Advanced Method of Variable Refrigerant Flow (VRF) System Design to Forecast on Site Operation—Part 3: Optimal Solutions to Minimize Sizes

Abstract

Outdoor air conditioning systems (ACS) are used as autonomic systems as well as in combined outdoor and indoor ACS of the variable refrigerant flow (VRF) type, with variable speed compressors (VSC) as their advanced version. Methods for determining the optimal value of refrigeration capacity and providing the maximum rate of the summarized annual refrigeration energy generation increment, according to its needs at minimum compressor sizes and rational values, are applied to reveal the reserves for reducing the designed (installed) refrigeration capacity, thus enabling us to practically achieve maximum annual refrigeration energy generation as the primary criterion at the second stage of the general design methodology previously developed by the authors. The principle of sharing the total thermal load on the ACS between the ranges of changeable loads for outdoor air precooling, and a relatively stable load range for further processing air are used as its basis. According to this principle, the changeable thermal load range is chosen as the object for energy saving by recuperating the excessive refrigeration generated at lowered loading in order to compensate for the increased loads, thereby matching actual duties at a reduced designed refrigeration capacity. The method allows us to determine the corresponding level of regulated loads (LRL) of SRC and the load range of compressor operation to minimize sizes.

Research of hydrodynamic processes in the flow part of a low-flow thermopressor

“…A general way to increase the efficiency of power plants is to utilize the exhaust heat [1][2][3] and cool the working fluid [4] to provide favorable conditions for their efficient operation by application of waste heat recovery chillers [5,6] or electrically driven vapor compression refrigeration machines as in air conditioning system [7,8]. The air is a general working fluid in the majority of the power plants based on combustion engines, in particular, gas turbines [9,10], internal combustion engines [11,12], as well as in air conditioning systems as subsystems which provide processing (cooling) engine intake air or as autonomous systems in stationary [13][14][15] and transport application [16,17]. The various types of heat exchangers and feeding circuits are used for cooling air [18][19][20].…”

Increasing the Efficiency of Turbine Inlet Air Cooling in Climatic Conditions of China through Rational Designing—Part 1: A Case Study for Subtropical Climate: General Approaches and Criteria

“…In contrast to comfort (space) air conditioning [71,72] with annual refrigeration energy production in response to its consumption as a criterion [73,74], in engine cyclic air cooling, the annual fuel reduction is applied as criterion [57,75] to determine the rational capacities to achieve maximum output.…”

Innovative approaches and modified criteria to improve a thermodynamic efficiency of trigeneration plants

“…There are many methods applied to optimize the heat loads on exhaust heat utilization and air-cooling systems [45,46] in order to mееt actual loading [47,48], gain a maximum output [49,50] and improve operation performance of engines [51,52]. They focus to enhance output of engines due to sucked air cooling at varying actual ambient temperatures [53,54].…”