Design and Analysis of an Ammonia/Water Absorption Refrigeration Cycle by Means of an Equation-Oriented Method

Abstract

An equation-oriented model for the design of a simple ammonia/water absorption refrigeration cycle is presented, which due to the nature of the working mixture, includes high-quality thermodynamic and thermophysical property models. There are four versions of the model, depending on heat rejection media and distillation column feed conditions. Solution of the model requires the given variables and designer competence-based variables. The column equilibrium stages, diameter, and height use binary decision variables. The solution of the equation set was developed with a General Algebraic Modeling System (GAMS) general purpose nonlinear solver. An equation solution strategy is described. Once solved, exergy balances are made and irreversibilities and exergy efficiency are calculated globally and for each unit operation. Two examples are compared. The great number of factors that can be varied in the absorption refrigeration system makes manual optimization of an industrial design a formidable task. However, good design makes a decisive difference in regard to the use of waste heat absorption refrigeration. The model forms the basis for the simultaneous optimization of design variables with an appropriate objective function.

Multi-objective optimization of sustainable single-effect water/Lithium Bromide absorption cycle

“…The design problem formulation builds on the work of Chavez-Islas and Heard [8], which focused only on the economic performance of ammonia/water absorption cycle, and of Gebreslassie et al [10]. In the latter, a single-effect ammonia/water absorption cycle was used to provide chilled water at temperatures as high as 5 0 C. However, for this type of application, a water/LiBr solution-supported chiller is superior in its simplicity during the desorption process, the overall performance, and in its capability to be driven at lower temperature [24].…”

“…While rigorous mathematical optimization approaches have been applied widely in design optimization of other industrial processes [6,7], such approaches have not seen widespread application in the design of cooling systems; recently, optimization of ammonia/water absorption cycles has been reported [8][9][10]. The design task is posed as an optimization problem and solved using standard techniques for linear, nonlinear, mixed integer linear and mixed integer nonlinear (LP, NLP, MILP, MINLP, respectively) problems.…”

Optimum heat storage design for solar‐driven absorption refrigerators integrated with heat exchanger networks

“…To reduce the anthropogenic GHGE and the harmful climate change effects caused by them, several governments around the world have implemented incentive policies, such as carbon tax credits and subsidies, for stimulating the investment in clean and renewable energy related technologies to increase their deployment. In this context, Chavez‐Islas et al proposed an approach for designing ammonia‐water AR systems, while Florides et al modeled an absorption solar cooling system, Assilzadeh et al introduced a methodology for a solar cooling system using evacuated tube solar collectors and LiBr absorption unit, Lecuona et al determined the optimal hot water temperature that maximizes the efficiency of a chiller, Fathi et al studied the effect of the variables that affect the coefficient of performance ( COP ) of absorption refrigerators and Wu et al presented optimization formulations for designing AR systems. Additionally, mathematical programming approaches have been proposed to design energy systems (i.e., Savola and Fogelholm et al presented a MINLP model for increasing the power production in small scale; Tveit et al proposed a MINLP model for analyzing new investments and operation of CHP plants and Hamed et al carried out the optimization of an absorption refrigerator in dynamic mode).…”

Integration of Renewable Energy with Industrial Absorption Refrigeration Systems: Systematic Design and Operation with Technical, Economic, and Environmental Objectives

“…Regarding the cooling cycles, they usually have been optimized as separate components (e.g., Florides et al, , Assilzadeh et al, Lecuona et al, Fathi et al, and Wu et al). In addition, mathematical programming approaches have been proposed for the design of energy systems (see Savola and Fogelholm and Tveit et al) and for ammonia–water absorption cycles (Chavez-Islas et al − ). Recently, some methodologies have been proposed to address the refrigeration process considering the economic and environmental aspects simultaneously. − …”