The Experts below are selected from a list of 23619 Experts worldwide ranked by ideXlab platform
Shiming Deng - One of the best experts on this subject based on the ideXlab platform.
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inherent operational characteristics aided fuzzy logic controller for a variable speed direct expansion Air conditioning system for simultaneous Indoor Air Temperature and humidity control
Energy and Buildings, 2018Co-Authors: Huaxia Yan, Yudong Xia, Shiming DengAbstract:Abstract In small to medium sized buildings, direct expansion (DX) A/C systems are extensively used. Multi-variable controllers (MVCs) have been developed for variable speed (VS) DX A/C systems to control Indoor Air Temperature and humidity simultaneously. Based on the previous extensive research work on the inherent operational characteristics of DX A/C systems, an alternative simpler approach was applied, by developing a fuzzy logic controller (FLC) for simultaneous Indoor Air Temperature and humidity control, using a VS DX A/C system. In this paper, the developments of the FLC are presented. Firstly, a detailed description of the algorithm for the FLC is given. This is followed by detailing an experimental VS DX A/C system where the FLC was tested. Finally, the results of controllability tests for the FLC are reported. Controllability tests results demonstrated that the FLC developed can achieve the simultaneous control over Indoor Air Temperature and humidity, with a reasonable control accuracy and sensitivity.
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simulation study on a three evaporator Air conditioning system for simultaneous Indoor Air Temperature and humidity control
Applied Energy, 2017Co-Authors: Huaxia Yan, Yudong Xia, Shiming DengAbstract:Abstract A multi-evaporator Air conditioning (MEAC) system, which may also be called a multi-split Air conditioning system or variable refrigerant flow system in the open literature, may be regarded as one of the energy conscious Air conditioning applications. However, most MEAC systems currently focus on Air Temperature control only, so that the potential of using MEAC system in achieving energy saving has not yet been fully utilized. In this paper, based on the previous extensive related research on modeling and controlling both single evaporator Air conditioning systems and MEAC systems, a capacity controller for a three-evaporator Air conditioning (TEAC) system was developed. Results of simulative controllability tests for the capacity controller demonstrated that, Indoor Air Temperature could be directly controlled using the capacity controller, but Indoor relative humidity can be improved and maintained at acceptable levels. Based on the operating characteristics of the TEAC system, the capacity controller was further improved and thus an improved controller was developed. Two tests to verify the performances of the improved controller were conducted. The test results showed that simultaneous Indoor Air Temperature and humidity control of a TEAC system could be achieved using the improved controller.
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A novel hybrid steady-state model based controller for simultaneous Indoor Air Temperature and humidity control
Energy and Buildings, 2014Co-Authors: Shiming Deng, Xiaohong Han, Zhang XuejunAbstract:Abstract Due to the strong coupling between two control loops, it is always a challenge to develop appropriate control algorithm for simultaneously controlling Indoor Air Temperature and humidity using a direct expansion (DX) Air conditioning (A/C) system, making it an engineering application where no expert experience is available. Although the control performance of a steady state model based controller (SSMBC) was normally regarded to be not comparable to that of a dynamic model based controller, the successful development of a SSMBC may provide new insights of the control mechanism. In this paper, a SSMBC was developed based on a previous developed steady state model of a DX A/C system. Its control performance was theoretically analyzed and experimentally tested. It was proven that by utilizing a specific activating method, the SSMBC could achieve much better control performance than that of a traditional On-Off control method. However, the SSMBC could be further improved. Based on the theoretical analysis of the interaction between the changes of system operating states and those of Indoor Air thermal states, a hybrid SSMBC, which consisted of a SSMBC and a stabilizing controller, was further developed. The accuracy and sensitivity of the novel hybrid SSMBC are experimentally validated.
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multivariable control of Indoor Air Temperature and humidity in a direct expansion dx Air conditioning a c system
Building and Environment, 2009Co-Authors: Shiming DengAbstract:Abstract Controlling Indoor humidity at an appropriate level is very important since this affects occupants' thermal comfort and Indoor Air quality (IAQ). The paper presents an investigation on developing a multi-input multi-output (MIMO) control strategy for simultaneously controlling the Indoor Air Temperature and humidity by varying the speeds of both compressor and supply fan in an experimental DX A/C system. The MIMO-based controller was designed based on the linearized dynamic model of the experimental DX A/C system. The Linear Quadratic Gaussian (LQG) technique was used in designing the MIMO-based controller. The controllability tests with respect to both the disturbance rejection capability and the command following capability were carried out to assess the control performance of MIMO controller. The results of disturbance rejection capability test showed that the MIMO control strategy can effectively maintain the Indoor Air Temperature and humidity to their respective settings after an unmeasured heat load disturbance was imposed by simultaneously varying speeds of both the compressor and the supply fan of the DX A/C system. Furthermore, in the command following capability test for Indoor Air Temperature, the test results showed that the Indoor Air Temperature can be controlled to its new setting while Indoor humidity remained unchanged. Similar test results were also observed in the command following capability test for Indoor humidity. Therefore, the MIMO controller developed can effectively control Indoor Air Temperature and humidity simultaneously by varying compressor speed and supply fan speed of the DX A/C system. Compared to the previous related studies using conventional on–off control method or single-input single-output (SISO) control strategy, which can only effectively control either Air Temperature or relative humidity, the MIMO controller can simultaneously control the Indoor Air Temperature and humidity with adequate control sensitivity and accuracy. The application of MIMO control strategy developed can be extended to other HVAC systems in the future to improve their operating performance and energy efficiency.
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A New Control Approach for a Direct Expansion (DX) Air Conditioning (A/C)System with Variable Speed Compressor and Variable Speed Supply Fan
2008Co-Authors: Shiming DengAbstract:This paper presents a dynamic mathematical model for a DX A/C system which was suitable for designing multivariable control. A multi-input multi-output (MIMO) controller is designed based on the model to simultaneously control Indoor Air Temperature and humidity by varying the speeds of both compressor and supply fan. The experiment results show that MIMO control method is capable of simultaneously controlling Indoor Air Temperature and humidity, thus improving the thermal comfort. It is also expected that such a MIMO feedback control will have wide applications in HVAC&R systems to achieve high performance.
Rajiv Gupta - One of the best experts on this subject based on the ideXlab platform.
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COMPARATIVE THERMAL PERFORMANCE OF STATIC SUNSHADE AND BRICK CAVITY WALL FOR ENERGY EFFICIENT BUILDING ENVELOPE IN COMPOSITE CLIMATE
Thermal Science, 2014Co-Authors: Meghana Charde, Sourabh Bhati, Ayushman Kheterpal, Rajiv GuptaAbstract:Energy efficient building technologies can reduce energy consumption in buildings. In present paper effect of designed static sunshade, brick cavity wall with brick projections and their combined effect on Indoor Air Temperature has been analyzed by constructing three test rooms each of habitable dimensions (3.0 m × 4.0 m × 3.0 m) and studying hourly Temperatures on typical days for one month in summer and winter each. The three rooms have also been simulated using a software and the results have been compared with the experimental results. Designed static sunshade increased Indoor Air Temperature in winter while proposed brick cavity wall with brick projections lowered it in summer. Combined effect of building elements lowered Indoor Air Temperature in summer and increased it in winter as compared to outdoor Air Temperature. It is thus useful for energy conservation in buildings in composite climate.
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Effect of energy efficient building elements on summer cooling of buildings
Energy and Buildings, 2013Co-Authors: Meghana Charde, Rajiv GuptaAbstract:Abstract Growing energy demands with an increasing population have reiterated the importance of energy conservation. Buildings share a large portion of energy use worldwide. Energy efficient building technologies help to maximize solar heat gain in winter, minimize it in summer and optimize energy requirements in buildings. In present paper, effect of ventilated brick cavity wall with brick projections (independently and combined with designed static sunshade and hollow roof) on Indoor Air Temperature has been analyzed experimentally by constructing four rooms of habitable dimensions (3.0 m × 4.0 m × 3.0 m high) and studying average hourly Temperatures in summer. The combined effect of ventilated brick cavity wall with brick projections, designed static sunshade and hollow roof helped to lower Indoor Air Temperature for hotter part of the day in the study period. It also lowered maximum and minimum Indoor Air Temperature and swing in Indoor Air Temperature although there was a large variation in outdoor Air Temperature. Combined effect of the energy efficient building elements is thus useful for summer cooling and energy conservation in buildings.
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Annual Thermal Performance of a Hollow Roof in Combination with a Cavity Wall and Static Sunshade: Experimental Study of Energy-Efficient Rooms
Journal of Energy Engineering, 2013Co-Authors: Meghana Charde, Rajiv GuptaAbstract:AbstractEnergy consumption by the building sector constitutes a large portion of global energy use. Energy-efficient building technologies help to reduce heat gain in hot summer months, heat loss in cold winter months, and modify energy requirements in buildings. In the writers’ paper, the effect of a proposed hollow roof (independent of and combined with a designed brick-cavity wall with brick projections and static sunshade) on Indoor Air Temperature has been analyzed experimentally by constructing four rooms of habitable dimensions (3.0×4.0×3.0-m high) and studying average hourly Temperatures for 1 year. Each room has a different combination of type of roof, wall, and static sunshade; hence, the difference in Indoor Air Temperature of the rooms will primarily be attributable to differences in heat transferred through these building elements. The proposed hollow roof combined with the designed brick-cavity wall with brick projections and static sunshade lessened Indoor Air Temperature in summer and incr...
Yaolin Lin - One of the best experts on this subject based on the ideXlab platform.
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A new virtual sphere method for estimating the role of thermal mass in natural ventilated buildings
Energy and Buildings, 2011Co-Authors: Junli Zhou, Guoqiang Zhang, Yaolin Lin, Hanqing WangAbstract:The role of thermal mass is very important in natural ventilated buildings. Thermal mass can be classified as external thermal mass and internal thermal mass. In this paper, a heat balance model for naturally ventilated building is developed. The effect of external thermal mass is introduced by harmonic response method, and the effect of internal thermal mass is calculated by virtual sphere method which can lump different shapes and types into one virtual sphere. The effective convection heat transfer coefficient is presented to represents the effect of uneven distribution of internal thermal mass Temperature. Through comparison with Li's model [1] and numerical calculation, it was found that the model is more suitable than the others, especially in estimating decrement factor of Indoor Air Temperature. The errors of time lag become smaller when the fluctuation of Indoor Air Temperature is smaller. Based on the model, a simple tool is developed to evaluate the Indoor Air Temperature and required internal thermal mass for certain naturally ventilated buildings.
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coupling of thermal mass and natural ventilation in buildings
Energy and Buildings, 2008Co-Authors: Junli Zhou, Guoqiang Zhang, Yaolin LinAbstract:The coupling of thermal mass and natural ventilation is important to passive building design. Thermal mass can be classified as external thermal mass and internal thermal mass. Due to great diurnal variation of ambient Air Temperature and solar radiation intensity, heat transfer through building envelopes, which is called external thermal mass, is a complex and unsteady process. Indoor furniture are internal thermal mass, affecting the Indoor Air Temperature through the process of absorbing and releasing heat. In this paper, a heat balance model coupling the external and internal thermal mass, natural ventilation rate and Indoor Air Temperature for naturally ventilated building is developed. In this model, the inner surface Temperature of building envelopes is obtained based on the harmonic response method. The effect of external and internal thermal mass on Indoor Air Temperature for six external walls is discussed of different configurations including lightweight and heavy structures with and without external/internal insulation. Based on this model, a simple tool is developed to estimate the Indoor Air Temperature for certain external and internal thermal mass and to determine the internal thermal mass needed to maintain required Indoor Air Temperature for certain external wall for naturally ventilated building.
Meghana Charde - One of the best experts on this subject based on the ideXlab platform.
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COMPARATIVE THERMAL PERFORMANCE OF STATIC SUNSHADE AND BRICK CAVITY WALL FOR ENERGY EFFICIENT BUILDING ENVELOPE IN COMPOSITE CLIMATE
Thermal Science, 2014Co-Authors: Meghana Charde, Sourabh Bhati, Ayushman Kheterpal, Rajiv GuptaAbstract:Energy efficient building technologies can reduce energy consumption in buildings. In present paper effect of designed static sunshade, brick cavity wall with brick projections and their combined effect on Indoor Air Temperature has been analyzed by constructing three test rooms each of habitable dimensions (3.0 m × 4.0 m × 3.0 m) and studying hourly Temperatures on typical days for one month in summer and winter each. The three rooms have also been simulated using a software and the results have been compared with the experimental results. Designed static sunshade increased Indoor Air Temperature in winter while proposed brick cavity wall with brick projections lowered it in summer. Combined effect of building elements lowered Indoor Air Temperature in summer and increased it in winter as compared to outdoor Air Temperature. It is thus useful for energy conservation in buildings in composite climate.
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Effect of energy efficient building elements on summer cooling of buildings
Energy and Buildings, 2013Co-Authors: Meghana Charde, Rajiv GuptaAbstract:Abstract Growing energy demands with an increasing population have reiterated the importance of energy conservation. Buildings share a large portion of energy use worldwide. Energy efficient building technologies help to maximize solar heat gain in winter, minimize it in summer and optimize energy requirements in buildings. In present paper, effect of ventilated brick cavity wall with brick projections (independently and combined with designed static sunshade and hollow roof) on Indoor Air Temperature has been analyzed experimentally by constructing four rooms of habitable dimensions (3.0 m × 4.0 m × 3.0 m high) and studying average hourly Temperatures in summer. The combined effect of ventilated brick cavity wall with brick projections, designed static sunshade and hollow roof helped to lower Indoor Air Temperature for hotter part of the day in the study period. It also lowered maximum and minimum Indoor Air Temperature and swing in Indoor Air Temperature although there was a large variation in outdoor Air Temperature. Combined effect of the energy efficient building elements is thus useful for summer cooling and energy conservation in buildings.
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Annual Thermal Performance of a Hollow Roof in Combination with a Cavity Wall and Static Sunshade: Experimental Study of Energy-Efficient Rooms
Journal of Energy Engineering, 2013Co-Authors: Meghana Charde, Rajiv GuptaAbstract:AbstractEnergy consumption by the building sector constitutes a large portion of global energy use. Energy-efficient building technologies help to reduce heat gain in hot summer months, heat loss in cold winter months, and modify energy requirements in buildings. In the writers’ paper, the effect of a proposed hollow roof (independent of and combined with a designed brick-cavity wall with brick projections and static sunshade) on Indoor Air Temperature has been analyzed experimentally by constructing four rooms of habitable dimensions (3.0×4.0×3.0-m high) and studying average hourly Temperatures for 1 year. Each room has a different combination of type of roof, wall, and static sunshade; hence, the difference in Indoor Air Temperature of the rooms will primarily be attributable to differences in heat transferred through these building elements. The proposed hollow roof combined with the designed brick-cavity wall with brick projections and static sunshade lessened Indoor Air Temperature in summer and incr...
Junli Zhou - One of the best experts on this subject based on the ideXlab platform.
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A new virtual sphere method for estimating the role of thermal mass in natural ventilated buildings
Energy and Buildings, 2011Co-Authors: Junli Zhou, Guoqiang Zhang, Yaolin Lin, Hanqing WangAbstract:The role of thermal mass is very important in natural ventilated buildings. Thermal mass can be classified as external thermal mass and internal thermal mass. In this paper, a heat balance model for naturally ventilated building is developed. The effect of external thermal mass is introduced by harmonic response method, and the effect of internal thermal mass is calculated by virtual sphere method which can lump different shapes and types into one virtual sphere. The effective convection heat transfer coefficient is presented to represents the effect of uneven distribution of internal thermal mass Temperature. Through comparison with Li's model [1] and numerical calculation, it was found that the model is more suitable than the others, especially in estimating decrement factor of Indoor Air Temperature. The errors of time lag become smaller when the fluctuation of Indoor Air Temperature is smaller. Based on the model, a simple tool is developed to evaluate the Indoor Air Temperature and required internal thermal mass for certain naturally ventilated buildings.
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coupling of thermal mass and natural ventilation in buildings
Energy and Buildings, 2008Co-Authors: Junli Zhou, Guoqiang Zhang, Yaolin LinAbstract:The coupling of thermal mass and natural ventilation is important to passive building design. Thermal mass can be classified as external thermal mass and internal thermal mass. Due to great diurnal variation of ambient Air Temperature and solar radiation intensity, heat transfer through building envelopes, which is called external thermal mass, is a complex and unsteady process. Indoor furniture are internal thermal mass, affecting the Indoor Air Temperature through the process of absorbing and releasing heat. In this paper, a heat balance model coupling the external and internal thermal mass, natural ventilation rate and Indoor Air Temperature for naturally ventilated building is developed. In this model, the inner surface Temperature of building envelopes is obtained based on the harmonic response method. The effect of external and internal thermal mass on Indoor Air Temperature for six external walls is discussed of different configurations including lightweight and heavy structures with and without external/internal insulation. Based on this model, a simple tool is developed to estimate the Indoor Air Temperature for certain external and internal thermal mass and to determine the internal thermal mass needed to maintain required Indoor Air Temperature for certain external wall for naturally ventilated building.
