89
D Orazio Annunziata 89
Dai Tongyong 83
Dalal Hari Sankar 31
Dam Peter van 78
Busato Filippo 85, 30
Busnardo Elena 57
Buswell Richard 43
Butala Vincenc 24, 66
Byun Sooyoung 12
Caillet Julien 96
Cakir Ugur 29
Çakır Gökçe 44
Çakmanus Ibrahim 39
Caldare Ioan 49
Calí Davide 60
Çalışkan Sinan 44, 66
Çallı Ümit 90
Calota Razvan 84
Camargo Renata 72
Cambray James T 94
Canha Nuno 45
Cano Cristina 73
Cansevdi Bekir 90
Cantin Richard 50
Cao Bin 77
Cao Guangyu 76, 76, 100
Cao Zhixuan 13, 87
Capozzoli Alfonso 15
Cappelletti Francesca 59, 90, 39
Cappon Francesco 30
Caputo Paola 26, 38
Caram Rosana 72, 91
Carew Paul 86
Carlini Ubaldo 30
Casabó Jordi 38
Cauret Odile 61
Causone Francesco 42, 77
Cecchinato Luca 57
Celik Burcu Cigdem 84
Cha Dong An 74
Chan Apple 96
Chan Hoy Yen 96
Chan Kwoktai 83
Chandrasen Kshitij 34
Chao Christopher 75
Chen Qingyan 72, 72, 75
Dama Alessandro 72
Dang Thong Q 75
Daniels Ole 64
Daşgan Yıldız 99
David Benjamin 49
David Mathieu 79
Davis Adreans 28
De Araújo Victor Almeida 78
De Carli Michele 59, 30, 77, 44, 79
De Carvalho Ricardo Luis Teles 33
De Giuli Valeria 59
De Meester Bram 31
De Paepe Michel 9, 95
De Ridder Fjo 61
De Rossi Luigi 57
De Santoli Livio 20
De Schepper Paul 41
Decorme Regis 70
Deecke Holmer 9
Delahaye Claire 91
Demetriou Dustin 19
Demircioğlu Olgu 57
Demiriz Mete 30
Deng Jie 74
Derome Dominique 99
Dervishi Sokol 67
Desmedt Johan 19, 28, 61
Desmyter Jan 32
Dhalluin Adrien 14
Diakaki Christina 38
Dias Maria João 86
Dicaire Dan 12
Dikici Derya 61, 99
Dimitriu Sorin 40, 99
Dincer Ibrahim 30, 34
Djamel Alkama 40, 66
Djuric Natasa 50
Dobosi Ioan Silviu 55, 55, 79
Doğrul Ali 42
Doi Kota 63
Dolezilkova Hana 9
Dolmans Dick 84
Dombi Veronica Elvira 77
Dominique Marchio 39
Dong Bing 89
Dönmez Aydın Hacı 42
Doosam Song 22
Doppelbauer Eva Maria 44
Dorgan Chad B 72
Döring Bernd 24
Dornelles Kelen Almeida 91
Dovjak Mateja 11, 65
Doya Maxime 34
Dragos Hera 26, 60
Druette Lionel 88
Drughean Liviu Geo 72
Du Hu 10
Dubrow David 40
Duer Karsten 31, 46, 67
Duijm Frans 62
Dulc Matej 40
Dumitrescu Rodica 37, 43
Durisova Emilia 23
Duyvis Martina 74
Dyck Alf 76
Eayni Malekabodi Ali 34
Edge Jerry S. 10
Eggers Inga 32
Egido Manzano Moisés 86
Eğrican N. 70
Ekberg Lars 93
Ekberg Lars E. 62
Ekmekçi İsmail 70
El Mankibi Mohamed 28
Elena Palomo Del Barrio 34
Elsadi Hafia 84
Emmi Giuseppe 79
Enache Dumitru Stefan 49
Enai Masamichi 72, 72
Engel Peter Van Den 22
Entius Jordy 69
Eordoghne Miklos Maria 31
Eralp Cahit 26
Calculating heating and cooling loads in a room by developing a transient thermal simulation approach coupled with a zonal air model
Ali Kazemipour1, Aziz Azimi2, Siamak Kazemzadeh Hannani1 1Sharif University of Technology, Tehran, Iran 2Chamran University, Ahvaz, Iran Corresponding email: [email protected] SUMMARY Implementation of simple and effective models is essential to many applications such as building performance diagnosis and optimal control. Simple models are based on many ad-hoc assumptions and may not always reflect the physical behaviors. On the other hand, detailed physical models are time consuming and often not cost-effective. In this study, a heat balance method coupled with an air zonal model was utilized to make up a simple and fast but powerful method to simulate thermal behavior of buildings. Equations for transient heat transfer of walls are solved and radiation between walls, radiation through the window and storage of energy in the room are taken into consideration. For conservation equations for air, the very simple bulk (single node) model is replaced by a zonal model and thus air circulation and also temperature distribution in the room is predicted. The model showed compatible results with the experimental data and also the commercial software Carrier HAP. Keywords: Air Zonal Model, Building Thermal Modeling, Air Conditioning, Hourly Heating (Cooling) Load INTRODUCTION In all parts of the world, reasonable consumption of energy is important. Statistics indicate that the share of energy consumption in residential and commercial buildings is very high. As an example, almost 50 percent of the total energy produced is consumed in buildings in developed countries [1]. In Iran, according to the statistics obtained from the Iranian Fuel Conservation Company (IFCO), 39 percent of the energy produced, is consumed in buildings [2]. Therefore predicting thermal behavior of a building, mainly heating or cooling load behavior, is necessary for the optimization of its energy consumption. While simple calculations for building heating and cooling loads have a history of about a century, the first simulation models were produced in the 1960s [3]. Now, models for the thermal analysis of a building have a wide diversity, ranging from very simple models, such as manual HVAC calculations to full physical models such as computational fluid dynamics (CFD).
Among the methods to model the building heating and cooling loads, we can name Transfer Function Method (TFM) [3] that was introduced in 1967 by Mitalas and Stephenson [4] and Heat Balance Method (HTM) [3] that is a dynamic method for load calculation and was presented in 1990s by Pederson et al [5, 6]. In fact, the Transfer Function Method model lies in simplicity between very simple models which ignore the effects mass (steady state models) and complex and complete ones like Heat Balance Method. TFM is employed by some commercial software such as Carrier HAP [ 4, 7, 8]. TFM or simpler models are not useful for transient modeling. For instance, predicting the next-24-hour load in a building is essential for the optimal control of HVAC systems that use thermal or cool storage technology and this prediction cannot be performed by use of simple models. To completely model the thermal behavior, one also needs to know about the velocity and temperature field in the building as a tool to use with the HTM. The question that arises is whether we can solve the governing equations (Momentum, energy and mass conservation equations) completely for the inside air to find the velocity and temperature field? The answer is almost negative. Because the building thermal simulation, is generally performed for several days and in transient mode, it would take a long time to obtain a complete solution of conservation equations. Therefore, we may need to use simpler models instead. The simplest way is to use a single node for a whole room. The most physical and most exact method is CFD which is not always practical. In between, there exist other models that are not as complex as CFD but are somehow accurate. Nodal model and zonal model are two of them [9]. In the nodal model which is rather a simple one, the whole room is divided into a network of nodes that are connected to each other by one-dimensional air flow paths. However, in the zonal approach, a (Cartesian) network of control volumes control is used. This model is very similar to the CFD model. In Figure 1, a schematic of the solution networks for the 4 models described is shown. In this study, we have used the Heat Balance Method. The method is dynamic and transient and solves of the heat balance equation for walls and the room. A zonal model is used for calculating the temperature and velocity field in the room. As explained later, it solves all (but simplified versions) of conservations equations for the room air.
Figure 1 - Comparison between different models for calculating the temperature and velocity field in a room.
MODELING In the study, equations for transient heat transfer of walls are solved and radiation between walls, radiation through the window and storage of energy in the room are taken into consideration. As explained before, to solve the conservation equations for air, a zonal model and thus air circulation and also temperature distribution in the room is predicted. 2.1. Heat Conduction Heat transfer within the walls, ceiling and floor is transient heat conduction. According to the dimensions and geometries of the walls, heat conduction can be regarded as one-dimensional. Boundary condition of walls on both sides is a combination of heat convection and flux. Convection boundary condition is due to removal (or addition) of heat from (to) the boundary because of convective heat transfer with the atmosphere. Flux boundary condition is due to radiative heat transfer mechanism. Knowing all of the above, the conduction heat transfer equation can be easily solved. We used the Finite Volume approach to solve it. 2.2. Radiation Between Walls If the surfaces of all walls are opaque and gray and also the radiation is uniform in all directions, radiation exchange between them will be the solution of the equation (1) [10]:
1 1 1 1 1 2 1 1 1 1
2 2 1 2 2 2 2 2 2 2
1 2
1 ...
1 ...
... ... ... ... ... ...
... 1
n
n
n n n n n n n n n
F F F J E
F F F J E
F F F J E
, (1)
Where, E is emission (energy emitted from your body as a result of its temperature), J is radiosity (sum of the emission and reflected fraction of radiation received or irradiation), and Fijs are shape coefficients between walls i and j. After solving this system of equations and by denoting irradiation (the total received radiation from all objects around) by G, we can find the net energy output from the surface i as:
i i iq J G , (2)
3.2. Room Thermal Equilibrium Room air temperature is changed due to heat exchange with the walls and inside equipment via convection and also the produced or extracted heat. Absorbed radiation or emission is negligible. The governing equation is as follows if we use the bulk (single node) model:
, ,air
air p air i s i air fur fur air geni
dTm c h T T h T T Q
dt , (3)
Where Ts,i and Tfur are respectively the temperature of surface i (walls, windows, roof, …) and temperature of accessories, internal walls and other components in the room and Qgen, is the heat production term. The term containing equipments’ temperature, is due to heat transfer via
convection; this equipments get warm due to absorption of incoming radiation and give back their energy via heat convection to the air. An equipment’s temperature changes because of heat exchange with the air. The equipments may have temperature gradients inside, but because the lack of information and increasing in complexity of the model, the gradient is neglected and an average temperature is used for the whole equipments. Heat balance for the equipments is as follows:
, ,fur
fur p fur fur fur air Rad in
dTm c h T T q
dt , (4)
In which, QRad,in is the net radiation of heat into the equipments. 2.4. Zonal model The formulation in the previous section, was based on simple bulk model (single node) for room air. As mentioned earlier, the bulk model uses only a single node in the room. Thus no air flow exists, and temperature gradient is neglected. In this model, as any energy is input from any point of the room, the whole room temperature will change. The zonal model used, assumes that the flow mass flow is produced only by the effect of pressure difference. This assumption may be true for the low velocity flow inside a room. So we assume the mass flow from region j to region i that have a common vertical border (Fig. 2 a), to be as [11, 12]:
1
22ij j i ij d ij ijm m C A P , (5)
In which,Pij=Pj-Pi and, ij=sign(Pij) . The density used depends on the flow direction; is the density of the volume from which the fluid flows to another. I.e., if the flow is from region j to region i ( ij=1), then and vice versa. Similarly, the mass flow between two volumes having a common vertical border (Fig. 2 b) is:
1
212
2
1
2
ij j i ij d ij ij i i j j
ij ij i i j j
m m C A P gh gh
sign P gh gh
, (6)
Used coefficient CD is a discharge coefficient which must be determined before we can perform calculations. However, this coefficient can be variable, but the in our zonal model, we pick a fixed value. Research results indicate that for the case of flow due to free convection, a value of about 0.3-0.6 produces acceptable results [11, 12]. Mass and energy conservation equations for node i can be written as follows:
0ijj
m , (7)
,, 0 , 0 :
0ij ij
j iij p j ij p i n k i wall n i
j m j m j n wallsij
T Tm c T m c T k h A T T
x
, (8)
a)
b)
Figure 2 - Flow between two zones with different pressures; a) zones with a common vertical border (a) zones with a common horizontal border These relations are obtained using two assumptions (other the assumption of pressure-driven flow) for the zonal model. These assumptions are: • Thermal dissipation terms in the energy equation are neglected. • Due to very low speeds, air can be considered incompressible. 3. RESULTS 3.1. Validation of Zonal Model Results We first choose to validate the results of the zonal model. For this purpose, we compared our result with experimental results and also with the results of Boukhris et al [12]. The test case was a parallelepiped cell formed by two single volumes connected by a doorway and was called Minibat. The experimental were fulfilled by Boukhris et al. The shape and dimensions of the cell is presented in Fig. 3.
Figure 3. The shape and dimensions of the test cell In the case that was studied by Boukhris, the cell was equipped with a cold south face. Table 1 gives the values of average inside surface temperatures measured. Table 1. Values of average inside temperature (°C)
North South East West Ceiling Floor
17.93 11.7 17.20 17.32 17.1 16.71
A comparison of Boukhris’s results, experimental data and those from present work is given in Fig. 4 (a and b) for the air temperature on cold and warm sides of the partition. As seen, good agreement is achived. Deviation between calculated and measured temperatures was within 0.5 °C in the cold room, and less than 0.6 °C in the warm room.
a) b) Figure 4. Comparison of vertical distribution of air temperature on, a) the warm side and b) the cold side, of the Minibat cell. 3.2. Hourly Heating and Cooling Load Prediction For the 24-hour analysis, two sample rooms were selected in Tehran, Iran and the heating and cooling loads during the day were calculated and compared with Carrier HAP results. The results were for a quasi-transient situation. That is, the outdoor condition (for example outside temperature) has the same hourly profile for multiple days. So the hourly load profiles will be the same for all days. We did not simulate the conditions with a sudden change in outdoor conditions. For our study, two different days, one in July and the other in winter January were selected. Model input data, i.e. climate data, including temperature and solar radiation flux, was extracted from Carrier HAP software. The selected rooms, were quite simple and all the four walls and the ceiling were exposed to unconditioned (outside) space. In the first room, no windows existed and in the second one, a window was located on the south wall. The room area was 16 square meters. The plans of the rooms are shown in Fig. 5. The materials used for the ceiling, walls and windows are as shown in Table 2.
a) b)
Figure 5. Plans of the rooms, a) with window and b) without window.
Table 2. The materials used for the room.
Enclosure Layers Thickness (mm)
Specific Heat (J/kg K)
Density (kg/m3)
Conductivity (W/m K)
Absorptivity
North & South Walls
3 15 100 100
1090 840 920
801 609 2002
0.161 0.381 1.332
0.9
East & West Walls
3 15 150 100
1090 840 920
801 609 2002
0.161 0.381 1.332
0.9
Ceiling 3 25 10 100
920 1470 920
32 1121 2002
0.0208 0.1627 1.332
0.9
Windows 1 (Single glazing)
6 2000 2000 1 0.081 (Reflectance= 0.078)
Figures 6 and 7 show the results for hourly loads during a day for the two rooms. The results show that there is a very good agreement between our results and those of the Carrier HAP. As can be seen, maximum percentage of difference in heating loads is less than 2 and in cooling loads is about 10. Thus, so developed model for computing heat and cooling has passed validation test and is reliable.
a) b) Figure 6. Comparison of carrier and present work for hourly load for the room without window, a) in July and b) in January.
a) b) Figure 7. Comparison of carrier and present work for hourly load for the room with window, a) in July and b) in January.
4. DISCUSSION In this study, we studied the thermal modeling of a room; a model developed for numerical analysis of heating and cooling loads in a room. The thermal model developed included the complete and transient one-dimensional solution of heat conduction in the walls and windows, radiation heat exchange between walls, radiation through windows and a zonal model for room air. Zonal models was employed in order to find a relatively precise temperature field in the room on one hand and to reduce the complexities associated with the CFD model on the other hand. The presented new model provides good results, so that the hourly loads showed good agreement with the results of Carrier HAP software. It means that it can be used as a substitute. But the advantage over these quasi steady modeling is that the new model can predict the loads in a fully transient situation rather than a repeating 24-hour outdoor situations. As a future work, experimental data should be collected in order to validate the transient results obtained from the model. REFERENCES 1. Novoselac, A., Combined airflow and energy simulation program for building mechanical system design. 2005, The Pennsylvania State University.
2. Iranian Fuel Conservation Company (IFCO), http://www.ifco.ir/building/building_index.asp
3. Nikoofard, S., Calculating energy consumption of different heating equipments for the efficient design of energy consuming eqipments, M.Sc. Thesis, Sharif University of Technology, 2007.
4. Stephenson, D.G. and G.P. Mitalas, Cooling load calculations by thermal response factor method. ASHRAE Transactions, 1967. 73(1): p. 508-515.
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