Eaton Makes Commercial Vehicle Air Conditioning More Efficient

• The next generation of its aluminum internal heat exchanger (IHX) improves the efficiency of the air conditioning circuits by ten percent.

• Eaton’s innovative pipe fittings technology with no pressure loss increase the efficiency of the circuits by another 3.5 percent.

Given this increase of efficiency of the air conditioning circuits, the same cooling performance can be achieved with a smaller climate compressor, reducing the vehicle’s weight. Both systems are suited for trucks as well as for construction and agricultural vehicles, and are also available for larger climate circuits such as for buses but will require adaptation to their larger pipe diameters.

The new IHX generation from Eaton – the Formed Inner Tube, or FIT – has optimized the flow mechanics of the inner pipe, reducing the amount of refrigerant required by more than 20g. This has a positive impact on potential environmental effects and saves costs, especially in large vehicle fleets. FIT is designed to handle traditional R134a and the new R1234yf.

Eaton’s innovative fittings technology eliminates sectional restrictions between pipe and hose to increase the energy efficiency of the air conditioning system. Both new systems were developed at the European Research Center in Rastatt and are manufactured in Baden-Baden, Germany.

Dr. Bert Leisenheimer, global engineering manager for Eaton’s Fluid Connectors Division, explained: “We see a great market potential in the commercial vehicle segment for our new internal heat exchanger FIT, as well as for our pipe fittings with no pressure loss. Applying both Eaton innovations jointly provides an efficiency improvement of up to 13.5 percent compared to a traditional mobile AC system. Assuming the same cooling performance, this can lead to a smaller climate compressor and support vehicle manufacturers in their goal of making trucks increasingly lighter with better fuel efficiency and fewer emissions.”

Next generation of the Internal Heat Exchanger

In 2007, Eaton launched its first-generation IHX (Coolaxial®), becoming the first manufacturer in Europe to offer the technology, which improves the efficiency of air conditioning circuits by ten percent. In the IHX, two air conditioning lines run in counter flow direction exchanging heat between one inner and one outer pipe. This way, the suction line conveying refrigerant towards the compressor cools even further the warm refrigerant coming from the condenser. This increases cooling efficiency, reduces CO2 emissions and fuel consumption and improves packaging.

This latest generation of FIT requires lower volumes to achieve the same degree of heat exchange compared with the previous generation and is more cost-effective as Eaton has optimized the flow mechanics of the inner pipe. Using a special production technique, a spiral is formed along the outer pipe that causes targeted turbulence in the refrigerant flow. This optimizes the exchange of heat and eliminates the need for an extrusion process to generate the geometry that increases the surface area of the pipe. The need for machining is also removed, along with its associated costs. Eaton also has reduced the part count and thus improved packaging density for the vehicle maker as the FIT no longer requires a special connector for attachment to the air conditioning system. Eaton’s FIT IHX is also available in steel with similar performance.

Fittings without pressure loss

The transition from pipe to hose components usually leads to sectional restrictions. In an air conditioning system, these restrictions reduce energy efficiency, particularly on the suction side when the refrigerant is upstream of the compressor. Eaton has developed an alternative fitting that widens the pipe and presses it onto the sleeve of the hose with an o-ring. Optimized for minimum pressure loss, this fitting eliminates sectional restriction and optimizes the energy consumption of the air conditioning system by up to 3.5 percent.