Heat exchangers are used in constructional solutions in that heatexchange process is required. Construction of a heat exchanger is crucial for its effectiveness. The heat exchanger in a personal car is mounted before the radiator in front of the car. Heat from a refrigerant is transferred through walls of flat tubing with microchannels to fins and then to ambient air. Condenser is responsible for removing heat from gaseous refrigerant under high pressure and at high temperature. By removing heat, the refrigerant becomes liquid (Fig. 1). Volume of emitted exhaust gas is significantly influenced by load of the engine that drives the air-conditioning compressor and thus by amount of the refrigerant used in the air-conditioning system. The Montreal and Kyoto Protocols enforce also use of smaller amounts of refrigerants with high Global Warming Potential index (GWP for R134a = 1430). For this reason, condensers become much more efficient than they were a dozen years ago. Currently, automotive A/C systems use mainly high-performance multiflow subcool condensers (Fig. 2). Construction of a condenser is based on aluminium flat tubing with microchannels. A system of lamellae is arranged between microchannels, creating a network of tiny channels for air flow. The lamellae are brazed under controlled atmosphere (CAB technology) to flat condenser tubes (Fig. 3). This type of joints used in place of mechanical joints are popular not only with regard to lower production costs, but also to better meeting the requirements of safety and recycling . Lamellae are usually made of an alloy series 3000, most often the grades 3003, 3103 and 3203. For brazing, alloys series 4000 are used, mainly the grades 4343, 4145, 4047 and 4045 [1÷4]. In the case of this solution, there is no risk of galvanic corrosion that occurs in shell-and-tube structures. However, this does not mean that they are completely free from corrosion risk. The issues related to[...]
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