COMPACT CO2/NH3 REFRIGERATIONREFRIGERATION

UNIT FOR THE COLD STORAGE

WITH USEING CO2 FORCED CIRCULATION SYSTEM

TOYO ENGINEERING WORKS.LTD

C-dig meeting : 28 August 20072

・・In the first half, I introduce a compact CO2/NH3 In the first half, I introduce a compact CO2/NH3

refrigeration unit for the cold storage. refrigeration unit for the cold storage.

・・In the second half, I introduce aIn the second half, I introduce a cold storage cold storage ・・In the second half, I introduce aIn the second half, I introduce a cold storage cold storage

exhibition system of the mammoth in the Aichi exhibition system of the mammoth in the Aichi

world exhibition, although it is not in agenda. world exhibition, although it is not in agenda.

TOYO ENGINEERING WORKS.LTD

1

Introduction

We have constructed many cold storage warehouse with a small

water cooled condensing unit "LTS" in Japan from 25 years ago.

Like this, we have delivered many LTS. Therefore, it is

necessary that shall be renewal the aged LTS and also

HCFC refrigerant.

Refrigerant of this unit is the HCFC-22.

Therefore, we developed CO2/NH3 circulation system "C-

LTS". The development point in the renewal is to make the unit

compactly.

We think､､､､ it is necessary to diffuse the natural refrigerant

system for earth environment.

HCFC refrigerant.

3

Example that Used the LTS Unit

・・・・This example shows the LTS unit at the outside

of a cold storage warehouse of every floor.

Water Cooling Tower

LTS

UnitCold Storage

Warehouse

Unit

・・・・The system is a direct expansion refrigeration of the HCFC-22.

・・・・The cold room temperature is the range of minus 30 degrees

from minus 5 degrees.

・・・・There are many LTS unit in one cold storage warehouse,

because a small unit needs no maintenance person in law.

・・・・We delivered about 5,000 units in Japan. 4

Example that Used the LTS Unit

LTS

・・・・This example shows one LTS unit in the upper side

vacancy of the freezing room entrance.

LTS

Unit

Cold

Room

5

Example that Used the LTS Unit

・・・・This example shows the plural LTS unit in a machine room.

6

LTS

Unit

Series of CompactSeries of Compact CC--LTSLTS

ModelsModels 220F220F--WPWP 370F370F--WPWP 550F550F--WPWP

Cooling Capacity [kW]Cooling Capacity [kW] 32 / 3832 / 38 52 / 6352 / 63 72 / 8772 / 87

Shaft Power [kW]Shaft Power [kW] 20 / 2420 / 24 31 / 3731 / 37 43 / 5143 / 51

Power SupplyPower Supply AC 3φAC 3φ××××××××200V200V××××××××5050／／／／／／／／60 Hz60 Hz

RefrigerantRefrigerant ／／／／／／／／RefrigerantRefrigerant NH3NH3／／／／／／／／CO2(Secondary Refrigerant)CO2(Secondary Refrigerant)

Comp.Comp. TypeType Open type TwoOpen type Two--stage Screwstage Screw

Motor Rated Motor Rated Power [kW]Power [kW]

2222 3737 5555

CO2 pump [kW]CO2 pump [kW] 0.150.15 0.150.15 0.150.15

Size : WSize : W××××××××LL××××××××H [m]H [m] 1.51.5××××××××2.52.5××××××××1.91.9 1.61.6××××××××2.72.7××××××××2.02.0 1.61.6××××××××3.03.0××××××××2.02.0

Weight [kg]Weight [kg] 2,6002,600 3,7003,700 4,0004,000

7

Cascade

Condenser

NH3

Compressor

NH3

Condenser

CO2/NH3 System

Flow Sheet

Schematic diagram of system flow

C-LTS

UNIT

1

Condenser

NH3

Receiver

CO2

Receiver

CO2

Pump

Evaporator

Expansion

Valve38

Outside Photograph of Compact C-LTC

New model

9

NH3 Compressor

NH Condenser

Cascade condenser

CO2 Receiver

Inside of Compact C-LTC

NH3 Condenser

NH3 Receiver10

Cascade condenser

CO Receiver

CO2 liquid

outlet

CO2 Receiver

NPSH=800mm

11CO2 Liquid pump

NPSH : Net positive suction head

We make Compact CWe make Compact C--LTS smaller than LTS smaller than

prototype CO2/NH3 unit.prototype CO2/NH3 unit.

New Compact CNew Compact C--LTSLTS40% Volume Decrease

Prototype CO2/NH3 Prototype CO2/NH3

circulation unitcirculation unit

1.9m1.9m××××××××3.8m3.8m××××××××3.5mH3.5mH 1.5m1.5m××××××××2.5m2.5m××××××××1.9mH1.9mH

New model

As a result, the size of compact CAs a result, the size of compact C--LTS LTS

became equal with the old HCFCbecame equal with the old HCFC--LTS.LTS.12

Method for Downsizing

／／／／Adoption of a CO2 Subcooling System

・・・・A CO2 Subcooling System has the biggest effect for downsizing.

・・・・The CO2 liquid of the receiver is cooled by the evaporation

of NH3.

・・・・The purpose of subcooling is to make NPSH of the CO2 liquid

pump smaller. (NPSH : Net positive suction head)

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pump smaller. (NPSH : Net positive suction head)

・・・・In this way, we can reduce the height of the unit.

・・・・The NPSH of the CO2 liquid pump is 1.4 m.

・・・・The subcooling degree of 1K is equal to NPSH of

about 3.5 m.

・・・・The subcooling of the CO2 liquid is effective to "the reduction

of necessary NPSH" and "the downsizing of the unit".

10.0

20.0

30.0

ooler temperature、℃

10

15

lectric currunt value of CO

2 liquid

C ooler w ind

Electric current value of C O 2 liquid pum p

The example of the operation condition without subcooling

(1)

Cooler air

temperature Current value of CO2

liquid pump

Relationship Electric current value of C O 2 liquid pum pto cooler tem perature (N o super cooling)

-30.0

-20.0

-10.0

0.0

10.0

1 301 601 901 1201 1501 1801

Tim e、m in

Cooler temperature

0

5

10

Electric currunt value of CO

pump、A

14

Cavitation

0.0

5.0

10.0

15.0

、℃

10

15

Electric current value of CO

2 liquidC ooler w ind

The example of the operation condition with subcooling

(a)

Cooler air temperature

Relationship Electric current value of C O 2 liquid pum p and cooler w ind tem perature

(Super cooling)

-30.0

-25.0

-20.0

-15.0

-10.0

-5.0

0.0

0 10 20 30 40 50 60

Tim e,m in

Cooler temperature、℃

0

5

10

Electric current value of CO

pump 、A

Electric current value of C O 2 liquid pum p

15

Stable driving

Current value of CO2

liquid pump

Characteristic of CompactCharacteristic of Compact CC--LTSLTS

• We use the natural refrigerant (CO2 and NH3) that defends

earth environment ／／／／ODP is a zero and GWP is 1 or less.

• We can renewal from HCFC-LTS to C-LTS with a compact

design.

3. We can keep highly safe by supplying CO2 to a load side and 3. We can keep highly safe by supplying CO2 to a load side and

minimum charge of NH3 in the unit.

4. Comparison with a brine (Ex. Ethylene glycol) system by NH3

cooling

1) Pump power is smaller／／／／Because it uses the latent heat of CO2

2) Brine control is unnecessary

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