Chiller bypass

#There are a number of industrial processes that require a supply of chilled water or other liquid coolant that maintains the industrial process within predetermined thermal limits. The water chiller is often a stand-alone device, complete in and of itself, with appropriate supply and return connections for conduits connected to the industrial process. The industrial process may be an injection molding machine for molding plastic devices; a number of other industrial processes have similar requirements. As with any industrial equipment, cost may be an important factor for the chiller.

#In recent years, particularly with thee advent of electrical discharge machining (EDM) equipment, it has been necessary to provide de-ionized water as the liquid coolant. The usual electrical conductivity of water that is not thoroughly de-ionized cannot be tolerated. Conventional metal fittings are undesirable because continued use of fittings of this kind, in the chiller, may lead to degradation of the initially de-ionized water to the extent that ineffective operation may result. As a consequence, the bypass conduit in the chiller has frequently been made of stainless steel. There is usually a valve in the bypass line; the result is that the complete bypass, which is a necessity in order to avoid freeze-up and/or overheating of the chilling apparatus, and to avoid pump damage, becomes unduly expensive. This is particularly true in instances in which the bypass and other internal coolant circuits in the chiller are formed of stainless steel.

#It is a principal object of the present invention, therefore, to provide an improvement in a liquid coolant chiller, particularly for industrial processing, that minimizes the use of stainless steel in the chiller and that has no valve in the bypass line of the chiller.

#FIG. 1 is a schematic diagram of a water chiller connected to an industrial process, the water chiller incorporating the improvement of the present invention;

#FIG. 2 is an exploded view of principal components for the bypass line connections in the water chiller of FIG. 1;

#FIG. 3 is a detailed view, on an enlarged scale, of that portion of FIG. 2 enclosed within the circle 3; and

#FIG. 1 illustrates a water chiller 10 or other like chiller for a liquid coolant; chiller 10 incorporates the improvement of the present invention. Chiller 10 includes a liquid coolant reservoir 12. In most instances, the liquid coolant is water and frequently is de-ionized water for use in EDM equipment, in lasers, and in other industrial processes in which the coolant must be non-conductive and/or very clean. Chiller 10 further includes an evaporator 13 having an inlet 14 connected by a conduit 16 to the outlet 15 of tank 12. A pump 18 is interposed in series in conduit 16. The outlet 17 of evaporator 13 is connected to a supply line 19 having a connection 20 that is connectable to a further conduit 21 extending to an industrial process apparatus 11. The industrial process apparatus 11 may comprise EDM equipment, laser apparatus, or an injection molding machine. Alternatively, apparatus 11 could include any industrial processing apparatus that requires a supply of chilled water, particularly de-ionized water, or some other liquid coolant. Evaporator 13 is connected, as by refrigerant lines 41 and 42, to a refrigerating apparatus 40 that may include a condenser and a compressor. A control 39 is provided for refrigerating apparatus 40.

#There is a coolant return line 22 from process apparatus 11 to a connection 23 that is a part of chiller 10. Within chiller 10, a coolant return line 24 extends from connection 23 to the inlet 25 of reservoir 12, thus completing the coolant loop. No pump has been shown in the return line 22-24. It will be appreciated that there may be a pump in industrial process apparatus 11 or, in some instances, there may be no need for a further pump. The pressure of the liquid flowing in return line 24 is usually below the supply pressure in line 19. In some systems the return line pressure may be near or at atmospheric pressure.

#There is a first fitting 31, a special tee having four ports, incorporated in series in the coolant supply line 19 of chiller 10. Fitting 31 is connected by a bypass line 33 to a second special tee fitting 32 that is incorporated in series in return line 24 in chiller 10. An orifice member 34 is included in series with bypass line 33; it is shown as being mounted in fitting 32. There is an additional conduit 38 in chiller 10 that connects fitting 31 to a thermal sensor 37. Sensor 37 is electrically connected to the control 39 for refrigerating apparatus 40, which is usually a microprocessor control. A tee fitting 35 may be incorporated in series in line 38 to connect that line to a pressure gauge 36.