The Experts below are selected from a list of 6519 Experts worldwide ranked by ideXlab platform
Stasa Borovic - One of the best experts on this subject based on the ideXlab platform.
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impact of grout thermal conductivity on the long term efficiency of the ground source heat pump system
Sustainable Cities and Society, 2017Co-Authors: Tomislav Kurevija, Marija Macenic, Stasa BorovicAbstract:Abstract Quality cementation of a borehole heat exchanger is often considered to be important parameter when analysing long-term heat pump efficiency. Implementing low conductivity grout leads to an increase of borehole thermal resistance and poor heat transfer. This paper analyses one real Retrofit Project which comprises of 16 borehole heat exchangers with thermal enhanced grout completion. Novel approach of testing the borehole heat exchanger was implemented, so called Steady-State Thermal Response Step Testing, which incorporate series of power steps to determine borehole capacity at steady-state heat transfer conditions and thermogeological properties of ground. Paper objective was to quantify what is real benefit by implementing more expensive thermal enhanced grout, compared to traditional bentonite, silica-sand grouts. Simulation of borehole temperatures and coefficient of performance (COP) changes over time was carried out with Ground Loop Design (GLD), taking into account four different grout mixes. Results shown that in thermogeological environment with mediocre thermal conductivity, distinction in COP was modest for each of the four analysed grouting material during 30 years. Comparing investment costs with savings in electricity for each grout mix case, conclusion is that there is no real benefit of implementing enhanced grout in mediocre thermal conductivity environment such as marly-clays.
Tomislav Kurevija - One of the best experts on this subject based on the ideXlab platform.
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impact of grout thermal conductivity on the long term efficiency of the ground source heat pump system
Sustainable Cities and Society, 2017Co-Authors: Tomislav Kurevija, Marija Macenic, Stasa BorovicAbstract:Abstract Quality cementation of a borehole heat exchanger is often considered to be important parameter when analysing long-term heat pump efficiency. Implementing low conductivity grout leads to an increase of borehole thermal resistance and poor heat transfer. This paper analyses one real Retrofit Project which comprises of 16 borehole heat exchangers with thermal enhanced grout completion. Novel approach of testing the borehole heat exchanger was implemented, so called Steady-State Thermal Response Step Testing, which incorporate series of power steps to determine borehole capacity at steady-state heat transfer conditions and thermogeological properties of ground. Paper objective was to quantify what is real benefit by implementing more expensive thermal enhanced grout, compared to traditional bentonite, silica-sand grouts. Simulation of borehole temperatures and coefficient of performance (COP) changes over time was carried out with Ground Loop Design (GLD), taking into account four different grout mixes. Results shown that in thermogeological environment with mediocre thermal conductivity, distinction in COP was modest for each of the four analysed grouting material during 30 years. Comparing investment costs with savings in electricity for each grout mix case, conclusion is that there is no real benefit of implementing enhanced grout in mediocre thermal conductivity environment such as marly-clays.
Marija Macenic - One of the best experts on this subject based on the ideXlab platform.
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impact of grout thermal conductivity on the long term efficiency of the ground source heat pump system
Sustainable Cities and Society, 2017Co-Authors: Tomislav Kurevija, Marija Macenic, Stasa BorovicAbstract:Abstract Quality cementation of a borehole heat exchanger is often considered to be important parameter when analysing long-term heat pump efficiency. Implementing low conductivity grout leads to an increase of borehole thermal resistance and poor heat transfer. This paper analyses one real Retrofit Project which comprises of 16 borehole heat exchangers with thermal enhanced grout completion. Novel approach of testing the borehole heat exchanger was implemented, so called Steady-State Thermal Response Step Testing, which incorporate series of power steps to determine borehole capacity at steady-state heat transfer conditions and thermogeological properties of ground. Paper objective was to quantify what is real benefit by implementing more expensive thermal enhanced grout, compared to traditional bentonite, silica-sand grouts. Simulation of borehole temperatures and coefficient of performance (COP) changes over time was carried out with Ground Loop Design (GLD), taking into account four different grout mixes. Results shown that in thermogeological environment with mediocre thermal conductivity, distinction in COP was modest for each of the four analysed grouting material during 30 years. Comparing investment costs with savings in electricity for each grout mix case, conclusion is that there is no real benefit of implementing enhanced grout in mediocre thermal conductivity environment such as marly-clays.
Hua Rongrong - One of the best experts on this subject based on the ideXlab platform.
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analysis on application of ground source heat pump system in Retrofit Project
Building Science, 2007Co-Authors: Hua RongrongAbstract:In this paper,based on the analysis of the advantages and disadvantages of ground source heat pump system,the Retrofit program of cold and heat sources for a sanatorium in Dalian was discussed.Through the on-the-spot investigation and calculation,the traditional air-conditioning and heating systems of existing buildings could be transformed into ground source heat pump systems.Although the initial investment would be higher than others,energy resource could be greatly saved and the operating cost of air-conditioning system could be reduced.
Xiaohua Xia - One of the best experts on this subject based on the ideXlab platform.
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Maintenance optimization incorporating lumen degradation failure for energy-efficient lighting Retrofit Projects
Applied Energy, 2020Co-Authors: Alice Ikuzwe, Xiaohua XiaAbstract:Abstract This study presents an optimal lighting maintenance plan that takes into account lumen degradation failure. In lighting Retrofit Projects, Retrofitted lights fail over time mainly owing to burnout and lumen degradation failures. These failures result in a reduced illumination level and lower Project savings if proper maintenance is not performed. Previous studies developed lighting maintenance plans by modeling lamp population decay due to burnout failure. In this study, we present an optimal lighting maintenance plan based on lumen degradation failure. The lumen degradation failure is modeled based on the statistical properties of degradation rates. By using the Kaplan–Meier method, the formulated lumen degradation failure is used to model the surviving population. The surviving population model is used to design an optimal lighting maintenance plan, which maximizes energy savings and minimizes maintenance costs. The effectiveness of the formulated maintenance plan is demonstrated by an actual residential energy-efficient lighting Retrofit Project implemented in South Africa. Results show that the proposed maintenance plan is more cost-effective than full maintenance.
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Energy optimisations in large-scale lighting Retrofit Projects
2017 36th Chinese Control Conference (CCC), 2017Co-Authors: Xiaohua XiaAbstract:Energy optimisation techniques can be suitably applied to support energy efficiency lighting Retrofits in buildings. In previous studies, optimal measurement and verification (M&V) plans are developed to quantify energy savings realised by implementing large-scale lighting Retrofit Projects. In addition, optimal maintenance plans for the implemented energy efficiency lighting systems are also identified to maximise the Project profits and energy savings. All these efforts aim to control the investment cost for large-scale lighting Retrofit Projects while producing more benefits for Project participants in terms of financial benefits and energy savings. In order to further improve the cost-effectiveness of lighting Retrofit activities, an optimal implementation plan (OIP) is designed in this study, which is obtained by solving an optimisation problem whose objective function is to maximise the cost-benefit ratio subject to the constraints of planned Project scope and budget availability of a large-scale lighting Retrofit Project. When applying the OIP to a practical lighting Retrofit Project in a case study, it shows that the OIP is able to increase the Project cost-benefit ratio by 33% with a significant reduction of the initial investment by 62% compared to the state-of-art research results, which clearly illustrates the effectiveness of the proposed energy optimisation model.
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optimal maintenance planning for sustainable energy efficiency lighting Retrofit Projects by a control system approach
Control Engineering Practice, 2015Co-Authors: Xiaohua Xia, Lijun Zhang, Bing ZhuAbstract:Abstract The energy savings achieved by implementing energy efficiency (EE) lighting Retrofit Projects are sometimes not sustainable and vanish rapidly given that lamp population decays as time goes by if without proper maintenance activities. Scope of maintenance activities refers to replacements of failed lamps due to nonrepairable lamp burnouts. Full replacements of all the failed lamps during each maintenance interval contribute to a tight Project budget due to the expense for the lamp failure inspections, as well as the procurement and installation of new lamps. Since neither “no maintenance” nor “full maintenance” is preferable to the EE lighting Project developers (PDs), we propose to design an optimal maintenance plan that optimises the number of replacements of the failed lamps, such that the EE lighting Project achieves sustainable performance in terms of energy savings whereas the PDs obtain their maximum benefits in the sense of cost–benefit ratio. This optimal maintenance planning (OMP) problem is aptly formulated as an optimal control problem under control system framework, and solved by a model predictive control (MPC) approach. An optimal maintenance plan for an EE lighting Retrofit Project is designed as a case study to illustrate the effectiveness of the proposed control system approach.
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Optimal Sampling and Maintenance Plans for the Lighting Retrofit Projects Towards Sustainable Energy Savings
Energy Procedia, 2014Co-Authors: Xiaohua XiaAbstract:Abstract In this article, the optimal sampling and maintenance plans are both designed for the EE lighting Retrofit Projects. By adopting the optimal solutions, the Project sponsors receive additional and sustainable energy savings over a 10-years’ crediting period. The reported Project performance is accurate enough to satisfy the Project sampling accuracy requirements. In addition, the PDs’ profit is maximised with a proper reinvestment for the lighting Project maintenance. A case study of designing the optimal sampling and maintenance plans for an EE lighting Retrofit Project is presented for illustrative purpose.