The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Angelo Zarrella - One of the best experts on this subject based on the ideXlab platform.
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investigations on the influence of aquifers on the Ground Temperature in Ground source heat pump operation
Applied Energy, 2013Co-Authors: Antonio Capozza, Michele De Carli, Angelo ZarrellaAbstract:The winter operation of Ground-source heat pumps is expected to lead to Temperature decrease in the zones surrounding the vertical Ground heat exchangers. The following thermal drift phenomenon occurring over the years is still deeply studied from both the experimental and the theoretical viewpoint.
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investigations on the influence of aquifers on the Ground Temperature in Ground source heat pump operation
Applied Energy, 2013Co-Authors: Antonio Capozza, Michele De Carli, Angelo ZarrellaAbstract:Abstract The winter operation of Ground-source heat pumps is expected to lead to Temperature decrease in the zones surrounding the vertical Ground heat exchangers. The following thermal drift phenomenon occurring over the years is still deeply studied from both the experimental and the theoretical viewpoint. A moving aquifer tends to oppose the thermal drift, due to the advection Groundwater phenomena. For this purpose, a modelling study on the quantitative influence of the Groundwater flow on the thermal drift is performed. Then, the analytical solution of the moving infinite line source is applied. Different forms (closed analytical, asymptotical or tabled one) are identified for this solution depending on the value range of the thermal physical parameters of the system. Referring to a particularly critical case study, an easy-to-use application of the model based on this analytical solution is then presented. An evaluation is carried out as well on the interaction between the existing borefield and a nearby one, being operated afterwards, in presence of either still or moving aquifer. Finally, the influence of the actually existing flow upon improving the effective operating conditions of the heat pump plant is assessed. Moreover, when Groundwater flow is taken into account, the decrease of the total borehole length is evaluated.
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a computational capacity resistance model carm for vertical Ground coupled heat exchangers
Renewable Energy, 2010Co-Authors: Michele De Carli, Angelo Zarrella, Massimo Tonon, Roberto ZecchinAbstract:Several models are available in literature to simulate Ground heat exchangers. In this paper an approach based on electrical analogy is presented, for this reason named CaRM (CApacity Resistance Model). In some cases several information are needed during design: both the borehole and the surrounding Ground are affected by thermal exchange. The model here presented allows to consider the fluid flow pattern along the classical vertical Ground heat exchangers as a single U-tube, a double U-tube or coaxial pipes. Besides, Ground Temperature at different distances from borehole are calculated, taking into account also the thermal interference between more boreholes. Starting from the supply Temperature to the heat exchanger, the outlet fluid Temperature is calculated and the Ground Temperature in each node, step by step. The model has been validated by means of a commercial software based on the finite differences method. Further comparisons have been carried out against data from a Ground thermal response test and from the survey of an office building equipped with a Ground coupled heat pump and vertical double U-tube heat exchangers. The agreement of results validates the model here presented.
Zine Aidoun - One of the best experts on this subject based on the ideXlab platform.
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a new modeling approach for improved Ground Temperature profile determination
Renewable Energy, 2016Co-Authors: Messaoud Badache, Mohamed Ouzzane, Parham Eslaminejad, Zine Aidoun, Louis LamarcheAbstract:Abstract The knowledge of the Ground Temperature profile with respect to time and depth is very important in many technological fields like geothermal heat pumps, solar energy systems and geotechnical applications. Many researches were performed in the past in order to evaluate this profile. The most common ones, known as energy balance models, use the energy balance equation as a boundary condition. Unfortunately the performance of these models strongly depends on an accurate estimation of several input factors. The objective of this paper is to develop an improved model for the prediction of the Ground Temperature profile in which the energy balance equation at the Ground surface is supplemented by an empirical correlation for the annual average Ground surface Temperature calculation. This model is less sensitive to uncertainties of input factors. Furthermore, unlike the previous models, a periodic variation of the sky Temperature is introduced instead of a previously assumed constant value. The model is validated against measured data in a site located in Varennes (Montreal-Canada) and two further sites, Fort Collins (Colorado) and Temple (Texas) in the U.S.A.
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new correlations for the prediction of the undisturbed Ground Temperature
Geothermics, 2015Co-Authors: Mohamed Ouzzane, Parham Eslaminejad, Messaoud Badache, Zine AidounAbstract:Abstract The undisturbed Ground Temperature is an important parameter in the design of the Ground heat exchanger connected to the Ground source heat pump systems. Based on the heating mode for cold climates, the underestimation of this parameter leads to oversizing the Ground heat exchanger length and therefore resulting in the additional cost of the system. Using measured data obtained from thermal response test (TRT) reports for seventeen sites covering a wide range of climates, two different correlations of the undisturbed Ground Temperature, global and simplified have been developed. The first one, obtained using the least square method, is a function of ambient air Temperature, wind velocity, global solar radiation on a horizontal surface and sky Temperature. It has been shown by using this correlation that the air ambient Temperature is the dominant parameter on the undisturbed Ground Temperature. Following this conclusion, the simplified correlation which is only a function of the air ambient Temperature was developed. Then using this latter correlation, isotherms of the undisturbed Ground Temperature for Canada were generated.
Michele De Carli - One of the best experts on this subject based on the ideXlab platform.
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investigations on the influence of aquifers on the Ground Temperature in Ground source heat pump operation
Applied Energy, 2013Co-Authors: Antonio Capozza, Michele De Carli, Angelo ZarrellaAbstract:The winter operation of Ground-source heat pumps is expected to lead to Temperature decrease in the zones surrounding the vertical Ground heat exchangers. The following thermal drift phenomenon occurring over the years is still deeply studied from both the experimental and the theoretical viewpoint.
-
investigations on the influence of aquifers on the Ground Temperature in Ground source heat pump operation
Applied Energy, 2013Co-Authors: Antonio Capozza, Michele De Carli, Angelo ZarrellaAbstract:Abstract The winter operation of Ground-source heat pumps is expected to lead to Temperature decrease in the zones surrounding the vertical Ground heat exchangers. The following thermal drift phenomenon occurring over the years is still deeply studied from both the experimental and the theoretical viewpoint. A moving aquifer tends to oppose the thermal drift, due to the advection Groundwater phenomena. For this purpose, a modelling study on the quantitative influence of the Groundwater flow on the thermal drift is performed. Then, the analytical solution of the moving infinite line source is applied. Different forms (closed analytical, asymptotical or tabled one) are identified for this solution depending on the value range of the thermal physical parameters of the system. Referring to a particularly critical case study, an easy-to-use application of the model based on this analytical solution is then presented. An evaluation is carried out as well on the interaction between the existing borefield and a nearby one, being operated afterwards, in presence of either still or moving aquifer. Finally, the influence of the actually existing flow upon improving the effective operating conditions of the heat pump plant is assessed. Moreover, when Groundwater flow is taken into account, the decrease of the total borehole length is evaluated.
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a computational capacity resistance model carm for vertical Ground coupled heat exchangers
Renewable Energy, 2010Co-Authors: Michele De Carli, Angelo Zarrella, Massimo Tonon, Roberto ZecchinAbstract:Several models are available in literature to simulate Ground heat exchangers. In this paper an approach based on electrical analogy is presented, for this reason named CaRM (CApacity Resistance Model). In some cases several information are needed during design: both the borehole and the surrounding Ground are affected by thermal exchange. The model here presented allows to consider the fluid flow pattern along the classical vertical Ground heat exchangers as a single U-tube, a double U-tube or coaxial pipes. Besides, Ground Temperature at different distances from borehole are calculated, taking into account also the thermal interference between more boreholes. Starting from the supply Temperature to the heat exchanger, the outlet fluid Temperature is calculated and the Ground Temperature in each node, step by step. The model has been validated by means of a commercial software based on the finite differences method. Further comparisons have been carried out against data from a Ground thermal response test and from the survey of an office building equipped with a Ground coupled heat pump and vertical double U-tube heat exchangers. The agreement of results validates the model here presented.
Mohamed Ouzzane - One of the best experts on this subject based on the ideXlab platform.
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a new modeling approach for improved Ground Temperature profile determination
Renewable Energy, 2016Co-Authors: Messaoud Badache, Mohamed Ouzzane, Parham Eslaminejad, Zine Aidoun, Louis LamarcheAbstract:Abstract The knowledge of the Ground Temperature profile with respect to time and depth is very important in many technological fields like geothermal heat pumps, solar energy systems and geotechnical applications. Many researches were performed in the past in order to evaluate this profile. The most common ones, known as energy balance models, use the energy balance equation as a boundary condition. Unfortunately the performance of these models strongly depends on an accurate estimation of several input factors. The objective of this paper is to develop an improved model for the prediction of the Ground Temperature profile in which the energy balance equation at the Ground surface is supplemented by an empirical correlation for the annual average Ground surface Temperature calculation. This model is less sensitive to uncertainties of input factors. Furthermore, unlike the previous models, a periodic variation of the sky Temperature is introduced instead of a previously assumed constant value. The model is validated against measured data in a site located in Varennes (Montreal-Canada) and two further sites, Fort Collins (Colorado) and Temple (Texas) in the U.S.A.
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new correlations for the prediction of the undisturbed Ground Temperature
Geothermics, 2015Co-Authors: Mohamed Ouzzane, Parham Eslaminejad, Messaoud Badache, Zine AidounAbstract:Abstract The undisturbed Ground Temperature is an important parameter in the design of the Ground heat exchanger connected to the Ground source heat pump systems. Based on the heating mode for cold climates, the underestimation of this parameter leads to oversizing the Ground heat exchanger length and therefore resulting in the additional cost of the system. Using measured data obtained from thermal response test (TRT) reports for seventeen sites covering a wide range of climates, two different correlations of the undisturbed Ground Temperature, global and simplified have been developed. The first one, obtained using the least square method, is a function of ambient air Temperature, wind velocity, global solar radiation on a horizontal surface and sky Temperature. It has been shown by using this correlation that the air ambient Temperature is the dominant parameter on the undisturbed Ground Temperature. Following this conclusion, the simplified correlation which is only a function of the air ambient Temperature was developed. Then using this latter correlation, isotherms of the undisturbed Ground Temperature for Canada were generated.
Ryozo Ooka - One of the best experts on this subject based on the ideXlab platform.
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development of chiller attached apparatus for accurate initial Ground Temperature measurement insights from global sensitivity analysis of thermal response tests
Energy and Buildings, 2021Co-Authors: Wonjun Choi, Ruchi Choudhary, Ryozo OokaAbstract:Abstract Local sensitivity analysis (LSA) is widely used for evaluating the uncertainty in a model output or estimated parameters. However, it does not consider the effect of changing parameter values in the parameter space and the simultaneous change of the parameter set. Global sensitivity analysis (GSA) overcomes these limitations of LSA by adequately representing the propagated uncertainty in model usage or parameter estimation. In this study, by using Sobol’s method, GSA was conducted to analyze the temporal uncertainty transition of model inputs required in the thermal property estimation via a Ground thermal response test (TRT). The obtained results provide important insights; specifically, among the various input parameters, the initial Ground Temperature and Ground volumetric heat capacity account for more than ∼27% and ∼20% of the total uncertainty in borehole resistance estimation, respectively. Further, the estimated borehole resistance is larger than intended owing to the uncertainty in the borehole diameter, which is likely to increase during the construction process. Thus, a deterministic estimation by fixing the borehole diameter leads to a lower estimate than the actual resistance. Then, the insights obtained are used to develop a chiller-attached TRT apparatus to solve the limitations of conventional apparatuses that cannot measure the initial Ground Temperature accurately. By using the developed apparatus that can accurately control the fluid Temperature, the Temperature at which the circulating fluid and surrounding soil are in thermal equilibrium can be asymptotically found with an uncertainty range of 0.1 °C. This improvement in the initial Temperature accuracy results in a 24% reduction in the estimation uncertainty of the borehole resistance compared to conventional practice.
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optimization method for multiple heat source operation including Ground source heat pump considering dynamic variation in Ground Temperature
Applied Energy, 2017Co-Authors: Shintaro Ikeda, Wonjun Choi, Ryozo OokaAbstract:Recent years have witnessed the widespread use of highly efficient energy systems as an important measure to reduce not only energy consumption but also operating costs. A Ground source heat pump system has been attracting considerable attention because of its high efficiency. Although many studies have been conducted to investigate and evaluate the Ground source heat pump’s performance, they have not sufficiently studied its optimal operation considering dynamic Ground Temperature variation caused by the high thermal capacity of the Ground. Calculations considering both thermal history of the Ground and optimal load dispatch are complicated and thus entail high computation costs. In this paper, an efficient optimization method is proposed to determine optimal operations of a hybrid Ground source heat pump system that is used to handle the cooling load and hot water demand. The proposed method, namely epsilon-constrained differential evolution with random jumping, can solve nearly all possible configurations and is a suitable method for the nonlinear configuration used herein because the Ground source heat pump has highly nonlinear characteristics and the Ground Temperature calculation cannot be simplified to a linear formulation. The optimal operations achieved by the proposed method can reduce operating costs by at least 3.78% and at most 12.56% compared to empirical operations. In addition, the proposed method derives the solution rapidly while maintaining high computation accuracy. Therefore, it can be used in practical situations to determine an optimal operating schedule as a day-ahead optimization.
