Next-generation Ejector Cycle for Truck-transport Refrigerator

1. Next-generation Ejector Cycle
for Truck-transport Refrigerator
Etsuhisa Yamada,
Haruyuki Nishijima, Hideya Matsui,
Toshio Ueno, Masami Taniguchi,
Akira Fujita
DENSO CORPORATION

2. Contents
1. Background
2. Next-generation Ejector Cycle System (EJECS)
3. Application Challenges
4. Solutions
5. Test Results
6. Future Possibilities for EJECS
2

3. 1. Background
3

4. Development Background
2002 2004 2006 2008
World first
World first
Large truck
Large truck Packaged type Expansion
Packaged type Ejector type
(6-ton class)
(6-ton class) (450 mm (H))
(450 mm (H)) valve type (Original EJECS)
Jun.
Thin type
Thin type Expansion
(125 mm (H))
(125 mm (H)) Valve type
Medium-size
Medium-size Packaged type
Packaged type Expansion Ejector type
truck
truck (450 mm (H))
(450 mm (H)) valve type (Original EJECS)
(4-ton class)
(4-ton class) Sep.
Thin type
Thin type Expansion
(125 mm (H))
(125 mm (H)) valve type
World first
World first
Small truck
Small truck Thin type
Thin type Expansion New ejector type
(2-ton class)
(2-ton class) (125 mm (H))
(125 mm (H)) Valve type (Next-generation EJECS)
Jan.
4

5. Newly Developed Refrigerator
Compressor Condensing unit
Compact freezer truck
Cooling unit Ejector and main components
125 mm (H)
Cold Air
5

6. Field Test Results
Annual fuel consumption [L] 5% 27% reduction on refrigerator
Refrigerator
on
Vehicle
Vehicle Refrigerator
off
Developed Conventional
refrigerator refrigerator
6

7. 2. Next-generation Ejector Cycle
System (EJECS)
7

8. Need for Next-generation EJECS
Original Ejector Cycle Refrigerator
Condenser Ejector
Compressor
Engine Evaporator
Accumulator
(300 mm (H))
Packaged-type refrigerator has sufficient
space to house EJECS with accumulator.
8

9. Need for Next-generation EJECS
Original Ejector Cycle system
Expansion Condenser
valve Compressor
Two-phase
Ejector refrigerant Gas
Evaporator Accumulator
Accumulator
Distribution
Retention
Liquid
9

10. Need for Next-generation EJECS
Original Ejector Cycle system
Most Critical Issue
Most Critical Issue
Necessary to eliminate accumulator in
Necessary to eliminate accumulator in
order to develop thin type refrigerator.
order to develop thin type refrigerator.
10

11. Idea for Accumulator Elimination
Distribution Receiver
High-pressure
High-pressure
side
side Condenser
Compressor
Gas
Ejector
Low-pressure
Low-pressure Accumulator
side Distribution
side
Retention
Evaporator
Liquid
11

12. Idea for Accumulator Elimination
Technological Point
Technological Point
To switch accumulator function from
To switch accumulator function from
low-pressure side to high-pressure side
low-pressure side to high-pressure side
12

13. Configuration
Receiver
Receiver
Condenser
Expansion
valve
Compressor
Intermediate
Pressure
Suction flow
pressure
Flow control
Drive flow valve
Nozzle
Air Upwind
Upwind
evaporator
evaporator
Downwind
Downwind
evaporator
evaporator
Enthalpy
13

14. Configuration
Receiver
Receiver
Condenser
Expansion
valve
Compressor
Intermediate
Pressure
Suction flow
pressure
Flow control
Drive flow valve Pressure
Air rise
Nozzle
Two-temperature
evaporator
Enthalpy
14

15. Benefits
Intermediate
Less compressor
Less compressor
pressure
power
power
Iso-entropy line
Suction Drive flow
flow
Pressure rise
Pressure rise
Recovered
Recovered
expansion energy
expansion energy
Improved refrigeration performance
Improved refrigeration performance
15

16. Breakdown of COP Improvement
Decreasing
Decreasing
compression ratio
compression ratio
Improved compressor
Improved compressor
COP improvement [%]
efficiency
efficiency
Compressor
Half refrigerant flow
Half refrigerant flow
to evaporator
to evaporator
Ejector Evaporator
Reduced pressure loss
Reduced pressure loss
Ejector pressure rise
Ejector pressure rise
Compressor power
Compressor power
savings
savings
&
&
Next-generation increased cooling
increased cooling
EJECS capacity
capacity
16

17. 3. Application Challenges
17

18. Challenges
Flow control
assembly
Ejector
Pressure
Drive flow rise
Suction flow Two-temperature
evaporator
Flow Control Assembly Challenge
→ To produce ejector benefits at low cost
Two-temperature Evaporator Challenge
→ To design based on pressure rise
18

19. 4. Solutions
4.1 Flow Control Assembly
4.2 Two-temperature Evaporator
19

20. Flow Control Assembly
Control Heavy load
valve (summer conditions)
Ejector
Pressure rise
Low load
(winter conditions)
Drive
flow Increasing
Pressure
Pressure Increasing
Suction rise pressure rise
pressure rise
Ejector rise
flow nozzle
Increasing
Increasing
drive flow energy
drive flow energy
Decreasing
Decreasing
flow ratio
flow ratio Flow ratio
(suction/drive)
20

21. Flow Control Assembly
Expansion
valve
Flow Control Assembly
Flow Control Assembly
Separating
block Separating
Capillary block
tube
Nozzle Intermediate
(fixed throttle) pressure
Ejector
Ejector
Expansion
Capillary tube valve
(fixed throttle)
Fixed throttles enable appropriate flow control at low cost.
21

22. 4. Solutions
4.1 Flow Control Assembly
4.2 Two-temperature Evaporator
22

23. Differences from Conventional Evaporator
Upwind Decrease in temp. difference
Decrease in temp. difference
evaporator between refrig. & air
between refrig. & air
Downwind Air temp.
Pressure
evaporator
Refrigerant temp.
Pressure rise
Increase in pressure losses
Increase in pressure losses
Decrease in heat transfer coefficient
Decrease in heat transfer coefficient
at the refrig. side
at the refrig. side
Enthalpy
23

24. Solutions
Upwind Evaporator
Upwind Evaporator
Increased upwind evaporator efficiency.
Decreased refrigerant-side pressure losses.
Downwind Evaporator
Downwind Evaporator
Increased refrigerant-side heat transfer coefficient.
24

25. Configuration of Two-temp. Evaporator
4 stages
2 stages (rows)
Upwind
(rows)
evaporator
Air
5 paths
Downwind
evaporator
Revolving
2 paths
distributor
25

26. 5. Test Results
26

27. Ejector Pressure Characteristics
Internal temperature: -22° C
Ejector pressure rise Compressor speed: 1020 rpm
Stable pressure rise
-20 -10 0 10 20 30 40 50
Ambient temp. [deg. C]
27

28. Power Saving Advantages
Internal temperature: -18° C
-50
Power-saving effects [%]
-35% -34%
-32% -31% -30% -30%
-40 -29%
-30
-28%
-27%
-20 -24% -22% -25% -23%
-22%
00 m]
-10 -17% 25 [rp
-9% -8% -8% -11% -10% -12% 20 ed
19 pe
0 s
20 or
5 15 25 35 10 ss
e
External temp. [deg. C] pr
C om
28

29. Field Test Result
Annual fuel consumption [L] 5% 27% reduction on refrigerator
Refrigerator
on
Vehicle
Vehicle Refrigerator
off
Developed Conventional
refrigerator refrigerator
29

30. Advantages
COP
COP Cooling
Cooling Refrigerant
Refrigerant
improvement
improvement capacity
capacity saving
saving
At same Ambient temp. 35° C
cooling capacity Internal temp. -18° C
+32%
+12%
-11%
Better
Better
Better
1.32
1.12
1.0 1.0 1.0
0.88
Next-generation Expansion Next-generation Expansion Next-generation Expansion
EJECS valve system EJECS valve system EJECS valve system
30

31. Conclusions
• Next-generation EJECS developed and released for
small truck refrigerators.
• 32% COP improvement over conventional refrigerators
• 5% annual fuel consumption reduction on actual trucks
• Next-generation EJECS can be applied to CO2 heat
pump water heaters and car air-conditioners.
31

32. 5. Future Possibilities for EJECS
32

33. CO2 Emissions Reduction
All trucks in the market in Japan
Amount of CO2 emission [-] -8.1%
Small trucks
Small trucks
Middle trucks
Middle trucks
Large trucks
Large trucks
EJECS Expansion valve
refrigerators refrigerators
33

34. Future Applications
Ejector Technology
- Next generation ejector cycle system -
Water heater World first
World first
“Eco-Cute,”
using natural Room
Room
refrigerant CO2
air-conditioner
air-conditioner
Transport refrigerator
Ejector
Hot water
Hot water Stationary
Stationary
supply system
supply system Vehicle air conditioner air-conditioning
air-conditioning
system
system
Vehicle
Vehicle
34