Test heat exchanger

Heat Flux Tests Removable tube test heat exchangers find an ideal use in the field for monitoring heat flux (corrosion) conditions, NACE TM0286-94 (similar to laboratory test. Fig. 28-4, page 28-12). 

Test heat exchangers can be fitted to side-stream circuits in process plant which simulate actual temperatures existing in the plant . Condenser tubes can be removed and corrosion assessed. 

Portable deposit/corrosion monitors are typically housed in an enclosure of perhaps 30 in. H x 20 in. W x 15 in. D. Components include inlet flow controller, strainer, adjustable electric heater, (outer) see-through glass housing, (inner) heated specimen tube or block, hot/cold temperature readout, corrosion rack, plus thermal overload, low-flow cut-off, and other safety devices. The specimen tubes or blocks are available in different metals (as are the corrosion coupons) and can usually be replaced in a matter of minutes. Unlike test heat exchangers, the cooling water in this type of monitor flows on the shell side of the specimen tube. 

All calculations are carried out at a window cut of 20%. This seems to be an optimum figure as it produces the maximum heat transfer coefficient at a given pressure drop for all tested heat exchangers. It is further assumed that TEMA standard clearances would exist between the tubes and baffles and between the shell inside diameter and baffle outside diameter. The various numbers in Figures 2-33a and b denote the fluids, pressure drops and exchanger dimensions given in Table 2-6. 

Answer by author Yes, we tested heat exchangers with many different designs, including pin fins, coiled fins, tubes coiled in spirals, etc. It is our opinion that the present helically finned and coiled exchanger design is the most useful design for the small compact exchangers. 

A better method of replicating the hydrodynamics and thermal conditions of critical operating equipment is a test heat exchanger, using a small side stream of water from the coohng tower water circuit. This technique is more complex and expensive as a result, it has been used less extensively than the techniques described previously. In a test heat exchanger, water flow and heat flux can be controlled. If... 

In order to obtain reliable results from a test heat exchanger, the above factors must be determined from the plant exchanger in the system that is to be duplicated. Once the plant parameters have been determined, they should be duplicated as nearly as possible in the test unit and held constant. Figure 7 is a schematic of a typical two-tube test heat exchanger. It is used to simulate tube side water conditions in a plant exchanger. Heated water or steam on the shell side is used to heat the tubes. 

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