Milorad Bojic - Profile on Academia.edu (original) (raw)
Papers by Milorad Bojic
The light pipes are innovative devices able to transport and distribute natural light without hea... more The light pipes are innovative devices able to transport and distribute natural light without heat transfer in dark rooms. There are a lot of natural lighting applications able to predict the behaviour of light in a room through a traditional opening. Only few of them are able to model complex systems such as daylight guidance systems. Added to this, they seem to provide disparate and inconsistent results with respect to the actual performance of light pipes. The purpose of this publication is to present the approach undertaken and the results obtained to highlight the problem. To do this, a survey of the different programs has been carried out internationally to model tubular devices. Then, an inter-software comparative analysis was implemented for some of the applications listed. In order to assess the accuracy of numerical results, the results of an experiment - 1:1 scale and in real weather conditions - were used as references to evaluate the chosen applications. We saw that the various selected programs tend to overestimate or underestimate the real phenomenon. The use of an experimental database permitted to put forward the most efficient applications. These results support the future goal to develop a new model. Future prospects of our study that can emerge are mainly based on the introduction of a new model for predicting the performance of light pipes and its integration in two software products developed within laboratory: CODYRUN (a multi-zone software integrating thermal building simulation, airflow transfers, lighting and pollutants) and HEMERA (a daylighting analysis software).
Decreasing Energy Use and Influence to Enviroment by Radiant Panel Heating Using Different Energy Sources
Applied Energy, 2015
In Serbia, radiant heating is increasingly used. Also, in Serbia, the largest portion of produced... more In Serbia, radiant heating is increasingly used. Also, in Serbia, the largest portion of produced electricity is from the fossil fuels which results in a high value of primary energy consumption coefficient (R). This situation raises the question of the justification of the use of ground sources heat pump (GHSP) over natural gas boiler and GSHP with PV array. Also, the impact of the embodied energy and embodied carbon was included in this paper. The operation of this house is simulated by software EnergyPlus. The results indicated that the newly-developed floor-ceiling radiant heating system has the best performances and classical ceiling heating has the worst performances. However in future with decrease of R, it is shown that the panel heating powered by GSHP may have lower total energy consumption than that of such a system powered by natural gas. For the wall panel heating, this would happen for the highest value of R, while in the case of the ceiling heating, it would appear for the lowest value of R.
Linear programming optimization of heat distribution in a district-heating system by valve adjustments and substation retrofit
Building and Environment, 2000
The unbalanced distribution of heat in a district-heating system may be caused by the increase of... more The unbalanced distribution of heat in a district-heating system may be caused by the increase of hydraulic resistance of pipe network, decrease of heat transmittance of radiators inside buildings, and increase of heat transmittance of building envelope. This situation yields the overheating of some buildings and underheating of other buildings. A district-heating system is analyzed that consists of heat plant, primary pipe network, substation, secondary pipe network, and three buildings. A steady-state, bottom-up approach and the ...
Thermoelectric cooling of a train carriage by using a coldness-recovery device
Energy, 1997
We have used a thermoelectric cooler and a coldness-recovery device (CRD) for summer air conditio... more We have used a thermoelectric cooler and a coldness-recovery device (CRD) for summer air conditioning of a train carriage. The coldness-recovery device is a countercurrent heat exchanger. This air-conditioning system is described in terms of a heat-exchanger network for which we have developed computer software (GOLAM2-R). We have simulated six different control scenarios for the energy system. Use of the coldness-recovery device produces a higher COP than an increase of the Peltier coefficient for the thermoelectric ...
Energy from a two-pipe, earth-to-air heat exchanger
Energy, 1999
Solar energy accumulated in the soil may be utilized with an air-to-earth heat exchanger (ATEHE) ... more Solar energy accumulated in the soil may be utilized with an air-to-earth heat exchanger (ATEHE) which has two pipes buried in the soil, one made of PVC and one of steel. During the winter, air is heated; during the summer, it is cooled and then used in an air-conditioning device. To obtain the mathematical model of the ATEHE, we divided the soil and pipes into elementary volumes, used steady-state energy equations, and applied a time-marching method. We determined how the season, soil thermal conductivity and pipe spacing ...
Energy and Buildings, 2000
A district-heating system transports heat from the heat plant by using primary pipe network, via ... more A district-heating system transports heat from the heat plant by using primary pipe network, via substation, to secondary pipe network where heat is finally distributed to buildings. When this system is designed its operational characteristics were selected to provide thermal Ž . comfort TC in all buildings served by this district heating system. After several years of operation, the system characteristics may change and TC in buildings deteriorates; some buildings are overheated and other buildings are underheated. The study investigates an optimum strategy to mitigate the problem caused by changes of three of system characteristics: hydraulic resistance of secondary pipe network, heat transmittance of radiators inside buildings, and heat transmittance of building envelope. A strategy of problem mitigation consists of the adjustment of hydraulic resistance of existing valves and retrofitting the local heating system with new substation heat exchanger and additional pumps. We used a steady state, bottom-up approach and mixed 0-1 sequential linear programming to find optimal mitigation strategy, i.e. optimum combination of valves' hydraulic resistances, new pumps placement and new size of substation heat exchanger. The results indicate that the calculated optimal strategy does not effectively improve TC in buildings only in cases when TC is deteriorated by higher than nominal values of heat transmittance of some building envelopes. q 2000 Elsevier Science S.A. All rights reserved.
Energy and Buildings, 2001
Recessed spaces outside high-rise residential buildings of public-type in Hong Kong often contain... more Recessed spaces outside high-rise residential buildings of public-type in Hong Kong often contain a large number of condenser units of window-type air-conditioners that during summer reject heat into this space at the same time. For four condenser units per story, a computational¯uid dynamics (CFD) code is used to predict temperature and¯ow ®elds inside the recessed spaces that differ in heights and condenser-unit locations. The results show that a powerful rising hot air stream and one vortex pair are formed in the space near to its corner wall. In addition, the results show that condenser units will suffer more when they are placed inside the taller recessed space, and at locations higher at this space and nearer to its corner wall. Then, these units would draw less air at an elevated temperature, and therefore become less energy ef®cient and de-rated in output capacity and sometime have interrupted operation. However, the condenser units at lower levels may bene®t because they will draw more air at nearly environmental temperature. #
Energy Conversion and Management, 2002
Thermal insulation is seldom applied to the fabric of high rise residential buildings in Hong Kon... more Thermal insulation is seldom applied to the fabric of high rise residential buildings in Hong Kong. Where it is used, it is placed in the fabric component at the side that faces the outdoors or non-air conditioned spaces, such as kitchens, bathrooms and entrance lobbies. The paper reports on the results of an investigation into the eects of including a thermal insulation layer in the fabric components that separate cooled spaces from the outdoors and from non-air conditioned spaces. In the investigation, the eects of placing the insulation layer at the indoor side, in the middle and at the outdoor side, or the side of the adjacent nonair conditioned space, of the fabric components were evaluated and compared. For the doors, the insulation layer was always put between the two face panels. The detailed building heat transfer simulation program HTB2 was employed to calculate the yearly cooling loads and the maximum cooling demand in the year of two typical¯ats in a high rise residential building. The simulation predictions show that the highest reduction in the yearly cooling load, by 9.1%, and in the maximum cooling demand, by 10.5%, would be achieved when a 50 mm thick thermal insulation layer was placed at the indoor side of the walls that enclose the cooled spaces. However, increasing the thickness of the insulation layer beyond 50 mm and of the concrete layer to above 100 mm would only lead to insigni®cant further reductions in the yearly cooling load and the yearly maximum cooling demand. Ó
Energy and Buildings, 2002
At the present time in Hong Kong in its hot and humid climate, a single pane, clear glazing is mo... more At the present time in Hong Kong in its hot and humid climate, a single pane, clear glazing is most often used in windows of tall residential buildings. During this study, we employed HTB2, detailed building heat transfer simulation software, to evaluate a decrease in the yearly cooling load (Q) and in the peak cooling-load (D) in two residential¯ats due to different glazing single pane types and different at orientations. The investigated glazing types were clear glazing, tinted glazing, re¯ective glazing, and tinted and re¯ective glazing. #
Linear programming applied to an industrial building with several available hot refuse flows
Energy, 1995
We use a recovery heat exchanger (RHE) in an industrial building to heat incoming air for space h... more We use a recovery heat exchanger (RHE) in an industrial building to heat incoming air for space heating by using the heat contents of some of the refuse hot-air flows (RAF). Several RAFs are often available with different flow rates and temperatures. A proper scenario for use of their heat contents is essential for efficient management of the energy system. Using a steady-state, bottom-up approach, we have obtained a set of equations that we have linearized. Linear programming (LP) is then used and LINE software has been developed. ...
Energy Conversion and Management, 2002
An evaporative three finger thermosyphon (ETT), made entirely of glass, is comprised of three fin... more An evaporative three finger thermosyphon (ETT), made entirely of glass, is comprised of three fingers, where one was an evaporator and two were condensers. As evaporating liquid and saturated vapor, water was used inside the ETT, and air was present inside the ETT's condenser fingers, at their tops. This air enables a variation of the effective heat transfer area inside the condensers and, thus, a control of the heat transfer from the evaporator to the two condensers. The cold water used to cool condenser 1 had a cross flow area smaller than that used to cool condenser 2. Experimental investigations revealed that the ETT behavior was controlled by the evaporator heater and by the cooling water in condenser 2. These control features change with elapsed operation time. The ETT behavior was not controlled by the cooling water in condenser 1. Ó
Numerical simulation, technical and economic evaluation of air-to-earth heat exchanger coupled to a building
Energy, 1997
An air-to-earth heat exchanger (ATEHE) consists of pipes buried in soil. We have evaluated the te... more An air-to-earth heat exchanger (ATEHE) consists of pipes buried in soil. We have evaluated the technical and economic performance of an ATEHE coupled to the system for heating or cooling of a building that uses 100% fresh air as heating or cooling medium during winter and summer. The soil is divided into elementary layers. The problem solved, is non stationary; however, steady state-energy equations are used for soil layers in each time step. It is found that the use of the ATEHE covers a portion of the daily building needs for space ...
Energy and Buildings, 2002
During summer, a large number of air-conditioners at the same time could be rejecting condenser h... more During summer, a large number of air-conditioners at the same time could be rejecting condenser heat into a recessed space formed by the external walls outside many high-rise residential buildings in Hong Kong. Prediction of the temperature and¯ow ®eld of a powerful rising hot air stream formed in a 30-story high recessed space is performed by using FLUENT 5.0, a computational¯uid dynamics (CFD) code. For a 30-story high recessed space of``I'' type with four window-type air-conditioner units per story, this paper describes the ®ndings for two depths of the recessed space. For the buoyant air stream, the results show that the mass-¯ow rate and temperature inside the recessed space are not signi®cantly in¯uenced by the recessed space depth. For air streams used by the condenser units, deeper recessed space yields an increase in the enthalpy in the air stream used by the outer units, and a decrease in the enthalpy in the air stream used by the inner units, which draw the hottest air from the recessed space. #
Influence of envelope and partition characteristics on the space cooling of high-rise residential buildings in Hong Kong
Building and Environment, 2002
Nowadays, many apartments in residential buildings in Hong Kong are equipped with air-conditioner... more Nowadays, many apartments in residential buildings in Hong Kong are equipped with air-conditioners to provide comfort cooling for the living, dining and bedrooms. Air-conditioners serving the living and dining rooms would be operated mostly in the evenings and sometimes during daytime as well, but those serving the bedrooms could remain operating overnight. Other rooms, such as bathrooms and kitchens, will not normally be air-conditioned. The paper describes a study into the influence of the building envelope ...
Abstract: Due to the current environmental situation, energy saving has become the leading drive ... more Abstract: Due to the current environmental situation, energy saving has become the leading drive in modern research. Although the residential houses in tropical climate do not use air conditioning to maintain thermal comfort in order to avoid use of electricity. As the thermal comfort is maintained by adequate envelope composition and natural ventilation, this paper shows that it is possible to determine the thickness of envelope layers for which the best thermal comfort is obtained.
Energy from a two-pipe, earth-to-air heat exchanger
Solar energy accumulated in the soil may be utilized with an air-to-earth heat exchanger (ATEHE) ... more Solar energy accumulated in the soil may be utilized with an air-to-earth heat exchanger (ATEHE) which has two pipes buried in the soil, one made of PVC and one of steel. During the winter, air is heated; during the summer, it is cooled and then used in an air-conditioning device. To obtain the mathematical model of the ATEHE, we divided the soil and pipes into elementary volumes, used steady-state energy equations, and applied a time-marching method.
2011 Public Opinion Survey: Awareness on Energy Saving Needs in Serbia
SUMMARY Since the global environmental crisis, energy concerns increase in priority, and it is im... more SUMMARY Since the global environmental crisis, energy concerns increase in priority, and it is important to understand house residents' position on energy savings in different countries. This paper presents results of the 2011 public opinion survey in Serbia in city of Kragujevac. The survey examines the awareness of the Serbian public on energy savings in low-rise housing. The investigation found out that about 43% of respondents do care about energy saving when they build the house and 94% when they operate the house.
Performances of Low Temperature Radiant Heating Systems
SUMMARY Low temperature heating panel systems offer distinctive advantages in terms of thermal co... more SUMMARY Low temperature heating panel systems offer distinctive advantages in terms of thermal comfort and energy consumption, allowing work with low exergy sources. The purpose of this paper is to compare floor, wall, ceiling, and floor-ceiling panel heating systems in terms of energy, exergy and CO2 emissions.
At the Faculty of Mechanical Engineering of Kragujevac, a heat pump (water–water) was installed a... more At the Faculty of Mechanical Engineering of Kragujevac, a heat pump (water–water) was installed as a design made by the senior undergraduates within the academic course Heating and Air-conditioning. This project was financed by ASHRAE. Using electrical power on its compressor, the heat pump transfers heat from the heat source (lower temperature) to the cold source (heat sink)(higher temperature), which comprises central heating radiators, floor heating system and technical water heating system.
The light pipes are innovative devices able to transport and distribute natural light without hea... more The light pipes are innovative devices able to transport and distribute natural light without heat transfer in dark rooms. There are a lot of natural lighting applications able to predict the behaviour of light in a room through a traditional opening. Only few of them are able to model complex systems such as daylight guidance systems. Added to this, they seem to provide disparate and inconsistent results with respect to the actual performance of light pipes. The purpose of this publication is to present the approach undertaken and the results obtained to highlight the problem. To do this, a survey of the different programs has been carried out internationally to model tubular devices. Then, an inter-software comparative analysis was implemented for some of the applications listed. In order to assess the accuracy of numerical results, the results of an experiment - 1:1 scale and in real weather conditions - were used as references to evaluate the chosen applications. We saw that the various selected programs tend to overestimate or underestimate the real phenomenon. The use of an experimental database permitted to put forward the most efficient applications. These results support the future goal to develop a new model. Future prospects of our study that can emerge are mainly based on the introduction of a new model for predicting the performance of light pipes and its integration in two software products developed within laboratory: CODYRUN (a multi-zone software integrating thermal building simulation, airflow transfers, lighting and pollutants) and HEMERA (a daylighting analysis software).
Decreasing Energy Use and Influence to Enviroment by Radiant Panel Heating Using Different Energy Sources
Applied Energy, 2015
In Serbia, radiant heating is increasingly used. Also, in Serbia, the largest portion of produced... more In Serbia, radiant heating is increasingly used. Also, in Serbia, the largest portion of produced electricity is from the fossil fuels which results in a high value of primary energy consumption coefficient (R). This situation raises the question of the justification of the use of ground sources heat pump (GHSP) over natural gas boiler and GSHP with PV array. Also, the impact of the embodied energy and embodied carbon was included in this paper. The operation of this house is simulated by software EnergyPlus. The results indicated that the newly-developed floor-ceiling radiant heating system has the best performances and classical ceiling heating has the worst performances. However in future with decrease of R, it is shown that the panel heating powered by GSHP may have lower total energy consumption than that of such a system powered by natural gas. For the wall panel heating, this would happen for the highest value of R, while in the case of the ceiling heating, it would appear for the lowest value of R.
Linear programming optimization of heat distribution in a district-heating system by valve adjustments and substation retrofit
Building and Environment, 2000
The unbalanced distribution of heat in a district-heating system may be caused by the increase of... more The unbalanced distribution of heat in a district-heating system may be caused by the increase of hydraulic resistance of pipe network, decrease of heat transmittance of radiators inside buildings, and increase of heat transmittance of building envelope. This situation yields the overheating of some buildings and underheating of other buildings. A district-heating system is analyzed that consists of heat plant, primary pipe network, substation, secondary pipe network, and three buildings. A steady-state, bottom-up approach and the ...
Thermoelectric cooling of a train carriage by using a coldness-recovery device
Energy, 1997
We have used a thermoelectric cooler and a coldness-recovery device (CRD) for summer air conditio... more We have used a thermoelectric cooler and a coldness-recovery device (CRD) for summer air conditioning of a train carriage. The coldness-recovery device is a countercurrent heat exchanger. This air-conditioning system is described in terms of a heat-exchanger network for which we have developed computer software (GOLAM2-R). We have simulated six different control scenarios for the energy system. Use of the coldness-recovery device produces a higher COP than an increase of the Peltier coefficient for the thermoelectric ...
Energy from a two-pipe, earth-to-air heat exchanger
Energy, 1999
Solar energy accumulated in the soil may be utilized with an air-to-earth heat exchanger (ATEHE) ... more Solar energy accumulated in the soil may be utilized with an air-to-earth heat exchanger (ATEHE) which has two pipes buried in the soil, one made of PVC and one of steel. During the winter, air is heated; during the summer, it is cooled and then used in an air-conditioning device. To obtain the mathematical model of the ATEHE, we divided the soil and pipes into elementary volumes, used steady-state energy equations, and applied a time-marching method. We determined how the season, soil thermal conductivity and pipe spacing ...
Energy and Buildings, 2000
A district-heating system transports heat from the heat plant by using primary pipe network, via ... more A district-heating system transports heat from the heat plant by using primary pipe network, via substation, to secondary pipe network where heat is finally distributed to buildings. When this system is designed its operational characteristics were selected to provide thermal Ž . comfort TC in all buildings served by this district heating system. After several years of operation, the system characteristics may change and TC in buildings deteriorates; some buildings are overheated and other buildings are underheated. The study investigates an optimum strategy to mitigate the problem caused by changes of three of system characteristics: hydraulic resistance of secondary pipe network, heat transmittance of radiators inside buildings, and heat transmittance of building envelope. A strategy of problem mitigation consists of the adjustment of hydraulic resistance of existing valves and retrofitting the local heating system with new substation heat exchanger and additional pumps. We used a steady state, bottom-up approach and mixed 0-1 sequential linear programming to find optimal mitigation strategy, i.e. optimum combination of valves' hydraulic resistances, new pumps placement and new size of substation heat exchanger. The results indicate that the calculated optimal strategy does not effectively improve TC in buildings only in cases when TC is deteriorated by higher than nominal values of heat transmittance of some building envelopes. q 2000 Elsevier Science S.A. All rights reserved.
Energy and Buildings, 2001
Recessed spaces outside high-rise residential buildings of public-type in Hong Kong often contain... more Recessed spaces outside high-rise residential buildings of public-type in Hong Kong often contain a large number of condenser units of window-type air-conditioners that during summer reject heat into this space at the same time. For four condenser units per story, a computational¯uid dynamics (CFD) code is used to predict temperature and¯ow ®elds inside the recessed spaces that differ in heights and condenser-unit locations. The results show that a powerful rising hot air stream and one vortex pair are formed in the space near to its corner wall. In addition, the results show that condenser units will suffer more when they are placed inside the taller recessed space, and at locations higher at this space and nearer to its corner wall. Then, these units would draw less air at an elevated temperature, and therefore become less energy ef®cient and de-rated in output capacity and sometime have interrupted operation. However, the condenser units at lower levels may bene®t because they will draw more air at nearly environmental temperature. #
Energy Conversion and Management, 2002
Thermal insulation is seldom applied to the fabric of high rise residential buildings in Hong Kon... more Thermal insulation is seldom applied to the fabric of high rise residential buildings in Hong Kong. Where it is used, it is placed in the fabric component at the side that faces the outdoors or non-air conditioned spaces, such as kitchens, bathrooms and entrance lobbies. The paper reports on the results of an investigation into the eects of including a thermal insulation layer in the fabric components that separate cooled spaces from the outdoors and from non-air conditioned spaces. In the investigation, the eects of placing the insulation layer at the indoor side, in the middle and at the outdoor side, or the side of the adjacent nonair conditioned space, of the fabric components were evaluated and compared. For the doors, the insulation layer was always put between the two face panels. The detailed building heat transfer simulation program HTB2 was employed to calculate the yearly cooling loads and the maximum cooling demand in the year of two typical¯ats in a high rise residential building. The simulation predictions show that the highest reduction in the yearly cooling load, by 9.1%, and in the maximum cooling demand, by 10.5%, would be achieved when a 50 mm thick thermal insulation layer was placed at the indoor side of the walls that enclose the cooled spaces. However, increasing the thickness of the insulation layer beyond 50 mm and of the concrete layer to above 100 mm would only lead to insigni®cant further reductions in the yearly cooling load and the yearly maximum cooling demand. Ó
Energy and Buildings, 2002
At the present time in Hong Kong in its hot and humid climate, a single pane, clear glazing is mo... more At the present time in Hong Kong in its hot and humid climate, a single pane, clear glazing is most often used in windows of tall residential buildings. During this study, we employed HTB2, detailed building heat transfer simulation software, to evaluate a decrease in the yearly cooling load (Q) and in the peak cooling-load (D) in two residential¯ats due to different glazing single pane types and different at orientations. The investigated glazing types were clear glazing, tinted glazing, re¯ective glazing, and tinted and re¯ective glazing. #
Linear programming applied to an industrial building with several available hot refuse flows
Energy, 1995
We use a recovery heat exchanger (RHE) in an industrial building to heat incoming air for space h... more We use a recovery heat exchanger (RHE) in an industrial building to heat incoming air for space heating by using the heat contents of some of the refuse hot-air flows (RAF). Several RAFs are often available with different flow rates and temperatures. A proper scenario for use of their heat contents is essential for efficient management of the energy system. Using a steady-state, bottom-up approach, we have obtained a set of equations that we have linearized. Linear programming (LP) is then used and LINE software has been developed. ...
Energy Conversion and Management, 2002
An evaporative three finger thermosyphon (ETT), made entirely of glass, is comprised of three fin... more An evaporative three finger thermosyphon (ETT), made entirely of glass, is comprised of three fingers, where one was an evaporator and two were condensers. As evaporating liquid and saturated vapor, water was used inside the ETT, and air was present inside the ETT's condenser fingers, at their tops. This air enables a variation of the effective heat transfer area inside the condensers and, thus, a control of the heat transfer from the evaporator to the two condensers. The cold water used to cool condenser 1 had a cross flow area smaller than that used to cool condenser 2. Experimental investigations revealed that the ETT behavior was controlled by the evaporator heater and by the cooling water in condenser 2. These control features change with elapsed operation time. The ETT behavior was not controlled by the cooling water in condenser 1. Ó
Numerical simulation, technical and economic evaluation of air-to-earth heat exchanger coupled to a building
Energy, 1997
An air-to-earth heat exchanger (ATEHE) consists of pipes buried in soil. We have evaluated the te... more An air-to-earth heat exchanger (ATEHE) consists of pipes buried in soil. We have evaluated the technical and economic performance of an ATEHE coupled to the system for heating or cooling of a building that uses 100% fresh air as heating or cooling medium during winter and summer. The soil is divided into elementary layers. The problem solved, is non stationary; however, steady state-energy equations are used for soil layers in each time step. It is found that the use of the ATEHE covers a portion of the daily building needs for space ...
Energy and Buildings, 2002
During summer, a large number of air-conditioners at the same time could be rejecting condenser h... more During summer, a large number of air-conditioners at the same time could be rejecting condenser heat into a recessed space formed by the external walls outside many high-rise residential buildings in Hong Kong. Prediction of the temperature and¯ow ®eld of a powerful rising hot air stream formed in a 30-story high recessed space is performed by using FLUENT 5.0, a computational¯uid dynamics (CFD) code. For a 30-story high recessed space of``I'' type with four window-type air-conditioner units per story, this paper describes the ®ndings for two depths of the recessed space. For the buoyant air stream, the results show that the mass-¯ow rate and temperature inside the recessed space are not signi®cantly in¯uenced by the recessed space depth. For air streams used by the condenser units, deeper recessed space yields an increase in the enthalpy in the air stream used by the outer units, and a decrease in the enthalpy in the air stream used by the inner units, which draw the hottest air from the recessed space. #
Influence of envelope and partition characteristics on the space cooling of high-rise residential buildings in Hong Kong
Building and Environment, 2002
Nowadays, many apartments in residential buildings in Hong Kong are equipped with air-conditioner... more Nowadays, many apartments in residential buildings in Hong Kong are equipped with air-conditioners to provide comfort cooling for the living, dining and bedrooms. Air-conditioners serving the living and dining rooms would be operated mostly in the evenings and sometimes during daytime as well, but those serving the bedrooms could remain operating overnight. Other rooms, such as bathrooms and kitchens, will not normally be air-conditioned. The paper describes a study into the influence of the building envelope ...
Abstract: Due to the current environmental situation, energy saving has become the leading drive ... more Abstract: Due to the current environmental situation, energy saving has become the leading drive in modern research. Although the residential houses in tropical climate do not use air conditioning to maintain thermal comfort in order to avoid use of electricity. As the thermal comfort is maintained by adequate envelope composition and natural ventilation, this paper shows that it is possible to determine the thickness of envelope layers for which the best thermal comfort is obtained.
Energy from a two-pipe, earth-to-air heat exchanger
Solar energy accumulated in the soil may be utilized with an air-to-earth heat exchanger (ATEHE) ... more Solar energy accumulated in the soil may be utilized with an air-to-earth heat exchanger (ATEHE) which has two pipes buried in the soil, one made of PVC and one of steel. During the winter, air is heated; during the summer, it is cooled and then used in an air-conditioning device. To obtain the mathematical model of the ATEHE, we divided the soil and pipes into elementary volumes, used steady-state energy equations, and applied a time-marching method.
2011 Public Opinion Survey: Awareness on Energy Saving Needs in Serbia
SUMMARY Since the global environmental crisis, energy concerns increase in priority, and it is im... more SUMMARY Since the global environmental crisis, energy concerns increase in priority, and it is important to understand house residents' position on energy savings in different countries. This paper presents results of the 2011 public opinion survey in Serbia in city of Kragujevac. The survey examines the awareness of the Serbian public on energy savings in low-rise housing. The investigation found out that about 43% of respondents do care about energy saving when they build the house and 94% when they operate the house.
Performances of Low Temperature Radiant Heating Systems
SUMMARY Low temperature heating panel systems offer distinctive advantages in terms of thermal co... more SUMMARY Low temperature heating panel systems offer distinctive advantages in terms of thermal comfort and energy consumption, allowing work with low exergy sources. The purpose of this paper is to compare floor, wall, ceiling, and floor-ceiling panel heating systems in terms of energy, exergy and CO2 emissions.
At the Faculty of Mechanical Engineering of Kragujevac, a heat pump (water–water) was installed a... more At the Faculty of Mechanical Engineering of Kragujevac, a heat pump (water–water) was installed as a design made by the senior undergraduates within the academic course Heating and Air-conditioning. This project was financed by ASHRAE. Using electrical power on its compressor, the heat pump transfers heat from the heat source (lower temperature) to the cold source (heat sink)(higher temperature), which comprises central heating radiators, floor heating system and technical water heating system.
Poster for ISES Congress (Nov. 2013) at Cancun (Mexico)