Refrigerant dryer

Abstract

A refrigerant dryer, in particular a compressed air refrigerant dryer, is provided for drying a gaseous fluid while cooling the gaseous fluid using a refrigerant. The dryer includes a pressure fluid-refrigerant agent-heat exchanger (30) in which a cooling of the gaseous fluid takes place directly or indirectly by a refrigerant conveyed in a primary loop (16), one or more refrigerant compressor / compressors (24) for operating the primary loop, and a cold accumulator (13) with an accumulator-side heat exchanger (20) which couples an accumulator discharge fluid to a cold accumulator medium (14). The pressure fluid-refrigerant agent-heat exchanger (30) and the cold accumulator (13) are fluidically connected or can be brought into fluidic connection via a discharge loop (15) for an accumulator discharge fluid. The cold accumulator (13) is arranged, relative to gravity, above the pressure fluid-refrigerant agent-heat exchanger (30), in such a manner that the heated accumulator discharge fluid is conveyed through the discharge loop (15) for cooling in the cold accumulator (13), is cooled there, and subsequently re-conveyed to the pressure fluid-refrigerant agent-heat exchanger (30).

Description

BACKGROUND OF THE INVENTION [0001] The invention relates to a refrigerant dryer, in particular a compressed air refrigerant dryer for drying a gaseous fluid while cooling the gaseous fluid using a refrigerant. The invention also elates to a method for cooling a gaseous fluid in a refrigerant dryer, in particular a compressed air refrigerant dryer. [0002] Refrigerant dryers are known per se. Reference is made to the document European patent application publication EP 1 434 023 A2 as merely one example. By the term cold drying, a method known per se is understood in general as well as according to the present invention, in which the condensable components are removed from a flow of gas by cooling the gas flow below the respective pressure dew point. The term “pressure dew point” is correspondingly understood as the temperature to which the gaseous fluid can be cooled without liquid condensing out. Cold dryers are used in particular for drying compressed air by cooling the compressed a...

AI Technical Summary

Benefits of technology

[0016] Compared to the above, the object of the present invention comprises providing a refrigerant dryer and a method of cold-drying a gaseous fluid in a refrigerant dryer in which a higher energy efficiency, therefore a more favorable relationship of the energy used, in particular electric energy, is achieved in relation to the amount of dried pressure fluid.

[0021] In this respect, it is proposed according to the invention to provide an accumulator discharge fluid or general refrigerant in a refrigerant dryer, and in a method of cold-drying a gaseous fluid respectively, which enables cold transfer from a cold accumulator which may also be spatially distant therefrom, if needed. This results in essentially higher freedom with respect to the configuration and dimensioning of the cold accumulator and the selection of a suitable cold accumulator medium. By the herein proposed refrigerant dryer, the herein proposed method respectively, the energy efficiency can moreover be decisively enhanced, in particular in part load or zero load situations.

[0031] In a specific embodiment, heat is extracted in a charge state from the cold accumulator by an accumulator-side heat exchanger or a separate loading heat exchanger by an accumulator charging fluid, which may be identical to or separate from the accumulator discharge fluid. In the charge state, the cold accumulator is in active communication with the refrigerant of the primary loop through the accumulator-side heat exchanger and / or a separate loading heat exchanger for cooling the cold accumulator medium, respectively reducing the heat content of the cold accumulator medium.

[0035] In a further possible embodiment, the means for increasing the thermal conductivity in the cold accumulator are formed in that substances, particles or fibers having high thermal conductivity are incorporated into the cold accumulator medium for improving the effective thermal conductivity in the cold accumulator medium.

[0038] In a particularly preferred embodiment of the present invention, the flow paths of the discharge loop are partially or exclusively used for reducing the heat content of the cold accumulator by the refrigerant of the primary loop.

Problems solved by technology

It is, however, problematic to provide an energy-efficient control of the cooling capacity of a refrigerant dryer, since this control has to be effected in adaptation to variable pressure fluid volume flows, pressure fluid moistures and / or pressure fluid temperatures.

While the hot gas bypass control has a relatively poor energy efficiency, it is the limited range of control for the speed control which is problematic in most cases.

An ON / OFF control in an expedient structural implementation is highly efficient but problematical with respect to maintaining a constant temperature of the pressure fluid at the condensate separator inflow.

In order to keep this undesired temperature hysteresis as low as possible, despite limited refrigerant compressor operating cycles, large capacities of the cold accumulator are necessary at simultaneously good heat transfers (i.e., low temperature differences) between the evaporating refrigerant agent, the thermal accumulator mass within the cold accumulator and the pressure fluid flow, which poses structurally contradictory requirements and hence is problematic.

In addition, large temperature differences during heat transfer are basically disadvantageous to the energy efficiency since they are associated with a high “energy production.”

In combination with the likewise required large capacity of the cold accumulator, this poses problems as to the structural space and arrangement of the components and heat exchanger surfaces.

The problem hence includes finding a structural configuration by which large efficient heat exchanger surfaces, short heat conduction paths having a high thermal conduction coefficient, and large or voluminous cold accumulators may be obtained simultaneously with a small structural space and expenditure.

The larger these prior art cold dryers have to be dimensioned, the less favorable the cost structure becomes as a result of the necessarily large and expensive heat exchangers, which moreover require expensive raw materials such as copper and aluminum.

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