Focus area 4: Cooperation with Saginomiya

1
Trends in Industrial Refrigeration Tim
Kroeger Business Development Manager Industrial
Refrigeration APA
2
Danfoss IR Consensus

• Industrial Refrigeration Conference
• Hosted by Danfoss
• Held in Denmark in 2005
• Trends of the future

3
Developments in IR Main Areas

• Refrigerants
• System design
• Components
• Automatic Controls

4
The Ideal Refrigerant

• Low price
• High efficiency (COP)
• Availability
• Low toxicity
• Low Ozone Depletion Potential (ODP)
• Low Global Warming Potential (GDP)
• High latent heat (to minimise flow)
• Chemical stability

5
Refrigerants for IR - comparison

• properties at 0oC

6
Ammonia NH3

• Longest used refrigerant (since 1872)
• No ODP and GWP
• Very efficient
• Cheap
• Mature product development for components
• Toxic, but early warning
• Limitations due to legislation
• Limited to -40 oC SST

7
Carbon Dioxide CO2

• First mentioned in 1850
• Not used after 1960
• Revival after 1994
• Cheap
• Low critical point
• High triple point
• Special applications (low temp)
• No legal driver in APA
• Special products
• Market share will grow

8
Other Refrigerants

• R723
• 60 ammonia, 40 dimethyl ether
• H-CFCs to be phased out
• HFCs expensive and high GWP
• Hydrocarbons
• Slurry ice
• fish cooling
• Non volatile brines
• Glycol

9
Refrigerants - Summary

• Ammonia to stay on
• CO2 for low temp, growing market share
• No legal driver for CO2 in APA
• HFCs phased out
• Other refrigerants minor role
• Natural Refrigerants growing

10
Danfoss Commitment to Development

• Continuous upgrade of existing products
• pressure ratings of 40 bar
• material compatibility
• New Product Development
• ICS and ICM, ASHRAE award 2005
• ICF, ASHRAE award 2006
• ICMT for CO2 gas cooler
• Electronic Controls
• Ammonia DX
• Liquid level control

11
Industrial Refrigeration System Design

• First Cost - Europe compared to APA
• Operating cost
• Energy Efficiency

12
First Cost

• First Cost main concern
• Growing use of Automatic Controls in APA
• Manually operated plants on their way out
• Still behind Europe
• No PED in APA
• Ammonia DX for high temp

13
Operating Cost and Energy Efficiency

• Cost savings by using automatic controls
• liquid level control
• temperature control
• Labour cost increasing
• phase out of manual controls
• Energy very cheap in Asia
• Stop valves cost more than you think!

14
Commitment to First Cost Saving

• ICF valve station
• Installation cost
• IFC only two weldings!
• No leakage
• factory tested

15
Commitment to Operating Cost Saving

• Low pressure drop components
• STC stop valves, ICM motor valves
• Plant optimisation
• Automatic controls
• Electronics

16
Summary

• First Cost still highest priority
• Consideration for operating cost growing
• More focus on energy efficiency, BUT
• Energy too cheap in APA

17
Legislation

• PED in Europe
• AS 1677 in Australia
• KGSC in Korea
• ...
• Safety standards different
• No push for transition to natural refrigerants

18
Components

• Danfoss Transition from component supplier to
  solution provider
• ICS, ICM, ICF
• Electronics
• Mechatronics (ICAD)

19
Automatic Controls

• By optimising the running conditions of an
  Industrial Refrigeration System, the energy
  efficiency will be increased and therefore the
  running cost minimised
• Automatic control concepts will minimise the
  requirement for personnel attendance
• In many cases, automatic controls will reduce
  random maintenance in the system (inherent plant
  safety)

20
Automatic Controls

• Product Quality is a direct result of the quality
  and reliability of the cooling process and cold
  chain management (from processing to end user)
• Accurate temperature control during processing,
  transport and storage maintains a high product
  quality
• Automatic Controls ensure a high level of safety
  for the operation of Industrial Refrigeration
  Systems

21
Valves vs Automatic Controls

• Valves are installed in a refrigeration system to
  stop the flow of refrigerant to certain sections
  of the plant
• When desired conditions are reached
• When plant maintenance is carried out
• Automatic Controls are installed in a
  refrigeration system to restrict or regulate the
  flow of refrigerant
• To maintain a stable liquid level in vessels
• To maintain accurate temperature
• To manage change in operating status in an
  optimised way (ie defrost)

22
Controls are used for...

• Evaporators
• Temperature
• Superheat
• Defrost
• Compressors
• Suction pressure (ie during start-up)
• Superheat (protection against liquid slugging)
• Suction temperature
• Discharge temperature

23
Controls for...

• Condensers
• Condensing pressure
• Minimise number of start/stops
• Stable conditions to prevent flash-gas
• Vessels
• Maintain stable liquid level
• Ensure liquid supply to evaporators
• Prevent liquid from returning to compressor
• Ensure sufficient head for pumps

24
Manual vs Automatic

• Operator manually opens or closes valves to stop
  or regulate flow of refrigerant
• Operator required at site at all times
• Quality of regulation and therefore efficiency of
  the plant only as good as operator
• Possibility (probability) of human error
• It is impossible to be everywhere at the same
  time

25
Manual vs Automatic

• Slow reaction time when responding to a change in
  operating condition leads to
• Overshooting when reaching set point
  (temperature)
• Inconsistent product quality
• Unstable operation
• Risk of component failure
• Inefficient operation of plant

26
Benefits of Automatic Controls

• Faster response to changes in
• Pressure
• Level
• Temperature
• More accurate control
• Enhanced product quality
• Higher efficiency
• Optimising of operating conditions
• No operator attendance required

27
Benefits of Automatic Controls

• Higher safety
• Less product loss
• Less Maintenance
• Enhanced component reliability
• Less unscheduled repairs

28
Examples of Automatic Controls

• Temperature control
• Liquid level control for vessels
• Hot gas defrost control

29
Temperature Control

• An accurate control concept is paramount for
  ensuring high product quality
• Different control concepts are available
  depending on quality demand

30
Types of Temperature Control

• Manual control
• Mechanical thermostat
• Electronic thermostat
• Electronic pressure control

31
Manual Regulation
32
Manual Regulation

• Advantages
• Cheap

• Disadvantages
• Inaccurate temperature control
• Prone to human error
• No compliance with HACCP
• Affected by ambient conditions

33
Mechanical Thermostat
34
Mechanical Thermostat

• Advantages
• Relatively cheap
• Easy to install
• Automatic operation

• Disadvantages
• Mechanical temperature difference leads to
  inaccuracies in temperature control
• Risk of failure due to wear

35
Electronic Thermostat
36
Electronic Thermostat

• Advantages
• Accurate temperature control
• Display for easy read out
• Incorporation in PLC
• Monitoring

• Disadvantages
• Overswing of temperature due to remaining liquid
  in evaporator

37
Electronic Pressure Regulation
38
Electronic Pressure Regulation

• Advantages
• Most accurate temperature control (within - 0.25
  oC)
• Remote change of set point
• Display
• Monitoring and record via PLC

• Disadvantages
• More expensive than mechanical solutions

39
Electronic Pressure Regulation
40
Evolution
41
Liquid Level Control

• To ensure adequate liquid supply to all
  evaporators
• To accommodate changes in system conditions, e.g.
  Defrost, plant start-up
• Protection of
• Compressors against high liquid levels
• Pumps against low levels causing cavitation

42
Types of Liquid Level Control

• Mechanical
• Manual regulating valve and sight glass
• Float switch and solenoid valve
• Modulating float valve
• Modulating pilot controlled valve
• Electronic Level Control
• Modulating motorised valve with electronic level
  sensor and electronic controller

43
Manual Regulation
44
Manual Regulation

• Advantages
• Cheap

• Disadvantages
• Prone to human error
• No stable suction pressure
• Overshooting

45
Float Switch and Solenoid Valve
46
Float Switch and Solenoid Valve

• Advantages
• Relatively cheap
• Easy to install
• Wide capacity range available
• Float switches for protecting compressors and
  pumps

• Disadvantages
• Less stable level than with modulating control
• No change of set point possible
• Small measuring range

47
Modulating Float Valve
48
Modulating Pilot Controlled Valve
49
Mechanical Modulating Control

• Advantages
• Modulating control
• Very large capacity range
• High side and low side control

• Disadvantages
• No change of set point possible
• More expensive than on-off control
• Does not include safety for compressor and pumps
• More moving parts - more wear and necessary
  maintenance

50
Motor Valve and Electronic Control
51
Mechanical Modulating Control

• Advantages
• Wide measuring range
• Remotely change set point
• Safety for compressors and pumps including alarm
• Very accurate modulating level control
• Ease of commissioning

• Disadvantages
• More expensive than mechanical solutions

52
Evolution
53
Defrost

• Water
• Unsafe, waste of natural resource
• Electrical
• Energy inefficient, risk of fire (insurance)
• Alcove
• High building cost, not suitable for all
  locations
• Hot Gas Defrost
• Energy efficient, fast, safe

54
Hot Gas Defrost
55
Hot Gas Defrost Sequence

• Close liquid supply solenoid valve
• After delay close suction solenoid valve
• Open hot gas solenoid valve
• After defrost termination open suction solenoid
  valve
• two stages to avoid liquid hammer
• Open liquid supply solenoid valve
• After delay start fans

56
Questions
QUESTIONS ?
57
Product Development - ICF

• Complete Control Solutions
• application specific
• Hermetic Design
• factory tested, leak proof
• Service friendly
• reduced service time
• no leakage of ammonia

58
Ammonia Direct Expansion (DX)

• Ammonia Direct Expansion (ADX) reduces the
  refrigerant charge of a refrigeration system
  dramatically (see schematic)
• Ammonia Direct Expansion (ADX) reduces the
  capital cost of a refrigeration system (see
  schematic)

59
History

• First attempts to utilise NH3 in DX systems were
  started in the 1950s, but lack of experience and
  unavailability of automatic controls inhibited
  the development
• Technology resurfaced in late 1990s as a result
  of environmental requirements (reduction of CFCs
  and HCFCs) and availability of equipment
• Availability of miscible oil has greatly enhanced
  the application of NH3 DX systems, even for low
  temperature systems

60
Pump Recirculation System
61
Ammonia DX System
62
Ammonia DX System - Example
63
Ammonia DX System - Example
64
Capital Cost Reduction

• No Surge Drum required
• No Refrigerant Pumps required
• Reduced Refrigerant Charge

65
Challenges Ammonia DX

• Evaporator Design
• Liquid Injection into Evaporator
• Oil Return (Miscibility)

66
Evaporator Design

• Evaporator has to be specifically designed for
  NH3 with regards to
• MSS (minimal stable superheat)
• Heat Transfer Coefficient
• Turbulent Flow
• Oil Return
• Surface bigger than for pump recirculation
• Less than four evaps (guideline)
• Superheat bigger than MSS and smaller than DT

67
Evaporator MSS

• Minimal Stable Superheat (MSS) is characteristic
  of Evaporator and not TX valve
• Superheat can never be lower than MSS
• Superheat can never be higher than DT

68
Evaporator MSS
69
MSS Factors

• Airflow over face area
• Air velocity
• Liquid distribution
• Suction header design
• Heat flux (frost on surface)

70
Liquid Injection Evaporator

• Conventional Mechanical Thermostatic Expansion
  Valve (TX Valve)
• Electronic Expansion Valve (EX Valve)

71
Thermostatic Expansion Valve

• TX Valves are mechanical proportional devices
  which measure the refrigerant flow into the
  evaporator in proportion to the superheat at the
  outlet of the evaporator
• Advantage
• Cost efficient
• Simple
• Disadvantage
• No optimisation
• No PI or adaptive control

72
Electronic Expansion Valve

• Electronic Expansion Valves are electrically
  operated valves which measure the refrigerant
  flow into the evaporator following control
  algorithms
• Either PWM or step motor controlled
• Advantage
• Optimisation
• PI(D) and/or adaptive control
• Disadvantage
• Less cost efficient
• Less simple

73
Operation TX Valve
74
Electronic Expansion Valve
75
Summary

• Evaporators for Ammonia Direct Expansion should
  always be controlled by Electronic Expansion
  Valves to optimise performance
• Evaporators for Ammonia Direct Expansion have to
  be designed very carefully
• I personally do not recommend Ammonia Direct
  Expansion for designated low temperature systems

76
Questions
QUESTIONS ?