Time filter

Source Type

Chaturvedi S.K.,Old Dominion University | Gagrani V.D.,DNV KEMA Energy and Sustainability | Abdel-Salam T.M.,East Carolina University
Energy Conversion and Management | Year: 2014

Direct expansion solar assisted heat pump systems (DX-SAHP) have been widely used in many applications including water heating. In the DX-SAHP systems the solar collector and the heat pump evaporator are integrated into a single unit in order to transfer the solar energy to the refrigerant. The present work is aimed at studying the use of the DX-SAHP for low temperature water heating applications. The novel aspect of this paper involves a detailed long-term thermo-economic analysis of the energy conservation potential and economic viability of these systems. The thermal performance is simulated using a computer program that incorporates location dependent radiation, collector, economic, heat pump and load data. The economic analysis is performed using the life cycle cost (LCC) method. Results indicate that the DX-SAHP water heaters systems when compared to the conventional electrical water heaters are both economical as well as energy conserving. The analysis also reveals that the minimum value of the system life cycle cost is achieved at optimal values of the solar collector area as well as the compressor displacement capacity. Since the cost of SAHP system presents a barrier to mass scale commercialization, the results of the present study indicating that the SAHP life cycle cost can be minimized by optimizing the collector area would certainly be helpful in lowering, if not eliminating, the economic barrier to these systems. Also, at load temperatures higher than 70 C, the performance of the single stage heat pump degrades to the extent that its cost and efficiency advantages over the electric only system are lost. © 2013 Elsevier Ltd. All rights reserved.

Gersen S.,DNV KEMA Energy and Sustainability | Darmeveil H.,DNV KEMA Energy and Sustainability | Levinsky H.,DNV KEMA Energy and Sustainability | Levinsky H.,University of Groningen
Combustion and Flame | Year: 2012

Autoignition delay times of stoichiometric and fuel-lean (=0.5) H 2, H 2/CO, CH 4, CH 4/CO, CH 4/H 2 and CH 4/CO/H 2 mixtures have been measured in an Rapid Compression Machine at pressures ranging from 20 to 80bar and in the temperature range 900-1100K. The effects of CO addition on the ignition of H 2, to 50% CO in the fuel, and CH 4, to 20% CO in the fuel, are observed to be negligible both experimentally and computationally for the conditions studied here. The addition of syngas to methane results in ignition behavior that resembles an equivalent methane/hydrogen fuel mixture with the same hydrogen fraction. In contrast to results previous presented in the literature, we thus observe no inhibiting effect from CO for the conditions in our experiments. © 2012 The Combustion Institute.

Hermeling C.,Center for European Economic Research | Loschel A.,Center for European Economic Research | Loschel A.,University of Heidelberg | Mennel T.,DNV KEMA Energy and Sustainability
Energy Policy | Year: 2013

This paper introduces a new method for stochastic sensitivity analysis for computable general equilibrium (CGE) model based on Gauss Quadrature and applies it to check the robustness of a large-scale climate policy evaluation. The revised version of the Gauss-quadrature approach to sensitivity analysis reduces computations considerably vis-à-vis the commonly applied Monte-Carlo methods; this allows for a stochastic sensitivity analysis also for large scale models and multi-dimensional changes of parameters. In the application, an impact assessment of EU2020 climate policy, we focus on sectoral elasticities that are part of the basic parameters of the model and have been recently determined by econometric estimation, alongside with standard errors. The impact assessment is based on the large scale CGE model PACE. We show the applicability of the Gauss-quadrature approach and confirm the robustness of the impact assessment with the PACE model. The variance of the central model outcomes is smaller than their mean by order four to eight, depending on the aggregation level (i.e. aggregate variables such as GDP show a smaller variance than sectoral output). © 2012.

Polman H.,DNV KEMA Energy and Sustainability | Verhaart F.,Deltares | Bruijs M.,DNV KEMA Energy and Sustainability
Desalination and Water Treatment | Year: 2013

Colonization of cooling water systems (CWS) by fouling organisms is a major concern for industries, power, and desalination plants over the world. Biofouling results in, depending on the dimensions of the biofouling species and growth patterns, an increased wall roughness and reduction of the inner pipe diameter. This leads to a significant head loss in the intake structure. To prevent settlement and growth of fouling species, an effective antifouling treatment is required. However, fouling mitigation must be applied from early start of operation of an installation, as several species cannot be fully mitigated (chemically) or removed (physically) after settlement, as some of them (e.g. barnacles, the Japanese oyster and Rock oyster) cement themselves to the surface. This means that even after a physical cleaning, part of the organisms remains on the surface, resulting in an irreversible increased head loss and a decreased pump capacity. To provide some clearance on the impact of biofouling on pump capacity in CWS, two cases have been studied. The results show that nonoptimal fouling treatments result in significant additional annual energy consumption. Even after complete physical cleaning, the remaining head loss is above the design line due to the increased wall roughness and results in decreased pump capacity. The results strongly emphasize the necessity to apply an effective biofouling control during the start-up of a water intake system prior to commercial operation, or to have system design parameters which take into account the irreversible effects of biofouling. © 2013 Desalination Publications.

Behnke M.,DNV KEMA Energy and Sustainability | Ellis A.,Sandia National Laboratories
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2013

As an important part of evaluating the transmission and distribution system impacts of interconnecting new generation sources, network operators must assess the impact of these sources on fault interrupting capabilities of automatic switching devices and protective relay coordination for balanced and unbalanced faults on the network. A growing component of these new generation sources is solar photovoltaic-based systems. Modeling of these sources for short circuit studies is complicated by the non-linear control characteristics of their associated inverters. These characteristics preclude the use of linear circuit analysis techniques based on Thévenin equivalents that are the prevalent methodologies relied upon in most commercial short circuit analysis tools. This paper contrasts the physical characteristics of well-understood synchronous generator technology with that of modern-day PV inverter technology. Limitations of commercial short circuit analysis tools for addressing solar PV generation systems, and recommendations for development of industry consensus standard analysis methods, are presented. © 2013 IEEE.

Sloterdijk W.,DNV KEMA Energy and Sustainability | Hommes M.,DNV KEMA Energy and Sustainability
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2012

In today's challenging environment, the priority for many oil and gas operation companies is to design, build and safely operate facilities at optimum cost efficiency. This means that new facility designs must consider critical facility integrity and that existing facilities are operated well beyond their intended design life. Main gas transmission systems are now some 50 years old and operate for longer periods than anticipated during design and construction for reasons such as; the transition to renewables with another 50 years of service foreseen, and; gas transmission systems that operate satisfactorily, have very low failure rates and for which the planned safe life time extension is expected to be the lowest cost option. Thus, questions are raised how existing gas transmission systems can safely contribute to the total energy system in coming decades. Where a lot of developments are toward integrity assurance of pipelines (ASME B31.8S [1], ILI etc.), facilities receive less attention even though they are an integral and essential part of the system. In this paper a systematic approach for assessing integrity of new and existing facilities that leads to a structured inspection and test plan is developed and presented. This system based approach is introduced and explained and applied to two recent case studies. Copyright © 2012 by ASME.

Stam A.F.,DNV KEMA Energy and Sustainability
Advances in Materials Technology for Fossil Power Plants - Proceedings from the 7th International Conference | Year: 2014

The EU NextGenPower-project aims at demonstrating Ni-alloys and coatings for application in high-efficiency power plants. Fireside corrosion lab and plants trials show that A263 and A617 perform similar while A740H outperforms them. Lab tests showed promising results for NiCr, Diamalloy3006 and SHS9172 coatings. Probe trials in six plants are ongoing. A617, A740H and A263 performed equally in steamside oxidation lab test ≤750°C while A617 and A740H outperformed A263 at 800°C; high pressure tests are planned. Slow strain rate testing confirmed relaxation cracking of A263. A creep-fatigue interaction test program for A263 includes LCF tests. Negative creep of A263 is researched with gleeble tests. A263 Ø80 - 500mm trial rotors are forged with optimized composition. Studies for designing and optimizing the forging process were done. Segregation free Ø300 and 1,000mm rotors have been forged. A263 - A263 and A293 - COST F rotor welding show promising results (A263 in precipitation hardened condition). Cast step blocks of A282, A263 and A740H showed volumetric cracking after heat treatment. New 'as cast' blocks of optimized composition are without cracks. A 750°C steam cycle has been designed with integrated C02 capture at 45% efficiency (LHV). Superheater life at ≤750°C and co-firing is modeled. Copyright © 2014 Electric Power Research Institute, Inc. Distributed by ASM International®. All rights reserved.

Solomon S.,DNV KEMA Energy and Sustainability | Flach T.,DNV KEMA Energy and Sustainability
Sustainable Earth Sciences, SES 2013: Technologies for Sustainable Use of the Deep Sub-Surface | Year: 2013

Use of the subsurface has become steadily more intensive and globalized. This is due to wider application of conventional uses and to the emergence of relatively new, unconventional uses. This raises the question of whether we are managing the subsurface space in a sustainable way that also enables us to understand and mitigate the risks that may emerge. Depending on the purpose of subsurface space use, typical risk challenges may include e.g. impacts to groundwater, oil and gas resources. Expanding uses of the subsurface motivates additional effort to mitigate well-known and relatively new risks. Estimating risk levels in complex systems can be a daunting task if the strategy is to construct simulation models of all known physical processes combined with uncertainties in the system, which for subsurface projects, often dominate the system description. An alternative approach described here isolates the main risk drivers in a high-level probabilistic format known as a Bayesian (Belief) Network (BN). The BN approach accommodates more general relationships between uncertain variables than event or fault trees and allows expression of probabilities to consistently influence the top-level risk indicators. A BN risk model will typically be more compact and legible than its fault/event tree equivalent.

De Jong E.C.W.,DNV KEMA Energy and Sustainability | Vaessen P.T.M.,DNV KEMA Energy and Sustainability
2012 IEEE International Energy Conference and Exhibition, ENERGYCON 2012 | Year: 2012

The introduction of widespread, grid-connected distributed energy resources into distribution grids, including their localised control changes the way in which distribution grids are comprised and ultimately will be managed. To allow for continued, or even improved, reliability of such grids the manner in which the associated equipment's performance is evaluated, tested and validated also needs to change likewise. The performance evaluation of distribution grid equipment under severe grid conditions is presented on three equipment types with mutual interaction and a vision for the future of testing presented. © 2012 IEEE.

Mullen J.D.,University of Georgia | Lamsal M.,DNV KEMA Energy and Sustainability | Colson G.,University of Georgia
Environmental Science and Technology | Year: 2013

This research draws on and expands previous studies that have quantified the costs and benefits associated with conventional roofs versus green roofs. Using parameters from those studies to define alternative scenarios, we estimate from a private, public, and social perspective the costs and benefits of installing and maintaining an extensive green roof in Atlanta, GA. Results indicate net private benefits are a decreasing function of roof size and vary considerably across scenarios. In contrast, net public benefits are highly stable across scenarios, ranging from $32.49 to $32.90 m -2. In addition, we evaluate two alternative subsidy regimes: (i) a general subsidy provided to every building that adopts a green roof and (ii) a targeted subsidy provided only to buildings for which net private benefits are negative but net public benefits are positive. In 6 of the 12 general subsidy scenarios the optimal public policy is not to offer a subsidy; in 5 scenarios the optimal subsidy rate is between $20 and $27 m-2; and in 1 scenario the optimal rate is $5 m-2. The optimal rate with a targeted subsidy is between $20 and $27 m-2 in 11 scenarios and no subsidy is optimal in the twelfth. In most scenarios, a significant portion of net public benefits are generated by buildings for which net private benefits are positive. This suggests a policy focused on information dissemination and technical assistance may be more cost-effective than direct subsidy payments. © 2013 American Chemical Society.

Loading DNV KEMA Energy and Sustainability collaborators
Loading DNV KEMA Energy and Sustainability collaborators