Abstract; Introduction - Emerson E2 User Manual

OPTIMUM REFRIGERATION CONTROL WITH E2™

ABSTRACT

This article discusses the control of modern supermarket refrigeration systems
using state of the art digital refrigeration controllers manufactured and marketed by
Computer Process Controls (CPC), under the "E2" name. This family of refrigeration
controllers was designed to provide precise refrigerated product temperature control
while minimizing refrigeration system energy and maintenance expenses.
controllers, and their predecessors, have been in use in supermarkets throughout the US
and world for more than twenty years.
theoretical analysis done using sophisticated refrigeration models developed by
Emerson, and include information about energy and product shrink savings that CPC
users have experienced since the introduction of these refrigeration controllers to the
supermarket industry.

INTRODUCTION

Supermarkets operate on very thin profit margins. Any reductions in energy,
maintenance or product shrink expense directly improves supermarket profits.
energy required to refrigerate perishable food products accounts for a substantial portion
(more than 30%) of an average supermarket's total electric energy usage and expense.
Installing carefully designed mechanical systems that include efficient compressors,
condensers and refrigerated fixtures does not guarantee optimum fixture temperature
control, maximum refrigeration system energy efficiency and lowest refrigeration system
operating expenses. This is because refrigeration systems seldom run at their design
load, and are often ineffective and inefficient at part load conditions.
matching refrigeration system capacity to the real and varying refrigeration loads found in
all supermarkets, and the control systems required to accomplish this task, are the most
important factors for high overall refrigeration system performance and low overall
refrigeration system operating expenses.
A typical refrigeration system consists of at least one display case with a
refrigerant metering device (expansion valve), a compressor, and a condenser (see
figure 1). The system may also be fitted with fixture suction pressure regulators between
the refrigerated fixture(s) (refrigerated display cases and storage boxes) and
compressor(s), as well as other mechanical and electromechanical refrigeration control
valves. The primary objective of any refrigeration control system is to achieve the
desired fixture and product temperatures.
designers, manufacturers, and operators is to find effective ways to modulate the system
compressors, condenser fans, expansion valves, pressure regulators, and other
components to achieve stable and reliable system operation and high system operating
efficiencies while at the same time closely controlling refrigerated fixtures and products
to these desired temperatures. Defrost and defrost control is also necessary for the
operation of any real refrigerated fixture, along with control of anticondensate heaters
that are a part of most glass door and some other types of refrigerated display case. The
refrigeration system controllers should be able to provide efficient control of these
system elements as well.
The findings outlined below are based on
The challenge for refrigeration system
The E2
The
Therefore,
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