 In this module, we will talk about the design of continuous sterilization process for the medium sterilization. So, the most suitable as we seen and discussed in our previous module that there are two system or a two approaches of continuous medium sterilization, one is indirect method and other one is the direct method. As concerned, the most suitable indirect method is the indirect heat exchangers. As concerned, the indirect heat exchangers are the double spiral type which consist of two sheets of high grade stainless steel which have been curved around a central axis. You can see here, this is the central axis and these are the different coils around that. The end of the spiral are sealed by the covers. So, these you can see that these are the both covers. To achieve the sterilization temperature steam is passed through one spiral and the medium through the other in the counter current steam. So, if the steam is entering by this way and then the medium is by this way. So, the spiral heat exchangers are also used to cool the medium after passing through the cooling, through the holding coil. So, the incoming unsterile medium is used as the cooling agent in first cooler. So, that the incoming medium is partially heated before it reach to the sterilizer and thus heat is conserved. So, this major advantages of the spiral heat exchangers are the first one is the two streams of the medium and the cooling liquid or medium and the steam are separated because both are because it is the indirect method. So, both remain separated. So, these will be separated by a steel barrier with the gasket seals being confined to the joints with the end plates. So, this makes the cross contamination between the two streams unlikely. As concerned the spiral route transverse by the medium allows the sufficient clearance to be incorporated for the system to cope with the suspended solids. The exchangers tend to be self-cleaning which reduce the risk of sedimentations falling and burning on because when there is a steam on a one spiral on other hand the space between that the medium is passing then what happen when the heat will be and the desired temperature at that temperature there will be a smaller sedimentation. So, due to the red sedimentation that can blockage of that spiral. So, these are some limitation when we talk about this indirect method of continuous sterilization process.