The Experts below are selected from a list of 108255 Experts worldwide ranked by ideXlab platform
Svend Svendsen - One of the best experts on this subject based on the ideXlab platform.
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Improved Control of Radiator Heating Systems with Thermostatic Radiator Valves without Pre-Setting Function
Energies, 2019Co-Authors: Theofanis Benakopoulos, Dirk Vanhoudt, Robbe Salenbien, Svend SvendsenAbstract:Low-Temperature district heating will play an important role in a future free of fossil fuels. This will only be able to be realized through the low-Temperature operation of heating systems in existing buildings. Existing radiator systems can operate with low Temperatures for most of the year because they are designed for extremely cold days, but errors have to be corrected and the control of the radiator systems needs to be improved. In this paper, we present a strategy to achieve low-Temperature operation from the radiator system of a multi-family building in Denmark without a pre-setting function in the thermostatic radiator valves. The strategy is based on operating the system with a combination of a minimum Supply Temperature and small Temperature differences over the radiators. The operation of the system is analyzed through a thermal-hydraulic model. A minimum Supply Temperature weather compensation curve was calculated and implemented in the central Supply Temperature control. Return Temperature measurements in the substation, the risers, and several critical radiators were performed before and after the implementation of the strategy. The measurements confirm that a lower Supply Temperature results in a reduction of the return Temperature. However, the system operator needs to be supported by a tool package to correctly maintain the system’s operation.
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Theoretical overview of heating power and necessary heating Supply Temperatures in typical Danish single-family houses from the 1900s
Energy and Buildings, 2016Co-Authors: Dorte Skaarup Østergaard, Svend SvendsenAbstract:Abstract As existing buildings are renovated and energy-efficiency measures are implemented to meet requirements for reduced energy consumption, it becomes easier to heat our homes with low-Temperature heating. This study set out to investigate how much the heating system Supply Temperature can be reduced in typical Danish single-family houses constructed in the 1900s. The study provides a simplified theoretical overview of typical building constructions and standards for the calculation of design heat loss and design heating power in Denmark in the 1900s. The heating power and heating demand in six typical Danish single-family houses constructed in the 1900s were estimated based on simple steady-state calculations. We found that the radiators in existing single-family houses should not necessarily be expected to be over-dimensioned compared to current design heat loss. However, there is considerable potential for using low-Temperature space heating in existing single-family houses in typical operation conditions. Older houses were not always found to require higher heating system Temperatures than newer houses. We found that when these houses have gone through reasonable energy renovations, most of them can be heated with a Supply Temperature below 50 °C for more than 97% of the year.
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Effects of boosting the Supply Temperature on pipe dimensions of low-energy district heating networks: A case study in Gladsaxe, Denmark
Energy and Buildings, 2015Co-Authors: Hakan İbrahim Tol, Svend SvendsenAbstract:Abstract This paper presents a method for the dimensioning of the low-energy District Heating (DH) piping networks operating with a control philosophy of Supplying heat in low-Temperature such as 55 °C in Supply and 25 °C in return regularly while the Supply Temperature levels are being boosted in cold winter periods. The performance of the existing radiators that were formerly sized with over-dimensions was analyzed, its results being used as input data for the performance evaluation of the piping network of the low-energy DH system operating with the control philosophy in question. The optimization method was performed under different mass flow limitations that were formed with various Temperature configurations. The results showed that reduction in the mass flow rate requirement of a district is possible by increasing the Supply Temperature in cold periods with significant reduction in heat loss from the DH network. Sensitivity analysis was carried out in order to evaluate the area of applicability of the proposed method. Hence varied values of the original capacity and the current capacity of the existing radiators were evaluated with the design Temperature values that were defined by two former radiator sizing standards.
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renewable based low Temperature district heating for existing buildings in various stages of refurbishment
Energy, 2013Co-Authors: Marek Brand, Svend SvendsenAbstract:Denmark is aiming for a fossil-free heating sector for buildings by 2035. Judging by the national heating plan, this will be achieved mainly by a further spread of DH (district heating) based on the renewable heat sources. To make the most cost-effective use of these sources, the DH Supply Temperature should be as low as possible. We used IDA–ICE software to simulate a typical Danish single-family house from the 1970s connected to DH at three different stages of envelope and space heating system refurbishment. We wanted to investigate how low the DH Supply Temperature can be without reducing the current high level of thermal comfort for occupants or the good efficiency of the DH network. Our results show that, for a typical single-family house from the 1970s, even a small refurbishment measure such as replacing the windows allows the reduction of the maximum DH Supply Temperature from 78 to 67 °C and, for 98% of the year, to below 60 °C. However for the Temperatures below 60 °C a low-Temperature DH substation is required for DHW (domestic hot water) heating. This research shows that renewable sources of heat can be integrated into the DH system without problems and contribute to the fossil-free heating sector already today.
Weicheng Xiong - One of the best experts on this subject based on the ideXlab platform.
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very low Temperature radiant heating cooling indoor end system for efficient use of renewable energies
Solar Energy, 2010Co-Authors: Yiping Wang, Congrong Wang, Weicheng XiongAbstract:Abstract Solar or solar-assisted space heating systems are becoming more and more popular. The solar energy utilization efficiency is high when the collector is coupled with indoor radiant heating suppliers, since in principle, lower Supply Temperature means lower demand Temperature and then the system heat loss is less. A new type radiant end system is put forward for even lower Supply Temperature compared to the conventional radiant floor heating systems. A three dimensional model was established to investigate its energy Supply capacities. Simulation results show that 50 W per meter length tube can be achieved with the medium Temperature of 30 °C for heating and 15 °C for cooling. The predicted results agree well with the actual data from a demonstration building. Furthermore, it is demonstrated that a Supply Temperature of 22 °C in winter and of 17 °C in summer already met the indoor requirements. The new end system has good prospects for effective use of local renewable resources.
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Very low Temperature radiant heating/cooling indoor end system for efficient use of renewable energies
Solar Energy, 2010Co-Authors: Jianbo Ren, Yiping Wang, Congrong Wang, Li Zhu, Weicheng XiongAbstract:Abstract Solar or solar-assisted space heating systems are becoming more and more popular. The solar energy utilization efficiency is high when the collector is coupled with indoor radiant heating suppliers, since in principle, lower Supply Temperature means lower demand Temperature and then the system heat loss is less. A new type radiant end system is put forward for even lower Supply Temperature compared to the conventional radiant floor heating systems. A three dimensional model was established to investigate its energy Supply capacities. Simulation results show that 50 W per meter length tube can be achieved with the medium Temperature of 30 °C for heating and 15 °C for cooling. The predicted results agree well with the actual data from a demonstration building. Furthermore, it is demonstrated that a Supply Temperature of 22 °C in winter and of 17 °C in summer already met the indoor requirements. The new end system has good prospects for effective use of local renewable resources.
Beungyong Park - One of the best experts on this subject based on the ideXlab platform.
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experimental and numerical study on the application of low Temperature radiant floor heating system with capillary tube thermal performance analysis
Applied Thermal Engineering, 2019Co-Authors: Beungyong ParkAbstract:Abstract This study is practice-based learning, investigated the thermal performance of the conventional Korea standard radiant floor heating system with polybutylene pipe (the Model with PB) and a low-Temperature with capillary tube (the Model with CT) in an experimental test and simulation model, analyzing the thermal environment based on the floor surface Temperature and indoor air Temperature distribution. A new method that analyzes the thermal performance of two different floor heating systems being matched simultaneous measurement were developed and applied. Results of the simulation analysis were verified by comparison with the results that achieved through an analysis using the same conditions as the experimental test performance evaluation. The results show that the Model with CT maintains floor surface Temperature more stable than the Model with PB under same hot water Supply Temperature condition. The standard deviation of floor surface Temperature was only 0.5–0.6 °C for the Model with CT, showing that it had a very uniform distribution. The Model with PB had three times more initial response time toward intermittent operation compared to the Model with CT for the initial indoor air Temperature to rise by 4 °C. The Model with CT showed a 12.1% and 9.2% increase in thermal performance at hot water Supply Temperatures of 55 °C and 40 °C, respectively, compared to the Model with PB. The thermal comfort (PMV, PPD) from the Model with CT at a hot water Supply Temperature of 40 °C is better than that of the Model with PB at a hot water Supply Temperature of 55 °C. Further research remains necessary to analyze long-term behavior and performance of this system. The differences and special features of this experimental study is that two different forms of floor heating systems were evaluated based on the same location of the equipment and the same heating load. A verified simulation model was then used to analyze the changes in heating effect while changing the depth of the embedded capillary tubes.
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Thermal Performance Evaluation of a Data Center Cooling System under Fault Conditions
Energies, 2019Co-Authors: Jinkyun Cho, Beungyong Park, Yongdae JeongAbstract:If a data center experiences a system outage or fault conditions, it becomes difficult to provide a stable and continuous information technology (IT) service. Therefore, it is critical to design and implement a backup system so that stability can be maintained even in emergency (unforeseen) situations. In this study, an actual 20 MW data center project was analyzed to evaluate the thermal performance of an IT server room during a cooling system outage under six fault conditions. In addition, a method of organizing and systematically managing operational stability and energy efficiency verification was identified for data center construction in accordance with the commissioning process. Up to a chilled water Supply Temperature of 17 °C and a computer room air handling unit air Supply Temperature of 24 °C, the Temperature of the air flowing into the IT server room fell into the allowable range specified by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers standard (18–27 °C). It was possible to perform allowable operations for approximately 320 s after cooling system outage. Starting at a chilled water Supply Temperature of 18 °C and an air Supply Temperature of 25 °C, a rapid Temperature increase occurred, which is a serious cause of IT equipment failure. Due to the use of cold aisle containment and designs with relatively high chilled water and air Supply Temperatures, there is a high possibility that a rapid Temperature increase inside an IT server room will occur during a cooling system outage. Thus, the backup system must be activated within 300 s. It is essential to understand the operational characteristics of data centers and design optimal cooling systems to ensure the reliability of high-density data centers. In particular, it is necessary to consider these physical results and to perform an integrated review of the time required for emergency cooling equipment to operate as well as the backup system availability time.
Luigi Glielmo - One of the best experts on this subject based on the ideXlab platform.
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model predictive control based optimal operations of district heating system with thermal energy storage and flexible loads
IEEE Transactions on Automation Science and Engineering, 2017Co-Authors: Francesca Verrilli, Seshadhri Srinivasan, Giovanni Gambino, Michele Canelli, Mikko Himanka, Carmen Del Vecchio, Maurizio Sasso, Luigi GlielmoAbstract:Operating heating power plant (DHPP) with fluctuating load is a complex problem. Thermal energy storage (TES), flexible loads, and operating constraints compound this complexity further. This investigation focuses on the design of a model predictive controller (MPC) that reduces the operating and maintenance cost in a DHPP, considering TES and flexible loads. The MPC accomplishes this task by scheduling boilers, TES units, and flexible loads. To handle the fluctuating demand, the MPC uses forecasts and combines it with a constrained optimization problem. The objective function reflects the cost, whereas the generator limits, TES dynamics, thermal loads, including Supply Temperature, power plant layout, and reliability, are the constraints. The resulting optimization problem is modeled as a mixed-integer linear program with both continuous and logic variables. Here the logic variables model the operating modes of the boiler and storage units. The use of receding horizon approach enhances the robustness to the forecast errors. The constraints modeling plant layout, Supply Temperature, and grid reliability lead to a more realistic solution. The MPC is illustrated using simulation on historical data and experiments on a DHPP at Ylivieska, Finland. Our results demonstrate the cost benefits of the proposed approach.
Robbe Salenbien - One of the best experts on this subject based on the ideXlab platform.
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Improved Control of Radiator Heating Systems with Thermostatic Radiator Valves without Pre-Setting Function
Energies, 2019Co-Authors: Theofanis Benakopoulos, Dirk Vanhoudt, Robbe Salenbien, Svend SvendsenAbstract:Low-Temperature district heating will play an important role in a future free of fossil fuels. This will only be able to be realized through the low-Temperature operation of heating systems in existing buildings. Existing radiator systems can operate with low Temperatures for most of the year because they are designed for extremely cold days, but errors have to be corrected and the control of the radiator systems needs to be improved. In this paper, we present a strategy to achieve low-Temperature operation from the radiator system of a multi-family building in Denmark without a pre-setting function in the thermostatic radiator valves. The strategy is based on operating the system with a combination of a minimum Supply Temperature and small Temperature differences over the radiators. The operation of the system is analyzed through a thermal-hydraulic model. A minimum Supply Temperature weather compensation curve was calculated and implemented in the central Supply Temperature control. Return Temperature measurements in the substation, the risers, and several critical radiators were performed before and after the implementation of the strategy. The measurements confirm that a lower Supply Temperature results in a reduction of the return Temperature. However, the system operator needs to be supported by a tool package to correctly maintain the system’s operation.
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Evaluation of the return Temperature reduction potential of optimized substation control
Energy Procedia, 2018Co-Authors: Tijs Van Oevelen, Dirk Vanhoudt, Robbe SalenbienAbstract:Abstract Network Temperatures play a major role in the overall efficiency of district heating networks. Low network Temperatures are desirable, because they allow high heat production efficiency and low network heat losses. Furthermore, low network Temperatures benefit the injection of low-Temperature renewable and excess heat sources. At the same time, a high Temperature difference between Supply and return pipes is desired to limit the network flow rate. This reduces pumping power and increases the network capacity. Whereas the network Supply Temperature is governed by the heat Supply, the network return Temperature is determined by the connected customers. This paper focuses on an approach for reducing the network return Temperature by considering the control of district heating substations for space heating. Optimal heating control curves exist for the secondary-side Supply Temperature and flow rate that minimize the network return Temperature of indirect substations. The goal is to investigate the impact of optimized control curves on the network return Temperature, under various circumstances. Using a steady-state model of an indirect substation connected to a radiator system, the optimal control strategy is calculated. Its performance is compared to that of traditional control using a pre-set heating curve. The results show that the biggest impact occurs in partial-load conditions, with a potential for reducing the network return Temperature by up to 9.9 °C (average 6.0 °C) and primary flow rate reduction up to 14.7 % (average 7.6 %). A parametric analysis to evaluate the impact of the network Supply Temperature, heat demand and heating system design sizing is presented. It is concluded that the use of optimized substation control for space heating could significantly reduce the network return Temperature and primary flow rate. This would benefit the overall energetic system performance of district heating grids.
