Figure 5 illustrates the adiabatic properties of a real heat exchanger. This is also often done using a plate heat exchanger. This resulted in Airworthiness Directives mandating the replacement of the heat exchanger. Customers have the option of purchasing their mainframe with a water-cooled heat exchanger. In modern breweries this is achieved through a plate heat exchanger. Many metal collectors are installed as part of a sealed heat exchanger system. Baffles are an integral part of the shell and tube heat exchanger design. The cooling air is recirculated through a heat exchanger. The fouling rate also depends on the material used to construct the heat exchanger. The resulting liquid-gas mixture is preheated by flowing through a heat exchanger. The blue solid line shows the heat flowing out of the cooler heat exchanger. Engine bleed air is admitted through a flow control valve to a heat exchanger. Another type of regenerator is called a micro scale regenerative heat exchanger. Another type of heat exchanger is the plate heat exchanger. Another limitation is the temperature difference across the heat exchanger.