Mitsubishi Heavy Industries Technical Review Vol. 51 No. 2 (June 2014)
41

TEJ35A Electric Transport Refrigeration Unit
Using Inverter for Light Trucks

Tr a n s p o r ta t i o n R e f r i g e r a t i o n D e pa r t m e n t
Air-Conditioning & Refrigeration Division
M a c h i n e r y, E q u i p m e n t & I n f r a s t r u c t u r e

In recent years, automotive manufacturers have launched HEV and EV light truck models
with a secondary battery similar to passenger vehicle models, and the improvement ofenvironmental performance has been progressing in combination with the electric equipment
mounted on the truck. Mitsubishi Heavy Industries, Ltd. (MHI) has developed the TEJ35A
inverter-driven electric transport refrigeration unit that operates with power fed from a secondary
battery to attain a higher temperature stability and higher environmental performance. This paper
presents the TEJ35A.

|1. Product summary
Transportation refrigeration units are required to have sufficient cooling capacity for rapid
cooling to the set temperature, temperature controllability for maintaining the temperature after theattainment of the set temperature, and energy saving characteristics.
The developed TEJ35A has achieved cooling down capability (cooling down speed),accuracy of temperature retention, and energy saving characteristics on a high level due to theemployment of inverter-based variable speed control, which operates according to heat loadconditions, for the DC twin rotary compressor proven in MHI’s air conditioning systems.

|2. Advantages of the product2.1

High temperature stability

The TEJ35A is operated using power from a secondary battery and therefore can deliver
stable cooling capacity regardless of the operating conditions of the vehicle. This enables
constant-temperature transportation even under conditions where the vehicle is stopping with the“idling stop” function turned on, stuck in traffic congestion, or waiting for traffic signals to change(Figure 1).

Figure 1

Cooling capacity during transportation

In addition, the TEJ35A enables compartment temperature stability with high accuracy byraising the compressor speed just after the start of cooling so that the temperature can reach the setvalue in a short period of time, and finely controlling the compressor speed according to thecompartment temperature after the attainment of the set temperature (Figure 2).

Mitsubishi Heavy Industries Technical Review Vol. 51 No. 2 (June 2014)42

Figure 2 Cooling speed and compartment
temperature stability

2.2

Maintenance saving

The TEJ35A eliminates components that need to be replaced such as drive belts andrefrigerant hoses that are used in MHI’s existing models to enable a considerable reduction of themaintenance cost. This results in the elimination of the need for down time of the vehicle formaintenance, and hence a significant reduction in the time the vehicle is out of service because ofmaintenance (opportunity loss).

2.3

High environmental performance

The TEJ35A uses R410A refrigerant, which has a lower GWP (Global Warming Potential)
than the R404A used in existing models, resulting in GWP being lowered by 47% from 3920 to2090 and thus a reduction of global warming effect by half.
In addition, the compressor is controlled to the optimum speed at which the operating
efficiency is enhanced according to the compartment temperature and the operating pressure. This
enables the improvement of annual operating efficiency by 15% and a reduction of annual CO2
emissions by 15% compared with MHI’s conventional models that are driven by the engine of thevehicle.

2.4

Flexibility in mounting on vehicle

The TEJ35A is designed so that it has compatibility with MHI’s conventional models inmounting, allowing for high mounting flexibility.
In addition, the TEJ35A can be power-fed from a 250 to 400 VDC power source, which
covers all secondary batteries used for Japanese HEV and EV, making it flexible in terms of powersource. When the supply voltage falls, the TEJ35A uses MHI’s unique inverter-based motor
control technologies such as field weakening control and overmodulation PWM (Pulse WidthModulation) control to stabilize the motor speed and refrigeration capability is maintained over avoltage variation.

|3. Specifications and structure
Table 1 and Figure 3 show the specifications and structure of the TEJ35A, respectively.
Table 1Specifications of TEJ35A

Model type
TEJ35A
Compartment°C-30 to +30
temperature
Operating temperature
range
Ambient°C-20 to +40
temperature
Cooling capacity(Ambient temperature 35°C/W
1400 to 4300 (*)
Compartment temperature 0°C)
VDC250 to 400
High voltage DC power Voltage
sourcePowerW
Max. 3600 (at 360 VDC)
Voltage
VDC
13.5 or 27.0
Low voltage DC powersourcePowerW
Max. 490
External dimensions
Main bodymm
W1780 x H785 x D570 (Outside 470, Inside 100)
Weightkg
97
Main bodykg
92.5
Accessorykg
4.5
Refrigerantkg
R410A, 1.7
NoisedB(A)60/7.5 m* The maximum cooling capacity varies depending on the electric power received.

Mitsubishi Heavy Industries Technical Review Vol. 51 No. 2 (June 2014)43

Figure 3

Structure of TEJ35A|4. Future prospects
In the future, MHI will continuously contribute to the quality improvement of constanttemperature transportation items and the establishment of a low carbon society through efforts on
improving the performance of electric transport refrigeration units reflecting the opinions ofcustomers and the expansion of our product line-up in response to market needs.