Advanced control of heat rejection airflow for improving the coefficient of performance of air-cooled chillers

Optimizing condenser fan control for air-cooled centrifugal chillers

“…The capacity control of the inlet guide vanes in the compressor resulted in the maximum COP at a part load ratio of 0.77 to 0.83 for a constant outdoor temperature. This is contrary to the maximum chiller COP at full load with regard to air-cooled chillers with reciprocating or screw compressors at constant speed [33][34][35][36]. The chiller COP dropped considerably when the chiller load reduced from such part load ratios.…”

“…The model contains an algorithm to compute the required heat rejection airflow and the number and speed of condenser fans based on a set point of condensing temperature. The structure of the model is based on the thermodynamic models used extensively to investigate the energy performance of air-cooled reciprocating or screw chillers [33][34][35][36]. The way to simulate the capacity control of the inlet guide vanes is based on the steady-state model of a centrifugal compressor given in Refs.…”

“…However, very few models have sufficient capability for investigating the controllability of condensing temperature for air-cooled chillers. There are thermodynamic models for air-cooled chillers with reciprocating or screw compressors which are capable of investigating the steady-state behaviour of chiller COP under various operating conditions [33][34][35][36][37][38]. An algorithm is contained in these models to compute the number and speed of condenser fans staged to control the condensing temperature at a specified set point for any given cooling capacity.…”

Modelling of improved energy performance of air-cooled chillers with mist pre-cooling

“…According to many studies [1][2][3][4][5][6][7][8], the deficient performance of air-cooled chillers is mainly due to head pressure control (HPC) under which the condensing temperature floats around a high set point of 50 • C based on a design outdoor temperature of 35 • C, irrespective of different chiller loads and weather conditions. The condenser fan power under HPC can be kept low but with considerable compressor power at such high condensing temperature.…”

Effect of Condenser Air Flow on the Performance of Split Air Conditioner

“…They obtained around 28% increase in cooling capacity and 21.5% improvement in the COP. F. Yu and K. Chan [7] showed how the COP of air-cooled chillers can be improved by modulating heat rejection airflow via variable speed condenser fans. They introduced an algorithm that makes use of a set point of condensing temperature to determine the number and speed of condenser fans staged to provide the airflow required for any given heat rejection.…”