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T T Chow - One of the best experts on this subject based on the ideXlab platform.

  • optimization of distribution piping network in District Cooling system using genetic algorithm with local search
    Energy Conversion and Management, 2007
    Co-Authors: Apple L S Cha, V I Hanby, T T Chow
    Abstract:

    A District Cooling system is a sustainable means of distribution of Cooling energy through mass production. A Cooling medium like chilled water is generated at a central refrigeration plant and supplied to serve a group of consumer buildings through a piping network. Because of the substantial capital investment involved, an optimal design of the distribution piping configuration is one of the crucial factors for successful implementation of the District Cooling scheme. In the present study, genetic algorithm (GA) incorporated with local search techniques was developed to find the optimal/near optimal configuration of the piping network in a hypothetical site. The effect of local search, mutation rate and frequency of local search on the performance of the GA in terms of both solution quality and computation time were investigated and presented in this paper.

  • performance evaluation of District Cooling plant with ice storage
    Energy, 2006
    Co-Authors: Apple L S Chan, T T Chow, Square K F Fong, John Z Lin
    Abstract:

    District Cooling system (DCS) is a massive Cooling energy production scheme that serves a group of buildings. The system performance can often be improved by the incorporation of a cool-storage system, in that part of the Cooling demand is shifted from peak hours to non-peak hours. This brings mutual benefits to the power supplier and the consumers. In order to evaluate the energy performance and cost effectiveness of such an integrated technology, a feasible District Cooling plus ice-storage system was developed for a hypothetical site in Hong Kong. A parametric study making use of the DOE-2 and TRNSYS simulation software was conducted to evaluate the system performance at different partial storage capacities, control strategies, and tariff structures. Other than the basic design factors, the results from 27 cases showed the importance of the tariff structure, the capital and electricity costs in this issue.

  • energy modelling of District Cooling system for new urban development
    Energy and Buildings, 2004
    Co-Authors: T T Chow, Apple L S Chan, W H Au, K.f. Fong, Vincent Cheng
    Abstract:

    District Cooling technology is advantageous in warm and hot climatic regions, in that chilled water from a central refrigeration plant is delivered through a distribution network to groups of buildings. The technology is most suitable for new urban developments where system design and construction receive much freedom. With a focus on the energy use, this paper outlines an energy modelling methodology and decision approach to derive the most desirable scheme for a given project. The process involves a series of building design load computation, dynamic simulation, and plant energy consumption analyses for different phases of development. A proposed scheme for the South East Kowloon Development Project in Hong Kong is quoted as an example to illustrate the approach.

  • building mix optimization in District Cooling system implementation
    Applied Energy, 2004
    Co-Authors: T T Chow, Apple L S Cha, C L Song
    Abstract:

    A District-Cooling system (DCS) has been applied in a number of countries where chilled water from a central plant is delivered through a distribution network to groups of buildings in an urban District. Because of the expected considerable investment and lengthy payback period, well-planned and optimized system design and operation are crucial areas leading to the success of the implementation. Much saving can be achieved when the plant serves a group of buildings with diversifying daily Cooling-load patterns. Among various design factors and solution schemes, one important planning decision is therefore to determine the desirable mix of building types, within the District of interest, to be served by the DCS. An approach to determine this optimal mix through the use of genetic algorithm (GA) was described in this paper. The thermal-load modeling technique and the objective function for optimization were derived. The case studies showed that the method was effective to give optimal or near-optimal solutions.

Antonio Giovanni Perdichizzi - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of Solar District Cooling systems: the Effect of Heat Rejection
    E3S Web of Conferences, 2020
    Co-Authors: Giovanni Brumana, Giuseppe Franchini, Elisa Ghirardi, Antonio Giovanni Perdichizzi
    Abstract:

    The paper presents the performance assessment of a solar District Cooling system with special attention to the heat rejection process. The investigation includes energetic, economic and environmental aspects. The District Cooling network is driven by two-stage Li-Br absorption chillers coupled with parabolic trough solar collectors. The whole system, including solar field, storage tanks and chilled water pipeline, has been modelled in Trnsys. The focus is on the heat rejection systems, and their impact on the performance of the Cooling plant. Four different types of heat rejection systems are considered: Air Cooling (AC), Evaporative Cooling Tower (ECT), Groundwater Heat Exchanger (GHE) and Geothermal Boreholes (GB). The paper presents two case studies in the Gulf region: the warm climate is compared for two condition of humidity, dry (Riyadh) and humid (Abu Dhabi). Furthermore, the work presents a multivariable optimization procedure based on GenOpt software interacting with Trnsys model under the constraint of a 70% annual solar fraction. The best option resulted to be the one based on absorption chillers coupled with Groundwater Heat Exchanger in both locations. The annual power consumption is reduced by 83% in Abu Dhabi and 82% in Riyadh compared to conventional Cooling systems.

  • performance prediction of a solar District Cooling system in riyadh saudi arabia a case study
    Energy Conversion and Management, 2018
    Co-Authors: Genoveffa Franchini, Giovanni Umana, Antonio Giovanni Perdichizzi
    Abstract:

    Abstract The present paper aims to evaluate the performance of a solar District Cooling system in typical Middle East climate conditions. A centralized Cooling station is supposed to distribute chilled water for a residential compound through a piping network. Two different solar Cooling technologies are compared: two-stage lithium-bromide absorption chiller (2sABS) driven by Parabolic Trough Collectors (PTCs) vs. single-stage lithium-bromide absorption chiller (1sABS) fed by Evacuated Tube Collectors (ETCs). A computer code has been developed in Trnsys® (the transient simulation software developed by the University of Wisconsin) to simulate on hourly basis the annual operation of the solar Cooling system, including building thermal load calculation, thermal losses in pipes and control strategy of the energy storage. A solar fraction of 70% was considered to size the solar field aperture area and the chiller capacity, within a multi-variable optimization process. An auxiliary compression chiller is supposed to cover the peak loads and to be used as backup unit. The two different solar Cooling plants exhibit strongly different performance. For each plant configuration, the model determined the optimal size of every component leading to the primary cost minimization. The solar District Cooling configuration based on 2sABS and PTCs shows higher performance at Riyadh (KSA) climate conditions and the overall cost is 30% lower than the one of the single-stage absorption chiller plant.

  • peak shaving strategy through a solar combined Cooling and power system in remote hot climate areas
    Applied Energy, 2015
    Co-Authors: Antonio Giovanni Perdichizzi, Giuseppe Franchini, Giovanna Barigozzi, Silvia Ravelli
    Abstract:

    Abstract An effective combination of District Cooling with electric power production in an integrated solar combined cycle is presented and evaluated. A remote area in hot climate is assumed as location to highlight the importance of peak shaving strategy in an isolated or weakly interconnected power system. Two solutions for handling peak power demand are taken into account in the present investigation. On the one hand, the integration of a Concentrated Solar Power system (CSP) with a combined cycle power plant is considered to match peak power demand on the grid. On the other hand, the adoption of a District Cooling system where Cooling energy is produced by absorption chillers is proposed, instead of mechanical refrigeration, to reduce and flatten the load profile. The case study refers to a combined cycle (CC) based on a 46 MW Siemens SGT-800 gas turbine. The CC plant is integrated with a parabolic trough collectors (PTC) solar field and double-effect steam driven absorption chillers feeding a District Cooling network. The solar combined Cooling and power (SCCP) system is designed to operate in “island mode” to match both electrical and Cooling demand on an hourly basis, on a typical winter and summer day. A modeling procedure is applied to accurately simulate the plant operation, including off-design behavior of all plant components. During the day the solar source has the highest priority, whilst the gas turbine (GT) is operated at part-load to follow the load profile. Electric efficiency and fuel savings for the SCCP plant are computed and compared against the ones resulting from a conventional pure fossil system based on analogous combined cycle and compression refrigeration units. Results show that a SCCP system can significantly reduce fossil fuel consumption in both summer and winter peak hours, while providing higher overall efficiency through the whole day, both in summer and winter.

Yoonpyo Lee - One of the best experts on this subject based on the ideXlab platform.

  • feasibility of ice slurry application to the District Cooling system in korea
    International Journal of Air-conditioning and Refrigeration, 2014
    Co-Authors: Jae Dong Chung, Yoonpyo Lee, Jaeheo Lee, Changju Lee, Seungjae Moo, Hoseo Yoo
    Abstract:

    The District-Cooling system (DCS) has been in service in Sang-am in Seoul, Korea since 2005. The capacity of the DCS facility in Sang-am was 111 Gcal/h in 2011, and an additional 63 Gcal/h capacity is planned for installation by 2025. However, the Cooling demand has increased due to unexpected high-rise building blocks, and the required facility capacity is expected to be 101 Gcal/h. Adding a new building plan to the existing plant is difficult. This study centers on a feasibility study for the new requirement under the restrictions of existing pipelines, limited space and regulations on the use of electric-driven chillers in Korea, etc. The precise estimation of the diversity factor is essential to determine the required capacities. To this end, each building in the District area was categorized, and the Cooling loads were measured for the summer seasons of 2010 and 2011. The large energy capacity of an ice-slurry can potentially increase the Cooling capacity in existing plants while maintaining the same flow rate and pumping power. Thus introducing an ice-slurry is expected to be a potential solution to the significantly increased Cooling load under the restriction of existing pipeline system without requiring increases in pipe size or system flow rates.

  • feasibility study for ice slurry to District Cooling system in korea
    International Conference on Fuel Cell Science Engineering and Technology FUELCELL Collocated with ASME International Conference on Energy Sustainabili, 2013
    Co-Authors: Jae Dong Chung, Yoonpyo Lee, Hoseo Yoo, Jaeheo Lee, Changju Lee, Seungjae Moo
    Abstract:

    The District-Cooling system (DCS) was in service in Sang-am in Seoul, Korea after 2005. The facility capacity of the DCS in Sang-am is 111Gcal/h at 2011 and 63Gcal/h of facility is planned to install till 2025. However, the Cooling demand is increased due to new high-rise building blocks, and the required facility capacity is expected to be 101Gcal/h. A difficulty comes from building new plan in the existing plant. This paper is on the feasibility study for the new requirement under the restrictions of existing pipeline, limited space and regulation on the usage of electric driven chiller. Precise estimation of the diversity factor is essential to determine the required capacities. For this, every building in the area was categorized and the Cooling loads were measured for the summer seasons of 2010 and 2011. The large energy capacity of ice slurry can potentially increase the Cooling capacity in existing plants while maintaining the same flow rate and pumping power. Thus under the restriction of existing pipeline system, introducing ice slurry is expected as potential solution to the significantly increased Cooling load without requiring increases in pipe size or system flow rates.Copyright © 2013 by ASME

  • a field application case of the direct ice slurry transporting system for District Cooling
    International Journal of Air-conditioning and Refrigeration, 2010
    Co-Authors: Hoseo Yoo, Sang Hoo Lee, Yoonpyo Lee
    Abstract:

    In order to investigate the feasibility of the direct ice slurry transporting system for the purpose of District Cooling, a case study of field application is performed. The research aims to include the field measurement of ice packing factor, the performance of cold energy delivery, and the branching characteristics of ice slurry in which the additive is propylene glycol wt 10%. Two representative types of pipe branch are dealt with in this work. For the slurry flow with ice volume fraction of 0.16 or less, the pipe blocking due to aggregation is not observed. It is confirmed that the mass flow rate of ice slurry per unit Cooling load markedly decreases with the increase of the ice content. The pumping power also decreases, but remains unchanged when the ice fractions are higher than a certain level.

Hoseo Yoo - One of the best experts on this subject based on the ideXlab platform.

  • feasibility of ice slurry application to the District Cooling system in korea
    International Journal of Air-conditioning and Refrigeration, 2014
    Co-Authors: Jae Dong Chung, Yoonpyo Lee, Jaeheo Lee, Changju Lee, Seungjae Moo, Hoseo Yoo
    Abstract:

    The District-Cooling system (DCS) has been in service in Sang-am in Seoul, Korea since 2005. The capacity of the DCS facility in Sang-am was 111 Gcal/h in 2011, and an additional 63 Gcal/h capacity is planned for installation by 2025. However, the Cooling demand has increased due to unexpected high-rise building blocks, and the required facility capacity is expected to be 101 Gcal/h. Adding a new building plan to the existing plant is difficult. This study centers on a feasibility study for the new requirement under the restrictions of existing pipelines, limited space and regulations on the use of electric-driven chillers in Korea, etc. The precise estimation of the diversity factor is essential to determine the required capacities. To this end, each building in the District area was categorized, and the Cooling loads were measured for the summer seasons of 2010 and 2011. The large energy capacity of an ice-slurry can potentially increase the Cooling capacity in existing plants while maintaining the same flow rate and pumping power. Thus introducing an ice-slurry is expected to be a potential solution to the significantly increased Cooling load under the restriction of existing pipeline system without requiring increases in pipe size or system flow rates.

  • feasibility study for ice slurry to District Cooling system in korea
    International Conference on Fuel Cell Science Engineering and Technology FUELCELL Collocated with ASME International Conference on Energy Sustainabili, 2013
    Co-Authors: Jae Dong Chung, Yoonpyo Lee, Hoseo Yoo, Jaeheo Lee, Changju Lee, Seungjae Moo
    Abstract:

    The District-Cooling system (DCS) was in service in Sang-am in Seoul, Korea after 2005. The facility capacity of the DCS in Sang-am is 111Gcal/h at 2011 and 63Gcal/h of facility is planned to install till 2025. However, the Cooling demand is increased due to new high-rise building blocks, and the required facility capacity is expected to be 101Gcal/h. A difficulty comes from building new plan in the existing plant. This paper is on the feasibility study for the new requirement under the restrictions of existing pipeline, limited space and regulation on the usage of electric driven chiller. Precise estimation of the diversity factor is essential to determine the required capacities. For this, every building in the area was categorized and the Cooling loads were measured for the summer seasons of 2010 and 2011. The large energy capacity of ice slurry can potentially increase the Cooling capacity in existing plants while maintaining the same flow rate and pumping power. Thus under the restriction of existing pipeline system, introducing ice slurry is expected as potential solution to the significantly increased Cooling load without requiring increases in pipe size or system flow rates.Copyright © 2013 by ASME

  • a field application case of the direct ice slurry transporting system for District Cooling
    International Journal of Air-conditioning and Refrigeration, 2010
    Co-Authors: Hoseo Yoo, Sang Hoo Lee, Yoonpyo Lee
    Abstract:

    In order to investigate the feasibility of the direct ice slurry transporting system for the purpose of District Cooling, a case study of field application is performed. The research aims to include the field measurement of ice packing factor, the performance of cold energy delivery, and the branching characteristics of ice slurry in which the additive is propylene glycol wt 10%. Two representative types of pipe branch are dealt with in this work. For the slurry flow with ice volume fraction of 0.16 or less, the pipe blocking due to aggregation is not observed. It is confirmed that the mass flow rate of ice slurry per unit Cooling load markedly decreases with the increase of the ice content. The pumping power also decreases, but remains unchanged when the ice fractions are higher than a certain level.

Yong Min - One of the best experts on this subject based on the ideXlab platform.

  • Study of operation strategies for integrating ice-storage District Cooling systems into power dispatch for large-scale hydropower utilization
    Applied Energy, 2020
    Co-Authors: Ling Hao, Mingshan Wei, Xiaochen Yang, Panpan Song, Jia Meng, Yong Min
    Abstract:

    Abstract Hydropower curtailment for the run-of-over stations has become serious in Southwest China. The ice-storage District Cooling system is believed as an effective approach to provide flexibility for hydropower utilization. However, the existing ice-storage operation strategies in demand-side management cause that the ice storage cannot be adjusted in real-time to match the surplus hydropower, which brings difficulties for large-scale hydropower utilization. Therefore, this paper proposed the integration of ice-storage District Cooling systems into power dispatch based on smart grid. Two operation strategies were developed for the integration to achieve power supply-side management of ice-storage District Cooling system. One is the new ice-storage power-linked operation strategy, which was proposed to determine the ice storing/ melting capacity in the power dispatch. The other one is the Cooling pipelines dynamic-characteristics-considered operation strategy, which was applied in the power dispatch. The dynamic characteristics were calculated based on a linear model to be compatible with the linear constraints in power dispatch models. Finally, effects of two strategies were studied by taking scenes in Chongqing as the example. Results showed that the application of the first strategy only reduces the hydropower curtailment frequency, while application of the second strategy reduces both the curtailment frequency and amount. Furthermore, the simultaneous applications of the above two strategies enhance hydropower consumption by 7.5% (200 million kW·h) and reduce carbon emission by 7.4% (34,000 tons) every year. In addition, there exists an optimal total ice-storage capacity per day, i.e. 8600 MW·h, under which the system’s performance reaches the highest value.