BITZER RECIPROCATING COMPRESSORS FOR CO2

APPLICATIONS

BITZER Kühlmaschinenbau GmbH

Oliver Javerschek

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TABLE OF CONTENTS

1. Preface

2. Important Aspects of CO2 Applications

3. Why BITZER?

4. Conclusions

Preface

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COMMERCIAL REFRIGERATION WITH CO2:

NUMBER OF INSTALLATIONS

Reference: * Estimation of Shecco, ATMOSphere Europe 2015, BITZER

>68 / 114

--- / > 46

≈ 4000 / ≈ 2000

≈ 600 / 18

>30 / ≈ 10

≈ 3 / > 200

Transcritical

systems with

CO2: >5000 *

Subcritical

systems with

CO2: >3000BITZER: > 45 000 sold CO2 compressors,

mainly in commercial refrigeration!

Important Aspects of CO2 Applications

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Booster system with common refrigerant circuit:� “Exchange” of heat energy, refrigerant mass flows & lubricant� Externally compounded two stage system, two stage expansion� Flash gas bypass

DEFINITION OF CO2 PROCESS CYCLES

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OPERATING TEMPERATURES IN A BOOSTER

SYSTEM

/ High MT load and low LT load

� Low RGT for MT compressors

� Influence of FGB on RGT

/ Low MT and high LT load

� High RGT for MT compressors

Worst Case Scenarios on Load Conditions: MT / LT

140 °C

130 °C

40 °C

30 °C

140 °C

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CAPACITY REGULATION

4HTC-20K @ t gc out 38 °C, to -8 °C, Toh 10 K = 23,4 kW

(100 %)

4HTC-20K @ tc 10 °C, to -8 °C, Toh 10 K = 47,0 kW (200 %)

Capacity regulation is

essential for CO2

applications:

full load = „easy“ & part

load = „challenging“

CR with 4KTC-10K, to -8 °C, Toh 10 K, f 65 .. 35 Hz, Qo ≈

const.

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PARALLEL VS. FG - BYPASS SYSTEM

Influence on the operating conditions of the MT compressor stage

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PARALLEL VS. FG - BYPASS SYSTEM

Lower heat sink temp. =

lower head pressure =

reduction of flash gas =

lower frequency

(capacity) of the parallel

compressor

Influence of reduced heat sink temperatures

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PARALLEL VS. FG - BYPASS SYSTEM/ Application of an IHX (gas cooler outlet ↔ FGB) or other measures

● Significant difference for the MT suction: Parallel compression vs. FGB ● Avoiding wet operation during FGB operation

● Transition from parallel compression to FGB operation● Emergency operation with high heat sink temperatures

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COP DEPENDENT ON AMBIENT TEMPERATURE

Based on:

Qo MT 20 kW @ - 8 °C / Qo LT 3 kW @ -32 °C, 40 bar medium pressure, ASHRAE 2009, Weather Data Viewer 4.0

Why BITZER?

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SERVICES AND TRAINING

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BITZER SOFTWARE TOOLS AND

DOCUMENTATION

Reference: Mark Twain, A Winning Hand

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Undersquare stroke-bore ratios

All bearing seats feature

large surfaces

Multi-layer bearings

Specially treated piston surfaces, low average piston velocities, low pressure reduction per piston ring

Enforced connecting rods incl. bearings

Piston pin largely

dimensioned & large seating

WHY BITZER? EXPERIENCE IN ADVANCED

COMPRESSOR DESIGN!

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WHY BITZER? EFFICIENCY!

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BITZER COMPRESSORS FOR CO2

APPLICATIONS

tc max = 15 °C

The well-proven SL range for subcritical

applications with CO2 as refrigerant

/ LT stage of a cascade (hybrid) system

/ LT stage of an all CO2 booster system

/ MOP: HP 53 bar / LP 30 bar

to max = -15 °C

Compressors for transcritical applications

with CO2 as refrigerant

/ MT stage of an all CO2 booster system

/ CO2 heat pump system

/ ECO compressor in an parallel compression system

The new ME range for subcritical applications

with CO2 as refrigerant

/ MT application with high condensing temperatures

/ LT stage of an all CO2 booster system with a high

demand on standstill pressures

/ MOP: HP 100 bar / LP 100 bar

/ Two motor versions

tc max = 25 °C

to max = 0 °C

T: Transcritical applications

ME: High condensing and

high standstill pressures

SL: Low temp.

applications

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BITZER CO2 COMPRESSORS - CERTIFIED

PRODUCTS!

/ Since three years BITZER is the only manufacturer

/ 17 models for subcritical CO2 applications (2011)

/ 9 + 3 models for transcritical CO2 applications (2012, 2015)

Conclusions

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CONCLUSIONS

Premise for a successful CO2 installation:

/ Observation of operating temperatures

/ Correctly balanced capacity regulation

/ Focus on annual energy efficiency

BITZER provides the most beneficial CO2 compressor offering:

/ Three product families for a wide field of CO2 applications

/ Technical documentation and software

/ Technical training, individual support and special services

BITZER CO2 compressors set new standards and show the benchmark

/ Trendsetting technology

/ Highest efficiency and reliability

/ ASERCOM certified products