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Water drainage characteristics are dependent on the design of the evaporator: specifically the design of the fins and plates along with hydrophilic coating. A part of the hydrophilic coating washes off with the moisture that condenses over the evaporator core from the air-stream. Hence, water drainage characteristics of an evaporator changes with the vehicle mileage or the age of the vehicle. Since a part of the hydrophilic coating washes away, more water is retained within the evaporator at this condition. Hence, the effectiveness of the evaporator drainage deteriorates with the age of the vehicles. At this condition, the contact angle measured at the plate increases. Author has conducted an experimental study to measure the effectiveness of hydrophilic coating from evaporators taken out from arid (9 cores) and humid areas (16 cores) as a function of vehicle mileage or vehicle age. Contact angles and water retention were measured for a number of evaporators from different OEMs.

Water drainage characteristics of an evaporator changes with the age of the vehicle. This is due to the fact that with time, a part of the hydrophilic coating washes off with the moisture that condenses over the evaporator core from the air-stream. Hence, the effectiveness of the evaporator for water drainage deteriorates with the age of the vehicle. At this condition more water is retained in the evaporator as the contact angle increases. Author has conducted experiments with evaporators from multiple vehicles from different OEMs. These evaporators were analyzed to determine the effectiveness of the hydrophilic coating as a function of time or vehicle age. This is the first paper in the open literature that deals with the vehicle mileage or vehicle age with the evaporator plate contact angle and surface coating of an evaporator.

In this paper, the psychrometric analysis of the effect of laminate evaporator's tank position is presented. Essentially, water flyout characteristics, core surface temperature, and air resistance of a laminate evaporator is experimentally studied as a function of the tank position (either at top or at bottom) by maintaining the same operating test conditions. The tests were conducted when the blower speed was changed from low to medium; and low to high. For these tests, the system operated at low blower speed for an extended period of time before switching to either medium or high speeds. A four-pass laminate (plate type) evaporator with louvered fins with hydrophilic coating was used for this investigation. This study reveals that the tank position has a significant impact on the water flyout characteristics, evaporator core surface temperature, and air resistance.

In this paper, the results from an experimental investigation to determine the water carryover characteristics from the evaporator coil during transitional airflows is presented. The tests were conducted at the following transitional operating conditions: blower speed low to medium; and blower speed low to high. For both of these tests the system operated at low blower speed for an extended period of operation before switching to either medium or high speeds. A laminate (plate type) evaporator with louvered fins with hydrophilic coating was used for this investigation. Tests were also conducted with a screen at the downstream face of the core to prevent water carryover. This test was conducted for the worst case scenario, i.e., when the blower speed was increased to high from an extended period of operation at low speed.

In this paper a methodology is presented to predict the water drop trajectories at a given fan operating condition (i.e., face velocity), coil height and for a range of water drop diameters. Water drop carry over horizontal distances have been calculated as a function of evaporator coil height, water drop diameters, and face velocities for an evaporator unit. The simulated data has been compared with the experimental data. Initial results have shown that the model can predict the water drop trajectories fairly well. The developed model can be used to calculate the maximum horizontal distances the water drops will be carried over with the airstream for a range of water drop diameters. This is very important information to the design engineers for properly designing the evaporator units.