DE102021000460A1 - Power increase refrigeration machine - Google Patents

Abstract

The invention, according to the preamble of claim 1, for improving the performance of compressor refrigeration machines, relates to a modification of the refrigeration cycle of a refrigeration machine (Figure 1). The modification is carried out by integrating a small coaxial heat exchanger (6) (Figure 2), which uses the high temperature of the gaseous refrigerant compressed by the compressor (1) to convert the now liquid refrigerant after the condenser (2) bring to a higher temperature and pressure level immediately before the throttle (4). The expansion of the gaseous refrigerant in the throttle (4) causes a drop in temperature, which causes the refrigeration capacity that is emitted, for example, in a refrigerator via the evaporator in the cold room. The cold gaseous refrigerant from the evaporator (5) is sucked in by the compressor and compressed again. Commercially available highly volatile hydrocarbons with a low boiling point, such as isobutane (R600A), are used today as refrigerants, which, unlike the refrigerants used in the past, are not harmful to the climate. Other refrigerants with a similar effect are also used in or as a medium in refrigeration machines/heat pumps.

Description

The invention, according to the preamble of patent claim 1 for increasing the performance of refrigeration machines, relates to intervention in the refrigeration circuit of refrigeration machines according to the prior art ( 1 ). Refrigeration machines with compressors, designed as piston compressors or rotary compressors, are based on the principle of the heat pump. According to the invention, an additional heat exchanger (6) ( 2 ) integrated into the refrigerant circuit of a chiller. Areas of application are: Household appliances, such as refrigerators, chest freezers, freezers, chest freezers, fridge-freezers, heat pump dryers, heaters and in industrial areas, such as temperature/climate chambers, cold stores, environmental test systems. The field of application of refrigeration machines extends, can be both stationary and mobile (vehicles, ships, aircraft).

The essential feature of the invention is the use of the heat of compression of the refrigerant immediately after the compressed refrigerant has exited the compressor (1) to reheat the refrigerant circuit immediately before the throttle (5). A heat exchanger (6) is integrated into the circuit for this reheating. An expansion valve or a capillary is usually used as the throttle (5). The capillary is preferably used in household appliances. The reheating of the refrigerant in the coolant circuit by a few degrees of temperature also causes an increase in pressure. This increases the performance of the cooling circuit due to the associated higher potential difference before and after the throttle. In addition, the heat exchanger (6), with its integration into the cooling circuit before the condenser, also promotes the liquefaction process of the refrigerant.

1. a) Temperatur - Druck Kühlmittel, unmittelbar nach dem Kompressor: ta = 70 °C; pa = 20 bar
2. b) Temperatur - Druck Kühlmittel, ohne Leistungsverstärkung durch den Wärmetauscher (6) nach dem Verflüssiger (3), vor der Drossel (5): tv = 40 °C; pv = 10 bar.
3. c) Temperatur - Druck Kühlmittel mit Leistungsverstärker durch den Wärmetauscher (6) nach dem Verflüssiger (3) und Wärmetauscher (6), vor der Drossel (5): tvl = 50 °C; pv1 = 12 bar.*

* diese Werte sind in diesem Beispiel nicht exakt berechnet. Die erzielbaren Werte sind auch von der Auslegung des Wärmetauschers abhängig. Durch Berechnungen und Auslegungsversuche kann der Wärmetauscher und damit der Prozess anwendungsspezifisch optimiert werden.Example: $$\text{T}1/\text{p}1=\text{T}2/\text{p}2;\text{T}1\text{or}.\text{<figure-callout id="2" label="T" filenames="DE102021000460A1\_0002.png,DE102021000460A1\_0003.png" state="{{state}}">T</figure-callout>}2=\text{T}+\text{t}\left(°\text{K}\right)$$

1. a) Temperature - pressure coolant, immediately after the compressor: ta = 70 °C; pa = 20 bar
2. b) temperature - pressure coolant, without power boost by the heat exchanger (6) after the condenser (3), before the throttle (5): tv = 40 °C; PV = 10 bars.
3. c) Temperature - pressure coolant with power booster through the heat exchanger (6) after the condenser (3) and heat exchanger (6), before the throttle (5): tvl = 50 °C; pv1 = 12 bar.*

* these values are not exactly calculated in this example. The achievable values also depend on the design of the heat exchanger. The heat exchanger and thus the process can be optimized for specific applications by means of calculations and design tests.

The delta of e.g. +10 °C and + 2 bar (here as an example: c minus b = delta) improves the cooling capacity or reduces the power consumption with the same cooling capacity of the device, in the range of approx. 20% to 30%.

Designations for Figure 1 and Figure 2:

• 1

  1

  Verdichter (z.B. Kolben- oder Rotationsverdichter)

  2

  Verflüssiger (z.B. Rückwand Kühlschrank)

  3

  Trockner/Filter (entweder nur Trockner oder Kombination Filter-Trockner)

  4

  Drossel (Expansionsventil oder Kapillare)

  5

  Verdampfer (innen im Kühlschrank)

  6

  Wärmetauscher z.B. koaxialer WT, Röhren-WT, Platten-WT)

  7

  Füll-/Entleerventil

  ta →

  Temperatur Austritt Verdichter (1)

  pv →

  Druck Austritt Verdichter (1)

  tv →

  Temperatur nach Verflüssiger (2)

  pv →

  Druck nach Verflüssiger (2)

  tv1 →

  Temperatur nach Wärmetauscher (6)

  pv1 →

  Druck nach Wärmetauscher (6)

refrigeration cycle

• 1

  1

  Compressors (e.g. piston or rotary compressors)

  2

  Condenser (e.g. rear wall of refrigerator)

  3

  Dryer/Filter (either only dryer or combination filter-dryer)

  4

  Throttle (expansion valve or capillary)

  5

  evaporator (inside the refrigerator)

  6

  Heat exchanger e.g. coaxial WT, tube WT, plate WT)

  7

  Fill/drain valve

  ta →

  Compressor outlet temperature (1)

  pv →

  Compressor outlet pressure (1)

  tv →

  Temperature after condenser (2)

  pv →

  Pressure after condenser (2)

  tv1 →

  Temperature after heat exchanger (6)

  pv1 →

  Pressure after heat exchanger (6)

• 2 Nicht maßstäblich! Abmessungen in mm ca. 4-5 Windungen; Höhe 50 mm - 80 mm da = Außendurchmesser: ≥ 50 mm - ≤ 100 mm Anschlüsse an Kühlkreislauf mittels Kupferfittinge Anschlüsse inneres Rohr ca. d: 6 mm Anschlüsse äußeres Rohr ca. d: 6 mm Koaxiale Rohre des Wärmetauschers:
  • -inneres Rohr: - Durchströmung = gasförmig; Anschluss Verdichter - äußeres Rohr: - Durchströmung = flüssig: Anschluss nach Verflüssiger
  Durchströmungs-Richtung: Gegenstromprinzip oder Gleichstromprinzip

Coaxial Heat Exchanger

• 2 Not to scale! dimensions in mm approx. 4-5 turns; Height 50 mm - 80 mm da = outer diameter: ≥ 50 mm - ≤ 100 mm Connections to the cooling circuit using copper fittings Connections to the inner pipe approx. d: 6 mm Connections to the outer pipe approx. d: 6 mm Coaxial pipes of the heat exchanger:
  • -inner tube: - flow through = gaseous; Compressor connection - outer pipe: - flow = liquid: connection after condenser
  Direction of flow: counter-current principle or co-current principle

Claims (5)

The refrigerant cycle of chillers ( 1 ) with compressor (1), condenser (2), dryer / filter (3), throttle (4) - designed as an expansion valve or capillary - and evaporator (5) according to the prior art is modified to increase performance so that the refrigeration machine either Less current is required at the same voltage with the same cooling capacity, or an improvement in the cooling capacity is achieved with constant current consumption, usually controlled by a temperature or power controller. The cooling machine according to the invention is characterized in that the pipeline of the refrigerant circuit, immediately after the compressor (1), is modified in such a way that the high heat of the compressed, gaseous refrigerant is used by the inventive integration of a coaxial heat exchanger (6) to Heat is transferred to the refrigerant in the condenser (2), which has now become liquid and cooler, immediately before the dryer/filter (3) and/or the throttle (4), thereby increasing the temperature of the liquid refrigerant. With the increase in temperature, there is also an increase in pressure in the closed refrigerant circuit. The heat exchanger (6) after claim 1 designed as a plate heat exchanger or coaxial tubular heat exchanger - coiled (Figs. 1-2) or straight (Fig. 3). The heat exchanger preferably works on the countercurrent principle. To avoid heat loss to the environment, the heat exchanger is thermally insulated. that the heat exchanger (6), after claim 1 , also as a spiral jacket of the refrigerant line or the dryer/filter (3), to increase the contact surface in the cocurrent principle or in the counterflow principle, is integrated into the coolant circuit immediately after the compressor (1) and the heat exchanger (6) is thermally protected against heat loss by insulation material becomes. The coiled coaxial tubular heat exchanger claim 2 In contrast to the state of the art (Figures 2 and 3), the design is changed so that the inlet and outlet openings are in a line opposite each other ( 2 ). the power gain of the refrigeration machine according to the claims 1 until 4 for machines/devices that work with the heat pump principle, in the private and industrial sector, both stationary and mobile.

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