A sustainable production inventory model for profit maximization under optimum raw material input rate during production

A production inventory in bioethanol production consists of three basic segments; raw material ordering, fermentation plant and finished product inventory. A sustainable production process focuses on the optimal utilization of raw materials in order to reduce the negative impact on the environment. In most of the production inventory model, the rate of production is variable which changes with time at a constant amount. In this present paper, an effort has been made to develop a sustainable economic production quantity (EPQ) model with a variable production rate. Although the production rate is dependent on the amount of raw material used for the fermentation process and the rate of fermentation. Further, the production rate is a dependent variable of the maximum input of raw material in the production unit. Model is studied under four different environments; without green investment, with green investment, with variable labour cost and with variable labour cost together with overtime cost. Now to solve the formulated model, weighted particle swarm optimization (Weighted PSO) and constriction factor particle swarm optimization (Constriction PSO) are applied and the optimality is established through statistical analysis and Taguchi L9 design together with the graphical representations of convergence characteristics. Model is validated through numerical examples along with the sensitivity analysis of parameters and managerial implications are provided for effective decision making.