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EP-4737724-A1 - A WORKING FLUID EXTRACTION SYSTEM FOR A DISPLACEMENT MACHINE AND A METHOD OF OPERATING THE SYSTEM

EP4737724A1EP 4737724 A1EP4737724 A1EP 4737724A1EP-4737724-A1

Abstract

A fluid separator system (340) for separating a condensable working fluid from a lubricant in a working fluid/lubricant mix. The fluid separator system (340) comprises: a fluid separator chamber (343); a fluid separator inlet (344); and a fluid separator shielding member (342) arranged at the fluid separator inlet (344) and configured to restrict a quantity of working fluid/lubricant mix entering the fluid separator inlet (344). The fluid separator chamber (343) is configured in use to provide a deceleration of fluid entering the fluid separator chamber (343) from the fluid separator inlet (344), such that, in use, the working fluid/lubricant mix entering the fluid separator chamber (343) is decelerated, thereby separating at least some of the working fluid from the lubricant.

Inventors

  • BJERKAN, Trond

Assignees

  • Heaten AS

Dates

Publication Date
20260506
Application Date
20221220

Claims (6)

  1. A fluid separator system (340) for separating a condensable working fluid from a lubricant in a working fluid/lubricant mix, the fluid separator system (340) comprising: a fluid separator chamber (343); a fluid separator inlet (344) configured to be operatively coupled to an internal volume (318) of a compressor (310); a fluid separator shielding member (342) arranged at the fluid separator inlet (344) and configured to restrict a quantity of working fluid/lubricant mix entering the fluid separator inlet (344) from the internal volume (318); wherein the fluid separator chamber (343) is configured in use to provide a deceleration of fluid entering the fluid separator chamber (343) from the fluid separator inlet (344), such that, in use, the working fluid/lubricant mix entering the fluid separator chamber (343) is decelerated, thereby separating at least some of the working fluid from the lubricant.
  2. The fluid separator system (340) of claim 1, wherein the fluid separator shielding member (342) is configured to restrict the quantity of working fluid/lubricant mix entering the fluid separator inlet (344) by limiting the amount of lubricant (381) droplets which are carried into the fluid separator chamber (343).
  3. The fluid separator system (340) of claim 1 or 2, further comprises a fluid separator channel (341) fluidly connected to the fluid separator chamber (343), such that in use separated working fluid can be evacuated from the fluid separator chamber (343) through the fluid separator channel (341).
  4. The fluid separator system (340) of claim 3, wherein the fluid separator channel (341) is fluidly connected to the internal volume (318) of the compressor (310).
  5. A method of separating a working fluid from a working fluid/lubricant mix the method comprising the steps of: a. providing a fluid separator system (340) according to any of claims 1 to 4; b. passing a working fluid/lubricant mix past the shielding member (342), thereby delivering a restricted quantity of working fluid/lubricant mix to the fluid separator inlet (344); c. passing the working fluid/lubricant mix through the fluid separator inlet (344) to the fluid separator chamber (343); d. decelerating the working fluid/lubricant mix in the working fluid chamber, thereby separating at least some of the working fluid from the working fluid / lubricant mix.
  6. The method of claim 5 when dependent on claim 3 or 4, further comprising a step of: e. evacuating separated working fluid from the fluid separator chamber (343) through the fluid separator channel (341).

Description

FIELD The present invention relates to systems of thermal machines having a condensable working fluid and methods of operating such systems. BACKGROUND Thermal machines such as heat pumps are known devices. Heat pumps are generally used to heat indoor spaces or supply hot water to a user. Use of heat pumps is desirable as they provide for more sustainable heat than heating devices which use fossil fuels. Heat pumps transfer thermal energy from a low-temperature heat source to a high-temperature heat sink. A refrigerant is used in the heat pump system. The refrigerant is a specially selected fluid which absorbs or rejects heat as it circulates through the heat pump system. A compressor in the form of a displacement device is used to pressurise the refrigerant and move the refrigerant through the system. An expansion valve is used as a controlling device which controls the balance between the operating pressures/temperatures and refrigerant/working fluid flow in combination with the compressor. The expansion valve provides a simple means for reducing the pressure, and hence the temperature, between the condenser section and the evaporator section of the heat pump, thereby completing the thermodynamic cycle, as will be easily understood by a person skilled in the art. Many industrial processes require heat at high temperatures in the form of, for example, steam or hot water, which is extremely energy-intensive to produce, especially when primary energy sources are used. Examples of industries utilising heat at high temperatures include paper, food and beverages, chemicals, automotive, metal, plastic, engineering, textiles and wood. For example, in the food and beverage industry, heat at high temperatures is used in processes such as drying, evaporation, pasteurisation, sterilisation, boiling, distillation, blanching, scalding, concentrating, tempering and smoking, to name merely a handful of examples. Industrial waste heat is usually not utilised due to the low temperature of such waste heat, which is lower than the temperature required in many industrial processes. This waste heat can be upgraded using a high-temperature thermal machine such as a high-temperature heat pump, and thus reused, which has clear economic and environmental benefits. Current high-temperature heat pumps face challenges with regard to the working fluid and with regard to maintaining the desired properties of the lubricant in the compressor. In screw, scroll and vane compressors, a substantial amount of lubricant is typically added to the working fluid to achieve good lubrication as well as good sealing between the flank of the screw/scroll/vane and the housing. When the temperature becomes high, for example >100°C, the lubricant will degrade more quickly and performance is greatly reduced, resulting in reduced run time, increased service costs and reduced service life. At even higher temperatures the lubricant may become completely degraded, and mechanical breakdown may even occur. Therefore, it is very important to maintain a good lubricant quality and integrity over the entire lifetime of the equipment. Reciprocating compressors are best equipped to operate at temperatures above 100°C due to their largely similar structure to internal combustion engines designed for operating temperatures typically up to 900°C in the working chamber and with lubricant temperatures up to about 100°C. Current industrial heat pumps can provide temperature lifts to around 160°C. At these temperature levels, the evaporator temperature is usually above 110°C, and there is a relatively high pressure and temperature in the compressor housing which affects the viscosity of the oil. Using a reciprocating compressor results in small amounts of working fluid blowby (working fluid leaking past the pistons) entering the internal volume filled with lubricant. The working fluid condenses and mixes with the lubricant, reducing the viscosity of the lubricant. A way to reduce the interference of working fluid in the lubricant is to heat the lubricant to a higher temperature to evaporate the working fluid therefrom. However, heating the lubricant also results in reduced viscosity and shorter service life. At least one aim of the invention is to obviate or at least mitigate one or more drawbacks of prior art. SUMMARY According to a first aspect of the invention, there is provided a working fluid extraction system for a displacement machine for removing a condensable working fluid from a working fluid/lubricant mix in an interior volume of the displacement machine separate from a working chamber of the displacement machine, the system comprising a condenser operatively connected to the interior volume, wherein the condenser is settable to a lower temperature than the temperature of the interior volume such that working fluid is drawn from the interior volume to the condenser in use, or is settable to a lower pressure than the pressure of the interior volume such that work