TY - RPRT
T1 - ESO2 Optimization of Supermarket Refrigeration Systems
T2 - Mixed Integer MPC and System Performance
AU - Petersen, Lars Norbert
AU - Madsen, Henrik
AU - Heerup, Christian
PY - 2012
Y1 - 2012
N2 - Supermarket refrigeration systems consists of a number of display cases, cooling
cabinets and cold rooms connected to a central compressor pack. This configuration
saves energy compared to placing a compressor at each cooling site.
The classical control setup of a supermarket refrigeration system is highly distributed.
The cooling sites are equipped with an individual hysteresis controller that keeps the
air temperature in the cooling site within a defined band by manipulating the opening
degree of an inlet valve. The compressor bank maintains a desired suction pressure
by adjusting the capacity to the given load from the cooling sites. An illustration of the
principle is shown in figure 1. This design is flexible and simple, but its major drawback
is however that it introduces self-inflicted disturbances and the dynamic coupling of
the display cases makes them synchronize. Synchronization results in low efficiency
and high wear of the compressor, because the compressor has to work much harder for
short periods of time. The problem increases when the load is small compared to the
available compressor capacity, which it is in the winter time, at night and when only a
few cooling sites are present in the supermarket. The first approach to solve this problem is to design an overall control system which
coordinates the compressor capacity and the current refrigeration load. The drawback
of this approach is the complexity of the single controller. The solution is investigated in
the first part of the report. A second solution is investigated where only the compressor
control is considered. This controller try to feed-forward the measured disturbances, i.e. opening and closing of the cooling site AKV’s. Last a performance analysis of the
refrigeration system is performed.
AB - Supermarket refrigeration systems consists of a number of display cases, cooling
cabinets and cold rooms connected to a central compressor pack. This configuration
saves energy compared to placing a compressor at each cooling site.
The classical control setup of a supermarket refrigeration system is highly distributed.
The cooling sites are equipped with an individual hysteresis controller that keeps the
air temperature in the cooling site within a defined band by manipulating the opening
degree of an inlet valve. The compressor bank maintains a desired suction pressure
by adjusting the capacity to the given load from the cooling sites. An illustration of the
principle is shown in figure 1. This design is flexible and simple, but its major drawback
is however that it introduces self-inflicted disturbances and the dynamic coupling of
the display cases makes them synchronize. Synchronization results in low efficiency
and high wear of the compressor, because the compressor has to work much harder for
short periods of time. The problem increases when the load is small compared to the
available compressor capacity, which it is in the winter time, at night and when only a
few cooling sites are present in the supermarket. The first approach to solve this problem is to design an overall control system which
coordinates the compressor capacity and the current refrigeration load. The drawback
of this approach is the complexity of the single controller. The solution is investigated in
the first part of the report. A second solution is investigated where only the compressor
control is considered. This controller try to feed-forward the measured disturbances, i.e. opening and closing of the cooling site AKV’s. Last a performance analysis of the
refrigeration system is performed.
M3 - Report
T3 - D T U Compute. Technical Report
BT - ESO2 Optimization of Supermarket Refrigeration Systems
PB - Technical University of Denmark, DTU Informatics, Building 321
CY - Kgs. Lyngby, Denmark
ER -