The Experts below are selected from a list of 1155 Experts worldwide ranked by ideXlab platform

Joachim Claesson - One of the best experts on this subject based on the ideXlab platform.

  • The influence of energy conservation on the performance of solar thermal systems - A cold country case study
    Energy Procedia, 2012
    Co-Authors: Jörgen Wallin, Diane Bastien, Joachim Claesson
    Abstract:

    The European Union has set a goal that the energy use in the built environment shall be reduced by 41 % to the year 2050 compared to 2005-2006. This could introduce new opportunities for solar thermal systems in cold countries. In such countries, like Sweden and Canada, the economy in solar thermal collector installation projects is often spoiled by the fact that most of heating energy Demand of the building occurs during periods when the available solar energy is low. The present paper investigates the performance of solar thermal systems subjected to different quota between space heating and domestic Hot Water Demand (DHW). This study investigates the performance of a solar thermal system integrated to four different buildings with varying heating loads in two different locations, Sweden and Canada. Models of single family houses are created which are able to simulate the total heating Demand with different heating Demand profiles but the same DHW Demand. Simulations are performed in TRNSYS, an advanced tool used to simulate transient systems. Results indicate that solar combisystems tend to generate more useful energy and therefore be more cost effective when installed in buildings with higher heating Demands. © 2012 The Authors.

Ryohei Yokoyama - One of the best experts on this subject based on the ideXlab platform.

  • development of a domestic Hot Water Demand prediction model based on a bottom up approach for residential energy management systems
    Applied Thermal Engineering, 2016
    Co-Authors: Tetsuya Wakui, Ryohei Yokoyama
    Abstract:

    Abstract An energy management system (EMS) that controls energy equipment in residential dwellings contributes to energy conservation and cost reduction. A Hot energy Demand prediction method is necessary for the EMS to provide the best possible performance. A prediction method using a bottom-up approach based on end-use analysis with detailed energy consumption measurement was developed. One of the advantages of the proposed prediction method is that it provides good accuracy without needing large computational resources. Since the method is based on end-use analysis, the EMS can revise the prediction and controls when necessary. The performance of the developed prediction method was evaluated by comparing it with results produced by support vector regression. An operational simulation was performed to evaluate performance in a more practical environment. The simulation indicated that the proposed method showed the best performance.

  • Performance Estimation and Optimal Operation of a CO2 Heat Pump Water Heating System
    International Journal of Thermodynamics, 2013
    Co-Authors: Ryohei Yokoyama
    Abstract:

    The daily performance of a CO2 heat pump Water heating system with a Hot Water storage tank is affected by the history of daily Hot Water Demand and heat pump operating conditions. To attain the maximum system performance, it is important to estimate the daily changes in the system performance values accurately in relation to those in Hot Water Demand and heat pump operating conditions, and determine the operating conditions optimally based on the estimation. In this paper, neural network models are used for this estimation, and the values of model parameters are identified by a global optimization method. In addition, the outlet Water temperature for during operation and the inlet Water temperature for shutdown are determined to maximize the system efficiency subject to a lower limit for the volume of unused Hot Water. The validity and effectiveness of this approach are ascertained by a numerical study using a simulated Hot Water Demand.

  • Performance analysis of a CO2 heat pump Water heating system under a daily change in a standardized Demand
    Energy, 2010
    Co-Authors: Ryohei Yokoyama, Tetsuya Wakui, Junya Kamakari, Kazuhisa Takemura
    Abstract:

    Air-to-Water heat pumps using CO2 as a natural refrigerant have been developed and commercialized. They are expected to contribute to energy saving in residential Hot Water supply. The objective of the research is to analyze the performance of a Water heating system composed of a CO2 heat pump and a Hot Water storage tank by numerical simulation. In this paper, the system performance is analyzed under a daily change in a standardized Hot Water Demand, and some features of the temperature distribution in the storage tank and the system performance criteria such as coefficient of performance, storage and system efficiencies, and volumes of stored and unused Hot Water are investigated. It turns out that the daily change in the Hot Water Demand does not significantly affect the daily averages of the COP, and storage and system efficiencies, while it significantly affects not only the daily change in the volume of Hot Water unused after the tapping mode, but also that in the volume of Hot Water stored after the charging mode. The influence of the daily change in the Hot Water Demand on the volumes of stored and unused Hot Water is clarified quantitatively.

  • Influence of Operation Temperatures on Performance of a CO2 Heat Pump Water Heating System
    Journal of Environment and Engineering, 2008
    Co-Authors: Ryohei Yokoyama, Tetsuya Wakui, Shinsuke Okagaki, Kazuhisa Takemura
    Abstract:

    An air-to-Water CO2 heat pump is used in combination with a domestic Hot Water storage tank, and the performance of this Water heating system is affected significantly not only by instantaneous ambient air and city Water temperatures but also by hourly changes in domestic Hot Water Demand and temperature distribution in the storage tank. In this paper, the influence of operation conditions such as outlet Water temperature during operation and inlet Water temperature for shutdown of a CO2 heat pump on the performance of a Water heating system is investigated by numerical simulation. The trade-off relationship between the system efficiency and the volume of unused domestic Hot Water as criteria for the system performance is clarified in relation to the operation conditions. The influence of seasonal changes in ambient air and city Water temperatures on the trade-off relationship is also clarified.

Giedre Streckiene - One of the best experts on this subject based on the ideXlab platform.

  • Solar assisted ground source heat pump performance in nearly zero energy building in Baltic countries
    Environmental and Climate Technologies, 2013
    Co-Authors: K Januševičius, Giedre Streckiene
    Abstract:

    In near zero energy buildings (NZEB) built in Baltic countries, heat production systems meet the challenge of large share domestic Hot Water Demand and high required heating capacity. Due to passive solar design, cooling Demand in residential buildings also needs an assessment and solution. Heat pump systems are a widespread solution to reduce energy use. A combination of heat pump and solar thermal collectors helps to meet standard requirements and increases the share of renewable energy use in total energy balance of country. The presented paper describes a simulation study of solar assisted heat pump systems carried out in TRNSYS. The purpose of this simulation was to investigate how the performance of a solar assisted heat pump combination varies in near zero energy building. Results of three systems were compared to autonomous (independent) systems simulated performance. Different solar assisted heat pump design solutions with serial and parallel solar thermal collector connections to the heat pump loop were modelled and a passive cooling possibility was assessed. Simulations were performed for three Baltic countries: Lithuania, Latvia and Estonia.

Kwee Tiang Chew - One of the best experts on this subject based on the ideXlab platform.

  • Improving the Operation of Solar Water Heating Systems in Green Buildings via Optimized Control Strategies
    IEEE Transactions on Industrial Informatics, 2018
    Co-Authors: Wen-tai Li, Kannan Thirugnanam, Wayes Tushar, Chau Yuen, Kwee Tiang Chew
    Abstract:

    Solar Water heating (SWH) systems are well known and effective structures that transfer solar energy into thermal energy with Hot Water as the storage. The efficiency of an SWH system is mainly based on well-designed solar collectors and proper operation mechanisms. Although the most existing literature has focused on the efficiency enhancement of solar collectors, limited studies are devoted to improve the operating mechanism. As such, this paper studies the control mechanisms of the SWH system with a purpose so as to help the building manager to achieve targeted energy management goals. In particular, three control approaches are presented for improving the operational efficiency of the SWH system by controlling auxiliary heaters, such as heat pumps, electric heaters, and circulation pumps. The proposed approaches are developed based on different requirements of information such as the Hot Water Demand, weather, and electricity price. Moreover, three various energy management objectives are studied with considering different scenarios in terms of real weather pattern and Hot Water Demand of a commercial building. The results validate that the proposed approaches can improve the operation of the SWH system according to various operation objectives.

Shanshan Wang - One of the best experts on this subject based on the ideXlab platform.

  • study on Demand side design parameters of solar domestic Hot Water system in residential buildings
    Energy Procedia, 2015
    Co-Authors: Xilin Chen, Weiye Zhou, Shanshan Wang
    Abstract:

    Abstract Solar domestic Hot Water system is widely used and developing fast in recent years in China. However many problems occur at the same time, for example more energy consumption by circulation pump, Water reheating, long investment payback period, and etc. Through analyzing the field-testing data of projects and investigating of different residential consumers, it was found that compared to actual Hot Water consumption the solar domestic Hot Water systems were generally designed too large in capacity, which means the designed Hot Water Demand is much greater than actual user consumption. This study compared different specifications and recommended design parameters value of Hot Water related standards, and analyzed the calculation methodology and design parameter ofHot Water quota. Finally problems in the system design are summarized and suggestions are proposed for designers and different stakeholders.