Johnson Controls York YKEP Series User Manual

FORM 160.77-O2
ISSUE DATE: 11/15/2011
JOHNSON CONTROLS
7
11
CHILLER PRINCIPLE OF OPERATION
The YKEP chiller (Figure 1 on Page 7) consists
of the components of a standard high pressure single
stage centrifugal chiller plus the addition of a flash
economizer and a secondary compressor to draw flash
gas from the economizer when required and discharge
to the condenser. The secondary compressor is referred
to as the economizer compressor. A system diagram is
shown in Figure 2 on Page 8.
The chiller operates in three configurations depending
on the lift required and the load.
1. The primary compressor can operate indepen-
dently with the economizer off, drawing suction
from the evaporator, discharging to the condenser,
with condensed liquid return to the evaporator via
ow through the idle economizer. The discharge
of the economizer compressor includes a check
valve to prevent backow from the condenser to
the economizer vessel in this operating mode.
2. When the calculated gas ow through the primary
compressor reaches a prescribed threshold as fol-
lows, the economizer compressor start is initiated.
The economizer compressor draws suction from
the economizer vessel and discharges to the con-
denser. The economizer compressor capacity is
controlled to maintain the economizer pressure at
a target value between the condenser and evapo-
rator pressures. In this mode the chiller is econo-
mizing to gain refrigeration effect for the primary
compressor and improve efciency.
Economizer compressor start criteria:
Primary Compressor Calculated Flow ≥ Flow Target de-
fined as a straight line between the points.
• Saturation Pressure of Subcooled Liquid - Evapo-
rator pressure = 64 PSID: 6000 CFM Required
• Saturation Pressure of Subcooled Liquid - Evapo-
rator Pressure = 30 PSID: 8200 CFM Required
Additionally:
• The Economizer Liquid Level must be below 90%
• The Leaving Chilled Liquid Temperature is not be-
low Setpoint
• The Economizer Saturation Temperature is not
below the Target Temperature
FIGURE 1 - YKEP SYSTEM COMPONENT IDENTIFICATION
LD15301
EVAPORATOR
CONDENSER
PRIMARY (K7)
COMPRESSOR
PRIMARY
OPEN-DRIVE
MOTOR
ECONOMIZER
OPEN-DRIVE
MOTOR
CONTROL
CENTER
ECONOMIZER (Q3)
COMPRESSOR
SUBCOOLER
VALVE
ISOLATION
VALVE
ECONOMIZER
COMPRESSOR
SOLID STATE
STARTER
ECONOMIZER
OIL PUMP
HOUSING
OIL PUMP
PANEL
SECTION 1 - YKEP CHILLER OVERVIEW

Johnson Controls York YKEP Series Specifications

General

Brand	Johnson Controls
Model	York YKEP Series
Category	Chiller
Language	English