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Technical Paper

Double-pipe Internal Heat Exchanger for Efficiency Improvement in Front Automotive Air Conditioning System

2007-04-16
2007-01-1523
In automotive air conditioning, balancing comfort and fuel efficiency is very important. Vehicle cooling performance improvements during initial cool down has reached a limit in recent years, especially in very hot regions. We have addressed this issue by developing a unique double-pipe internal heat exchanger. In the main discourse, we first clarify the concept of the internal heat exchanger system (IHE) using the temperature difference between the high and low pressure pipes in the refrigeration cycle, and propose the application of an efficient internal heat exchanger. This unique double-pipe internal heat exchanger can easily be manufactured by inserting the inner pipe into the outer pipe and by fixing the pipes at both ends. The length of the IHE is 400mm. This double-pipe internal heat exchanger can increase cooling performance by 5-12% at the equivalent power consumption levels in the same space as a conventional front air conditioner system.
Technical Paper

Improvement in the Brazeability of Aluminum Clad Thinner Fin for Automotive Heat Exchanger

2005-04-11
2005-01-1390
Through the years, aluminum automotive heat exchangers have been developed in order to have a high performance and a light weight. Therefore, the thickness of the aluminum sheets for the application has been reduced. As the brazeability declines with the reduction in thickness, fins having a thickness under 80μm may be difficult to secure a good brazeability. Therefore, we studied the brazeability to determine the limit of thickness using clad fins from 40 to 80μm. The fillet volume formed at the joints of the fin and tube decreased with the decreasing fin thickness and the Si content in both the filler metals and the core alloys. The suitable range of Si content in the filler metals and the core alloys to obtain a good brazeability decreased with the decreasing fin thickness. When the fins were thinner than the critical values, it was impossible to have a good brazeability.
Technical Paper

The Development of the Lead Free Carbon Brush for Starters

2005-04-11
2005-01-0599
Carbon brushes for automotive starters are used under severe conditions of high electric current density, high contact pressure and high sliding velocity. Therefore lead has traditionally been added to brushes to improve performance and durability. Lead is an environmental hazardous substance. In the EU, the law prohibits adding lead to brushes for electric motors which is installed on new automobiles in and after January 2005. In order to develop the lead free carbon brush for starters, we analyzed the effect and selected substitutive substance of lead. Adding lead to the brush reduces the electric resistance increase of the brush in high-temperature and high-humidity atmosphere and in high-temperature atmosphere. Furthermore lead reduces the wear amount of brush. We developed the lead free brush surpassing the lead addition brush in performance and durability by addition of lead alternatives silver and zinc.
Technical Paper

Application of Nylon Composite Recycle Technology to Automotive Parts

2003-03-03
2003-01-0794
Recently there has been a market trend requiring End of Life Vehicles to be recycled to satisfy current legislation; therefore, we are approaching the recyclability of automotive parts based upon these environmental requirements. At this time, we have demonstrated a new recycle technology for polyamide using one of the largest automotive applications, the radiator end tank which has been previously viewed as degraded material due to hydrolysis and deemed as shredder residue. This technology [1] allows for the recovery of the base resin that is then recycled into a radiator end tank with performance equivalent to one made of virgin resin. The process for this technology includes collection of post consumer radiator end tanks that are then reground, dissolved, filtered for glass fiber removal, precipitated, recovered, and compounded into a usable resin. This technology is referred to as “Nylon Composite Recycle”.
Technical Paper

Development of Quad-layer Clad Brazing Sheet for Drawn Cup Type Evaporator: Part 2

2001-03-05
2001-01-1254
We have achieved significant weight reduction for the MS (Multi-Tank Super Slim Structure) Evaporator (1)currently in production at DENSO CORPORATION. The evaporator of HVAC unit, located in the instrument panel, is a component of the aluminum heat exchanger used in automotive air conditioners. The new evaporator uses thinner quad-layer sheet material, thanks to optimization of the electrical potential among its outer filler metal, intermediate anodic layer and core. The evaporator is thus lighter than conventional evaporators, but retains equivalent corrosion resistance.
Technical Paper

Development of Quad-layer Clad Brazing Sheet for Drawn Cup Type Evaporators: Part 1

2001-03-05
2001-01-1253
Having a light weight, a good heat conductivity and a good brazability, aluminum alloy is widely used for automotive heat exchanger systems. The major problem with Aluminum is perforation of the tube by pitting corrosion and corrosion protection is necessary in the field. In radiator and condenser systems using the the Nocolok brazing process given good corrosion resistance using cathodic protection with sacrificial anode made of Zn-sprayed onto tube or low corrosion potential fins etc. On the other hand, in drawn-cup type evaporators, that are fabricated from brazing sheet tubes in vacuum brazing method and then covered low electro-conductive drain water film in operation, the effect of cathodic protection by the anode fin is limited to a very small area. Therefore, this has been studied to improve self-corrosion resistance of the core in the brazing sheet tube.
Technical Paper

Development of a Cooling Module Containing a Radiator and a Condenser Part 1: Product Design

2001-03-05
2001-01-1018
In conventional automobile designs, a radiator for cooling the engine and a condenser for condensing the air-conditioner refrigerant are typically configured independently of each other; they are usually mounted in series in the front of the engine compartment so that they will receive sufficient air flow while the vehicle is running. We have developed a smaller and higher performance cooling module by integrating these two heat exchangers into one unit. (Fig 1) For the heat dissipation fin, we have employed an integral fin construction equipped with an insulating slit, resulting in effective prevention of thermal conduction from the higher temperature radiator side, to the condenser side. We also succeeded in improving heat dissipation performance by making effective use of the connection part of the integral fin.
Technical Paper

Development of a Cooling Module Containing a Radiator and a Condenser - Part 2: Alloy Development

2001-03-05
2001-01-1019
In conventional automobile designs, a radiator and a condenser are typically configured and mounted independently of each other. We have developed a smaller and more powerful cooling module by integrating these two products into one piece. The new cooling module has been designed to share the fin material and to have an insulating slit and other means for effective prevention of heat loss that occurs due to thermal conduction between the radiator and the condenser1). In addition, as one of the key techniques for integrating fins, we studied thermal spraying of brazing filler to the tube material and were able to achieve a practical-level cooling module through use of high-performance fins, contributing largely to the efforts to create a more compact, higher performance cooling module.
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