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Engine Oils and Their Evaluation/Engine Lubrication Aspects
Published in Wilfried J. Bartz, Engine Oils and Automotive Lubrication, 2019
Multi-valve gasoline engines rely on two or four overhead camshafts for their high performance and fuel economy. The Sequence V-D test introduced in 1980 used a 2.3-liter single overhead-camshaft engine. In this test, the blow-by rises through the oil drain holes in the cylinder head and exits out the rear end of the rocker cover. The blow-by then passed through an external heat exchanger – maintained at engine coolant temperature – and finally exits through the positive crankcase pressure valve. This engine configuration made it easy to divert the engine blow-by from the camshaft. The gaseous phase of the blow-by was collected and analysed by high resolution mass spectrometry. C. T. West et al. postulated that wear in the V–D test is corrosive. Analysis of high wear parts at the end of the test indicates an abrasive wear mechanism. Lack of the proper wear films probably results in a two–body abrasion.
Monarch Butterfly Optimization-Based Computational Methodology for Unit Commitment Problem
Published in Electric Power Components and Systems, 2021
Case 2: In a real power plant, when the steam admission valve opens, the fuel cost increases suddenly due to the wire drawing effect it makes the cost function of the problem non-differentiable, non-linear, and non-convex. Thus, to make the production cost of thermal generators suitable for real power system problems, this effect is brought into objective function as VPL effect of multi-valve thermal turbines as follows: where VPE represents the VPL effect.
Optimal power flow control optimisation problem incorporating conventional and renewable generation sources: a review
Published in International Journal of Ambient Energy, 2023
T. Papi Naidu, G. Balasubramanian, B. Venkateswararao
Objective 2: The cost of Real power generation cost with respect to the valve-point effect was considered to have a more operative and accurate cost function model. With regard to the impact of multi-valve turbines, the power systems show a larger deviation in the cost of generation and sinusoidal function upgraded to fuel costs. where
Profit based unit commitment problem solution using metaheuristic optimisation approach
Published in International Journal of Systems Science: Operations & Logistics, 2023
V. Kumar, R. Naresh, Veena Sharma
In this strategy, GENCO receives the reserve power payment for any period of time whether used or not, and thus the reserve price is much lower than the spot price. If the reserve is used in any hour, GENCO will receive the spot price for the reserve power produced, whereas it will receive the reserve price for those hours in which reserve is allocated but not used. Consequently, GENCO total revenue from energy and ancillary services in strategy B is expressed as: GENCO’s total cost remains the same as the strategy A cost. Accordingly, GENCO’s total profit in strategy B is given as follows. The cost of generated energy per hour for ith unit is expressed as Here VPE represents the valve point loading effect. In a real power plant, when the steam admission valve opens, the fuel cost increases suddenly due to the wire drawing effect. It makes the cost function of the problem non-differentiable. Thus, to make the production cost of thermal generators suitable for real power system problems, VPE is used and it is modelled as a rectified sine curve for a multi-valve steam turbine. The sinusoidal term considered causes ripples to heat rate curve, and therefore it creates many local minima in search space. To handle the nonlinearity due to VPE, the linearisation procedure is adopted, which is as follows: Subject to: where and are linearised VPE coefficients; is the output power of ith thermal unit within the segment m; is binary variable; m is an index of the linear segment and is the total number of parts on piecewise linear functions with VPE. and are modified minimum and maximum power limits. We calculate parameters , and used in above equations as follows: where fi is valve point coefficient of unit i, and value of M is taken as 2.