The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
Lieve Helsen - One of the best experts on this subject based on the ideXlab platform.
-
Short-term modeling of hybrid geothermal systems for Model Predictive Control
Energy and Buildings, 2020Co-Authors: Iago Cupeiro Figueroa, Damien Picard, Lieve HelsenAbstract:Abstract Model Predictive Control (MPC) has shown significant energy savings potential in the operation of building energy systems, yet it needs accurate and simple models for optimization. In hybrid geothermal systems the source-side temperatures affect the system efficiency and its operational feasibility. Since the ground dynamics are rather slow, simplifications such as considering a constant coefficient of performance (COP) are made. We evaluate the added value of including a short-term dynamic borefield model to the controller. Simulations are performed in a heating-dominated building equipped with a hybrid geothermal system for two winter weeks. We consider 4 different modeling strategies where the formulation of the COP and the Return Fluid temperature from the borefield is varied in complexity. Results show that using a constant COP results in a bang-bang behavior of the heat pump, while with an accurate prediction of the COP the operation is smoother, saving 0.46%, 1.86% and 2.71% for low, average and high electricity-to-gas price ratios respectively. Including a short-term borefield model avoids shutting down the heat pump due to safety constraints which saves up to 8.12% more money while the use of the ground-source is quintupled. Despite reducing the optimization iteration number by almost 18%, simulation time is increased.
Iago Cupeiro Figueroa - One of the best experts on this subject based on the ideXlab platform.
-
Short-term modeling of hybrid geothermal systems for Model Predictive Control
Energy and Buildings, 2020Co-Authors: Iago Cupeiro Figueroa, Damien Picard, Lieve HelsenAbstract:Abstract Model Predictive Control (MPC) has shown significant energy savings potential in the operation of building energy systems, yet it needs accurate and simple models for optimization. In hybrid geothermal systems the source-side temperatures affect the system efficiency and its operational feasibility. Since the ground dynamics are rather slow, simplifications such as considering a constant coefficient of performance (COP) are made. We evaluate the added value of including a short-term dynamic borefield model to the controller. Simulations are performed in a heating-dominated building equipped with a hybrid geothermal system for two winter weeks. We consider 4 different modeling strategies where the formulation of the COP and the Return Fluid temperature from the borefield is varied in complexity. Results show that using a constant COP results in a bang-bang behavior of the heat pump, while with an accurate prediction of the COP the operation is smoother, saving 0.46%, 1.86% and 2.71% for low, average and high electricity-to-gas price ratios respectively. Including a short-term borefield model avoids shutting down the heat pump due to safety constraints which saves up to 8.12% more money while the use of the ground-source is quintupled. Despite reducing the optimization iteration number by almost 18%, simulation time is increased.
Roshan Sharma - One of the best experts on this subject based on the ideXlab platform.
-
Estimation of Mud Losses during the Removal of Drill Cuttings in Oil Drilling
SPE Journal, 2020Co-Authors: Asanthi Jinasena, Roshan SharmaAbstract:Summary Quantification of Fluid losses at the topside is beneficial for early kick-loss detection and automation of the drilling operation. A model-based estimator is a useful tool for this purpose. The real-time estimation of the amount of Fluid losses with the cuttings removal could significantly help in this regard, especially for kick detection and automation. However, to the authors’ knowledge, there is no published literature on such attempts. Therefore, a simple dynamic mathematical model of the complete closed-loop oil-well drilling system is developed in this study for estimation of the Fluid losses during the removal of drill cuttings at the topside, as well as for monitoring the flow of Return Fluid during drilling. Furthermore, this model could provide information about the topside Fluid-flow rates and Fluid losses to other monitoring systems, such as kick- and loss-detection systems and automation systems. The model is used to estimate both the mud-pit level and the Fluid losses during the removal of the drill cuttings through the solids-removal equipment. The model-order reduction of the flowline model using orthogonal collocation allows the model to be used in real-time estimations and/or with control systems. It is simple, easy to implement, and, more importantly, shows the necessary dynamic behavior of both the bottomside and topside of a drilling operation simultaneously. The topside model can be used together with bottomside models of varying complexity to estimate both the bottomhole pressure and the Fluid losses through the solids-removal system.
-
A dynamic model for drain back to active mud pit combined with a well model during drilling
Journal of Petroleum Science and Engineering, 2018Co-Authors: Ivan Pirir, Asanthi Jinasena, Roshan SharmaAbstract:Abstract There are no published mathematical models that combine the dynamics of the Returned Fluid flow to the active mud pit (top side drilling) and the dynamics of the bottom side of the well being drilled. In this paper a simple dynamic model that combines the top and the bottom side drilling operations is provided. The model has been simulated for various operational scenarios during drilling including pipe connection, movements of drill string and reservoir influx. This combined model can be used for studying not only the pressure dynamics but also to estimate the Return Fluid flow rate and hence to detect kicks and losses occurring in the well.
-
Model based flow measurement using venturi flumes for Return flow during drilling
Norwegian Society of Automatic Control, 2017Co-Authors: Ivan Pirir, Asanthi Jinasena, Roshan SharmaAbstract:In an oil well drilling operation, a proper knowledge of the Return Fluid flowrate is necessary both for the stabilization of the bottom hole pressure of the well and also as a primary indication of a kick or loss. In practice, the drill Fluid flowing through the Return line is usually measured with Coriolis meters. However this method is both expensive and has some downsides. For instance there is a risk of blockage due to drill cuttings while measuring the discharge. The presence of gas and cuttings in the drilling Fluid will also have a negative effect in the measurement i.e. for multi-phase Fluid, the readings from Coriolis meters may not be accurate. A cheaper alternative would be to use an open channel for the measurement of the discharge from the Return flowline. In this paper, a venturi rig is used as the open channel and modeled by the Saint Venant equations. Experimental verification of the simulation results show a promising behavior of the model based measurement of the Return Fluid flow
-
Model based flow measurement using venturi umes for Return flow during drilling
Modeling Identification and Control: A Norwegian Research Bulletin, 2017Co-Authors: Ivan Pirir, Asanthi Jinasena, Roshan SharmaAbstract:In an oil well drilling operation, a proper knowledge of the Return Fluid flowrate is necessary both for the stabilization of the bottom hole pressure of the well and also as a primary indication of a kick or loss. In practice, the drill Fluid flowing through the Return line is usually measured with Coriolis meters. However this method is both expensive and has some downsides. For instance there is a risk of blockage due to drill cuttings while measuring the discharge. The presence of gas and cuttings in the drilling Fluid will also have a negative effect in the measurement i.e. for multi-phase Fluid, the readings from Coriolis meters may not be accurate. A cheaper alternative would be to use an open channel for the measurement of the discharge from the Return flowline. In this paper, a venturi rig is used as the open channel and modeled by the Saint Venant equations. Experimental verification of the simulation results show a promising behavior of the model based measurement of the Return Fluid flow
Damien Picard - One of the best experts on this subject based on the ideXlab platform.
-
Short-term modeling of hybrid geothermal systems for Model Predictive Control
Energy and Buildings, 2020Co-Authors: Iago Cupeiro Figueroa, Damien Picard, Lieve HelsenAbstract:Abstract Model Predictive Control (MPC) has shown significant energy savings potential in the operation of building energy systems, yet it needs accurate and simple models for optimization. In hybrid geothermal systems the source-side temperatures affect the system efficiency and its operational feasibility. Since the ground dynamics are rather slow, simplifications such as considering a constant coefficient of performance (COP) are made. We evaluate the added value of including a short-term dynamic borefield model to the controller. Simulations are performed in a heating-dominated building equipped with a hybrid geothermal system for two winter weeks. We consider 4 different modeling strategies where the formulation of the COP and the Return Fluid temperature from the borefield is varied in complexity. Results show that using a constant COP results in a bang-bang behavior of the heat pump, while with an accurate prediction of the COP the operation is smoother, saving 0.46%, 1.86% and 2.71% for low, average and high electricity-to-gas price ratios respectively. Including a short-term borefield model avoids shutting down the heat pump due to safety constraints which saves up to 8.12% more money while the use of the ground-source is quintupled. Despite reducing the optimization iteration number by almost 18%, simulation time is increased.
Robert Weinstein - One of the best experts on this subject based on the ideXlab platform.
-
Pentastarch as partial replacement Fluid for therapeutic plasma exchange: Effect on plasma proteins, adverse events during treatment, and serum ionized calcium
Journal of clinical apheresis, 1999Co-Authors: Geraldine A. Goss, Robert WeinsteinAbstract:We compared the safety, effect on plasma proteins, and contribution to hypocalcemic toxicity of 10% pentastarch vs. 5% albumin in plasma exchange. Thirty-two neurology patients underwent 161 plasma exchange procedures. Subjects were randomized to receive either 10% pentastarch (n = 17) or 5% albumin (n = 15) as the first (1/2) of colloid replacement. The second (1/2) of colloid replacement was 5% albumin in all cases. NaCl (plus small amounts of ACD-A) accounted for (1/4) of the total Return Fluid. Mean total exchange volume was 3,842.6 +/- 450 ml. Hemoglobin, platelet count, coagulation parameters, and plasma fibrinogen were similar between the two groups at the outset of plasma exchange and at the time of the last (4th or 5th) procedure of the series. Immunoglobulin levels were equivalent at the outset and were reduced by plasma exchange to the same extent in the two groups. Serum albumin concentration fell significantly faster in the group receiving pentastarch. On the other hand, serum calcium, corrected for the albumin concentration, fell significantly further in the control group than in the group receiving pentastarch. Mean serum ionized calcium fell approximately 25 % in procedures using only albumin but only approximately 16% when pentastarch was used (P < 0.0001). This was reflected in the occurrence of hypocalcemic toxicity in 33.3% of procedures performed using only albumin but in only 8.1% of those using pentastarch (P = 0.0002). Pentastarch may be suitable for partial colloid replacement in plasma exchange and would have saved our hospital $127,050 to $434,280 in 1998 if used in all procedures.
-
prevention of citrate reactions during therapeutic plasma exchange by constant infusion of calcium gluconate with the Return Fluid
Journal of Clinical Apheresis, 1996Co-Authors: Robert WeinsteinAbstract:We have examined the effectiveness of intravenous calcium gluconate infusion in the prevention of citrate reactions during therapeutic plasma exchange. Over 2 years, 636 procedures were performed on 90 patients, mostly for treatment of neurological disorders. Return Fluid consisted of 4–5% human serum albumin in 0.9% NaCl. Anticoagulant ACD-A was used at a starting ratio of 1:16. Whole blood flow rates were 70–80% ml/min. Treatments were divided into three groups for management of citrate reactions: Group A (360 treatments) were managed using simple measures only, including slowing the whole blood flow rate, altering the ACD:whole blood flow ratio, and oral calcium carbonate wafers; Group B (102 treatments) received small intravenous boluses of 10% calcium gluconate, up to 25 ml during the procedure; Group C (174 treatments) received constant infusion of calcium gluconate (10 ml/liter of Return Fluid) during the procedure. Citrate reactions occurred in 35.6% of Group A and 29.4% of Group B treatments (P = 0.3), but in only 8.6% of Group C treatments (P < 0.0001). Men with and without reactions were the same age (mean 63.3 vs. 61 years, P = 0.0823), but women with reactions were younger than women without reactions (mean 49.9 vs 57.9 years, P < 0.0001). Supplementation of the Return Fluid with calcium gluconate is an effective, convenient, and well-tolerated method for prevention of citrate toxicity during therapeutic plasma exchange procedures using albumin-based Return Fluid. © 1996 Wiley-Liss, Inc.
-
prevention of citrate reactions during therapeutic plasma exchange by constant infusion of calcium gluconate with the Return Fluid
Journal of Clinical Apheresis, 1996Co-Authors: Robert WeinsteinAbstract:We have examined the effectiveness of intravenous calcium gluconate infusion in the prevention of citrate reactions during therapeutic plasma exchange. Over 3 years, 636 procedures were performed on 90 patients, mostly for treatment of neurological disorders. Return Fluid consisted of 4-5% human serum albumin in 0.9% NaCl. Anticoagulant ACD-A was used at a starting ratio of 1:16. Whole blood flow rates were 70-80 ml/min. Treatments were divided into three groups for management of citrate reactions: Group A (360 treatments) were managed using simple measures only, including slowing the whole blood flow rate, altering the ACD:whole blood flow ratio, and oral calcium carbonate wafers; Group B (102 treatments) received small intravenous boluses of 10% calcium gluconate, us to 25 ml during the procedure; Group C (174 treatments) received constant infusion of calcium gluconate (10 ml/liter of Return Fluid) during the procedure. Citrate reactions occurred in 35.6% of Group A and 29.4% of Group B treatments (P = 0.3), but in only 8.6% of Group C treatments (P < 0.0001). Men with and without reactions were the same age (mean 63.3 vs. 61 years, P = 0.0823), but women with reactions were younger than women without reactions (mean 49.9 vs. 57.9 years, P < 0.0001). Supplementation of the Return Fluid with calcium gluconate is an effective, convenient, and well-tolerated method for prevention of citrate toxicity during therapeutic plasma exchange procedures using albumin-based Return Fluid.