Takashi Shiba

Optimal Operation of a Cogeneration Plant in Combination With Electric Heat Pumps

An operational problem is discussed for a gas turbine cogeneration plant in combination with a heat pump/thermal storage system that utilizes time-of-use pricing of the electrical utility. An optimal planning method is presented by which the operational policy of constituent equipment is determined so as to minimize the daily operational cost. An algorithm is proposed to solve this optimization problem efficiently by combining the dynamic programming method with the mixed-integer programming one. A case study is carried out to investigate the effect of introducing a heat pump system into a cogeneration plant.

An Optimal Operational Advisory System for a Brewery’s Energy Supply Plant

An optimal operational advisory system is proposed to operate rationally a brewerys energy supply plant from the economical viewpoint. A mixed-integer linear programming problem is formulated so as to minimize the daily operational cost subject to constraints such as equipment performance characteristics, energy supply-demand relations, and some practical operational restrictions. This problem includes lots of unknown variables and a hierarchical approach is adopted to derive numerical solutions. The optimal solution obtained by this methods is indicated to the plant operators so as to support their decision making. Through the numerical study for a real brewery plant, the possibility of saving operational cost is ascertained.

Optimal Planning of a Cascade-Type Multistage Refrigeration System for a Beverage Plant

An optimal planning method is presented for a cascade-type multistage refrigeration system. Heat exchange areas of evaporator, condenser, and beverage cooler are determined optimally so as to minimize the annual total cost and input energy consumption subject to constraints concerning annual equipment operation. This problem is considered as a multiobjective optimization one, and a discrete set of Pareto optimal solutions is derived numerically by a weighting method. Through a numerical study, it is investigated how the heat exchange areas influence the long-term economics and energy conservation. Cascade-type multistage refrigeration systems are compared with single-stage systems.

Optimal Operational Planning for a Heat Pump Space Cooling System with Ice Bank Based on the Log Barrier Method.

An optimal operational planning problem is discussed for a heat pump space cooling system considering characteristics in ice bank during ice making and thawing. This problem is formulated as a mixed-integer nonlinear programming one, in which the operational strategy of heat pumps and ice bank is determined so as to minimize the daily operational cost. An algorithm is proposed to solve this optimization problem on the basis of the log barrier method. Through a numerical study, it is ascertained that the proposed algorithm is a useful tool, and it is investigated how the characteristics in ice bank influences on the operational strategy.