TUBE & SHELL HEAT EXCHANGERS
Davtec Tube and Shell heat exchangers are designed to efficiently transfer heat from one matter to another. When a fluid is used to transfer heat , the fluid could be a liquid such as water or oil as well as a range of different mediums. Heat exchangers are used in both heating and cooling applications. The Tube and shell heat exchanger has widespread applications across a large cross section of industry.
Hydraulic systems can use either of two methods of load control: the energy-loss method, in which flow to the actuator is set by valving, or the volume-control method, in which the stroke of a variable-displacement pump sets the rate at which fluid flows to the actuator. Although systems using variable-displacement pumps inherently are more efficient, they are more costly and cannot react as quickly as systems using servo or proportional valves operating from a constant pressure source.
Most industrial hydraulic systems are designed using the energy loss method. Such systems cost less to build and are more responsive because system energy is immediately available. But because of the inherent poor efficiency of these systems, energy lost as heat can exceed that of the mechanical power produced by the system. For example, even well-designed electrohydraulic servovalve or proportional valve systems may convert 60% to 80% of input horsepower to heat. Well-designed non-servo systems can produce heat losses of only 20% to 30%.
Some Hydraulic system heat is desirable to bring fluid up to operating temperature. Cold hydraulic oil has a higher viscosity than warm oil. So maintaining an operating temperature of 100° F would cause sluggish operation and excessive pressure drop in a system designed to operate at 140° F. When a system begins operation on a cold winter morning, for example, the oil should be allowed to warm until it reaches a temperature where heat is generated at the same rate as system heat radiating into the atmosphere or other cooling medium.
If heat generation exceeds the radiation rate, the excess heat can cook the oil, start oil decomposition, form varnish on system component surfaces, and begin to deteriorate system seals. Excess heat sooner or later spells trouble for any Hydraulic system. Too much heat breaks down oil, damages seals and bearings, and increases wear on pumps and other components. The solution to these problems is the inclusion of a properly sized heat exchanger as a component of the system.