WO2011057373A1

WO2011057373A1 - Refrigeration compressor

Info

Publication number: WO2011057373A1
Application number: PCT/BR2010/000373
Authority: WO
Inventors: Fernando Antonio Ribas Junior; Rodrigo Kremer
Original assignee: Whirlpool S.A.
Priority date: 2009-11-10
Filing date: 2010-11-09
Publication date: 2011-05-19
Also published as: EP2500567A1; US20130045119A1; BRPI0904785A2; CN102667157A; KR20120103605A

Abstract

A refrigeration compressor comprises a housing which surrounds the component parts of said compressor. A heat accumulating material (6), which can be arranged within or adjacent to the compressor housing, acts as a thermal capacitor being able to absorb heat while the compressor is on and to release heat while the compressor is off, so as to increase the thermal efficiency of the compressor. The heat accumulating material can be a phase change material (PCM).

Description

"COOLING COMPRESSOR"

Field of the Invention

The present invention relates to a refrigeration compressor, and more specifically to a compressor whose cooling is performed by utilizing the characteristics of its thermal transient when such a compressor is applied to a refrigeration system.

Background of the Invention

A compressor has the function of raising the pressure of a given volume of fluid to a pressure necessary to perform a refrigeration cycle. For the refrigeration industry, it is common to use hermetic compressors that generally comprise a sealed housing on which compressor parts are mounted: a compressor-motor assembly comprising a cylinder block with an end closed by a head defining a discharge chamber in communication with a compression chamber defined within the cylinder, the compression chamber is closed by a valve plate provided between the cylinder end and the head.

During compressor operation, the heat generated by the gas compression eventually heats up the compressor component parts.

The refrigeration industry is very concerned about the performance of refrigeration compressors. In fact, several studies and studies have been carried out to improve such performance, especially those aiming at increasing the amount of gas aspirated in the suction and reducing the power required to compress the gas.

These solutions demand a decrease in the suction gas temperature (increasing its specific mass) and a decrease in the compression chamber wall temperature in contact with the gas. In this sense, it is understood that the development of solutions that promote the reduction of compressor temperature levels act directly on the increase of volumetric and energetic efficiency, the latter being due to the thermodynamic portion (reduction of overheat losses and increase of process efficiency). compression).

Over the years, various thermal concepts have been applied in order to reduce internal compressor temperature levels.

One such concept is the isolation of the discharge system, which is one of the major sources of compressor internal heating. Solutions that address this type of approach can be found in US 3,926,009 and US 4,371,319, which explore discharge insulation by applying double wall concepts (thermal insulation through confined space).

WO 2007/068072 uses the concept of insulation of cylinder heating sources. According to this document, a conduit is constructed spacer over the valve plate and open into the internal cavity of the compressor housing, keeping the compressor cylinder cap away from the valve plate and forming an annular plenum around the spacer duct. In this way, heat transmission from the cylinder cover to the valve plate is reduced, which ultimately reduces the heating of the cylinder block in the region of the compression chamber, increasing the efficiency of the compressor.

Another way to manage the internal thermal dynamics of the compressor is by the addition of heat transport elements to remove heat from the sources that have the greatest influence on the thermal efficiency of the compressor and to move this heat to regions far away from them. Within this concept, mention should be made of WO 2007/014443, which proposes a solution for increasing compressor efficiency that utilizes heat pipes to remove heat from hot parts in contact with the cylinder. This document proposes an airtight compressor with heat dissipation system in which a thermal energy transfer conduit is coupled to the cylinder block. The conduit having a heat-absorbing end on the cylinder and another heat-releasing end disposed away from the cylinder block to absorb heat generated by compressing refrigerant within the cylinder and dissipating it to a remote region thereby decreasing the cylinder temperature and also increasing the efficiency of the compressor.

Another possible solution for reducing the temperature of the compression cylinder is to make better use of compressor lubricating oil as a cooling medium. Oil currently has as its main function to lubricate the compressor mechanism to ensure the reliability and durability of its parts. Based on the use of oil for cylinder cooling purposes, US 4,569,639 may be indicated, in which the inventors propose the use of a shaft outlet extension and a cylinder head deflector to direct the cylinder oil flow from the shaft extension to the cylinder head, causing the cylinder to cool. This cylinder extension has a hole through which oil is jetted horizontally towards the cylinder head deflector while this extension is rotated. The deflector also has a hole at a height approximately equal to the height at which the oil is spouted, causing the oil to drain over the cylinder head to cool it.

Through the description of the prior art given above, it is observed that different concepts and solutions have been applied with the intention of reducing internal compressor temperatures, however it should be emphasized that such solutions have been developed with the focus on the compressor viewed as a thermal machine in isolation. .

Objectives of the Invention

The present invention aims to promote compressor cooling using characteristics of the compressor's thermal transient when applied to a refrigeration system.

Thus, the present invention takes advantage of the existing thermal dynamics between the compressor and the compression system, reliably and efficiently reducing internal temperatures and thereby improving compressor performance.

Summary of the Invention

The present invention achieves the above objectives by means of an airtight compressor comprising a housing that surrounds the compressor component parts, with a heat accumulating material occupying an internal volume or adjacent to the compressor housing. The heat accumulating material acts as a thermal capacitor capable of absorbing high amounts of heat during the compressor on time and rejecting heat during the compressor off time in order to increase the thermal efficiency of the compressor.

In one embodiment of the invention, the heat accumulating material rejects heat a first amount of heat during the compressor on time and a second amount of heat during the compressor off time. In this sense, the heat accumulating material may reject a minimum amount of heat during the compressor on time and a high amount of heat during the compressor off time.

It should also be noted that heat accumulating material can absorb heat during the compressor on time and discard part of this heat to one of the compressor components during the compressor off time.

The heat accumulator material may be a latent heat accumulator or a sensitive heat accumulator, however, the use of a PCM (phase shift material) is particularly advantageous for the proposed inventive concept.

In this sense, it is emphasized that, for the present invention, PCM comprises all the material that at a given design temperature begins to receive latent heat, that is, a process at practically constant temperature, and with high heat absorption capacity. In this sense, although a PCM material is usually defined as a material that undergoes a change in the liquid phase and the solid phase, there are a few PCM material that, instead of phase shifting, change the structure of matter, these being PCM ^' are called solid-solid. Thus, although phase change is mentioned throughout the text, the PCM nomenclature also covers materials that change structure at a given design temperature, absorbing high heat rates.

The heat accumulating material may occupy an idle volume inside the compressor, or even be part of the structure of at least one of the parts of the compressor. compressor.

Brief Description of the Drawings

The figures show:

Figure 1 - Figure 1 illustrates a first constructive possibility for the refrigeration compressor of the present invention;

Figures 2 and 3 - Figures 2 and 3 illustrate result graphs of a numerical simulation indicating the heat removal obtained through the constructive possibility illustrated in Figure 1;

Figure 4 - Figure 4 illustrates a second constructive possibility for the refrigeration compressor of the present invention;

Figures 5a to 5c - Figures 5a to 5c illustrate a third constructive possibility for the refrigeration compressor of the present invention;

Figure 6 - Figure 6 illustrates a fourth constructive possibility for the refrigeration compressor of the present invention;

Figure 7 - Figure 7 illustrates a fifth constructive possibility for the refrigeration compressor of the present invention;

Figure 8 - Figure 8 illustrates a sixth constructive possibility for the refrigeration compressor of the present invention;

Figure 9 - Figure 9 illustrates a seventh constructive possibility for the refrigeration compressor of the present invention;

Figure 10 - Figure 10 illustrates an eighth constructive possibility for the refrigeration compressor of the present invention;

Figures 11a to 11b - Figures 11a and 11b illustrate a ninth constructive possibility for the refrigeration compressor of the present invention; and

Figure 12 - Figure 12 illustrates a tenth constructive possibility for the refrigeration compressor of the present invention.

Detailed Description of the Invention

The present invention will hereinafter be described in more detail based on the exemplary embodiments shown in the drawings. While the detailed description uses an alternative refrigeration compressor as an example, it should be understood that the principles of the present invention may be applied to any type, size or configuration of refrigeration compressor. Thus, the present invention may be applied to hermetic or semi-hermetic reciprocating compressors, rotary or scroll compressors or any type of refrigeration compressor capable of receiving a volume of a heat accumulating material acting as a thermal capacitor.

When a compressor starts its operation, heat generation starts in several components, such as the engine, the compression cylinder and the discharge region. When the compressor is observed in a thermally stabilized regime, all the energy generated by the hot components is dissipated to the others. However, during warming periods (when temperatures are still rising), much of the energy generated, rather than being dissipated, is absorbed by the component itself, with the aim of raising its internal energy and therefore its temperature. This energy storage capacity during the transient period is directly related to the heat capacity of the respective component. Imagining a component with an infinite-tending calorific capacity would be practically constant because it would take a lot of energy to raise it. In this ideal scenario, the component would practically work at the initial temperature, which would lead to zero dissipated heat, not heating the other components.

When looking at a compressor operating at a steady temperature range (a fairly long uninterrupted operating time), the heat capacity no longer plays any role as it only serves to change the heating time of the components.

However, when observing the application of the compressor in the refrigeration system, due to the dynamic characteristics of this system, the compressor does not run uninterrupted. It goes through a cycling process, and in some cases stays off longer than on. Thus, the temperatures of the compressor internal components during operation in the refrigeration system do not stabilize.

The present invention is based on the use of elements capable of absorbing heat from hot components during the compressor operating period. The use of these elements directly impacts the temperature reduction of these components, increasing the thermodynamic efficiency of the compressor. In fact, the present invention reveals a compressor thermal management mechanism that makes use of the thermal behavior of its components when in a refrigeration system, achieving a decrease in compressor heating during its on period.

Thus, for the concept proposed by the present invention to be applied efficiently, it is necessary to contextualize it in its application in refrigeration systems.

Assuming a compressor having elements of high heat capacity and running uninterruptedly, the temperature of these elements would increase continuously and the range of temperature reduction would not occur. However, when looking at the actual duty cycle of a compressor in the refrigeration system, there is a good period in which the compressor is off, and in this period, there may be sufficient time for the energy absorbed by these high heat capacity elements. lost to the compressor environment and from the compressor to the outside environment. Thus, considering the actual operating cycle of a compressor in the refrigeration system, it is noted that it is possible to reach a closed cycle, where the thermal energy absorbed by the high heat capacity elements is rejected before a new on-time period. .

The term "high heat capacity elements" is used herein to mean heat absorbing elements, and a different range of materials could be used for making such elements.

Likewise, although the term "elements" is used, the present invention is based on the use of heat accumulating materials occupying an internal volume or adjacent to the compressor casing and is not limited to an "independent element" to be inserted. in the internal space of the compressor.

An intrinsic advantage associated with the use of phase shifting heat absorbing elements is that they work at practically constant temperatures during the heat absorption process (this enhances this absorption and prevents these components from heating the others as well). In addition, once the operating temperature of these components is specified (by selecting a material with the desired phase change temperature), it is possible to adjust the operating temperature of the internal components to an optimal point based on system dynamics. , achieving greater control over the solution.

Therefore, it is desirable to use a heat absorbing material which works at a constant and presettable temperature.

In view of the above needs and advantages, in a preferred embodiment of the present invention, a phase shifting material is used during the heat absorption process (latent thermo-accumulator). These materials, known as Phase Change Materials (PCMs), include paraffins, special greases, and other components that can be manufactured to phase-change at different design temperatures. Again, although most phase changes will be solid-liquid, changes in the structure of matter (solid-solid PCM) that also absorb high amounts of heat at a design temperature are also within the scope of the design. present invention.

Besides the possibility of controlling the phase change temperature, through the composition of the material employed, this process has a high energy absorption capacity with practically constant temperature, as opposed to a sensitive thermal accumulation process, which implies variations considerable temperatures.

Of course, although the preferred embodiment of the present invention employs

PCMs, the use of other high heat specific materials may also be used as they are also able to absorb heat with slow temperature (sensitive heat accumulators). An example of a specific high heat material that can be applied to the extent of the advantages provided by the present invention is water.

It is to be understood that the present invention is based precisely on the addition of a heat accumulating material occupying an internal volume or adjacent to the compressor casing. Thus, this material (either a PCM or any other material with high heat capacity) can be employed at various compressor locations, and this position must be determined according to the effectiveness in reducing internal component temperatures in the space available for allocate these components, the cost involved and the technological challenges to that end.

In accordance with the fundamental principles of the present invention, the heat accumulating material acts as a thermal capacitor, absorbing high amounts of heat during the compressor on time and rejecting that heat during the off time.

The dynamic behavior of this "thermal capacitor" can take two forms: it can absorb high amounts of heat by rejecting as little of the compressor on time as possible, then rejecting heat in an off time, or it can absorb large amounts of heat in an on time and maintain a uniform heat removal rate over the on and off times. In the latter form, although there is a heat rejection during the compressor on time, the energy removal generated is much greater during this same period, contributing to the lowering of the thermal profile.

The presence of either dynamic characteristic will depend on the heat input and output contour conditions (convection coefficients and temperature potential), and will vary by design.

Figure 1 shows a first embodiment of the present invention, wherein the heat accumulating material is located in a volume formed between a cap surrounding the cylinder cover and the compressor cylinder cover.

This cylinder cover region is a critical region for the compressor as it is where various gas communications pass. Suction gas to enter the cylinder passes through the suction muffler region in contact with the cylinder cap. High-temperature compression gas is also discharged into the cap from where it goes to the rest of the discharge system. Thus, by removing heat from the gas in the cylinder lid and thereby lowering its temperature, lower heat will be observed at the suction muffler outlet and heat dissipation throughout the entire downstream discharge system is since the temperature potential between this same gas and the internal environment of the compressor decreases. In addition, the lid, when cooled, absorbs more heat from the cylinder, which acts in favor of the thermodynamic efficiency of the compressor. In Figure 1, a part of a compressor is illustrated, showing the cover 1 surrounding the lid 2 of the cylinder 3. Within the space formed between the cover 1 and the lid 2 a volume 4 is created, where the accumulator material is stored. heat (as mentioned earlier, this material can be a grease, a paraffin, another type of PCM, or even another high heat capacity material).

As can be seen in figure 1, the cover 1 may further comprise external fins 5. The option to add fins 5 derives from the system's own thermal dynamics: The heat input in this system is very intense as the gas from the cylinder cap collides with the walls of the lid at high speed, generating a high heat transfer rate. In order to reject heat to the compressor internal environment, gas velocities are slower, especially in compressor off time, when the internal gas only moves by natural convection. In order to be able to reject all heat absorbed at high rates in the on time period, the external heat transfer area is increased by the addition of the fins 5. One may also choose to include a dark paint on the cover 1 and the fins 5, in order to increase heat transfer by radiation.

It should be noted, however, that the addition of fins 5 is a constructive preference and is not necessary to achieve the advantages obtained by the addition of a heat accumulating material in the volume formed between cylinder cover 2 and cover 1.

Likewise, the fins could be internal fins, adjunct to the thermo-accumulating material, which would facilitate the flow of heat along its structure. As some materials have low thermal conductivity, the addition of fins allows for the maximization of heat flow throughout the material. In addition, other solutions for maximizing heat transfer throughout the heat exchanger material could also be used within the scope of the present invention, such as porous metal matrices injected together with the heat accumulator.

In order to prove the efficiency of the present invention, a numerical simulation was performed indicating the heat removal potential of a compressor cylinder cap using the concept of the embodiment shown in Figure 1 (wherein the heat accumulating material is located in a volume formed between a cap that surrounds the cylinder cap and the compressor cylinder cap.)

Figures 2 and 3 show graphs illustrating the results of the simulation performed (in figures, line A corresponds to the embodiment with the volume of heat accumulating material and line B corresponds to a conventional compressor).

Figure 2 shows a graph illustrating the rejected heat from the cylinder cover to the compressor internal environment. Although it seems that the lid with the heat accumulating material dissipates more heat than the normal lid the heat removed from the gas should be analyzed. refrigerant inside the cylinder cover. This analysis, illustrated in figure 3, shows that during the compressor on time (ON time in the figure) the accumulator element dissipates approximately 3 W more than the normal cap, but during this same period the system removes 8 W more of the gas. . Thus, in the overall balance, a gas cooling is obtained, and therefore a lowering of the compressor thermal profile, which contributes to the increase of energy efficiency.

The graphs in figures 2 and 3 can be interpreted by the following analysis of system behavior: Heat enters the accumulating material from a gas at high temperature and velocity. To discharge the same heat inside the compressor, more time is needed as it is discharged to a gas at a lower speed (low convection coefficient) and with a lower temperature potential. As such, it takes more than the compressor on time to close the heat charge and discharge time, and thus ends up having a continuous discharge process, but with a much more intense gas heat absorption in the compressor on period (period to be considered for the purpose of the present invention).

Figure 4 illustrates a second exemplary embodiment of the present invention. In this embodiment, the heat accumulating material is added to the compressor discharge system.

As can be seen from Figure 4, in that embodiment, a heat accumulating material wrapper 6 is added to a discharge volume V downstream of the cylinder cap 2. Thus, a concentric cap 7 is welded to the discharge tube, creating a hermetic volume in which the heat accumulating material is deposited. It should be emphasized that the main advantage of this embodiment is precisely in its simple construction.

One of the benefits of adding heat build-up material to the discharge path, either on the cylinder cover or some downstream component, is that depending on the design optimization, greatly reducing the gas temperature at the compressor outlet, it will have to reject less heat in the system condenser, which will lower the condensing temperature (and pressure), and therefore increase the efficiency of the overall cycle as the difference between the source temperatures is decreased. hot (condenser) and cold source (evaporator).

Similar to the above with respect to the first constructive possibility, such embodiment shown in figure 4 may include fins 5, preferably disposed externally and integrally with the concentric shell 7. The presence of these fins increases the external area and, consequently, assists the removal of heat during the compressor off time.

As mentioned with respect to the first embodiment of the invention, internal fins could be added to maximize heat transfer along the matrix of the thermal accumulator.

Figures 5a, 5b and 5c show a third embodiment of the present invention, where heat accumulating material is employed externally to the compressor crankcase region 8.

As illustrated in Figure 5a, in this embodiment a phase shifting material volume 6 is arranged at the bottom of the compressor in a volume isolated from the internal environment of the compressor. This volume may take the form of a reservoir 9 to be closed by a glue welding process, or other forms which ensure the hermeticity of the region in question to ensure a seal between the internal volume of the compressor and the volume of the term accumulator. .

As shown in figures 5a to 5b, this reservoir 9 may include metal fins 10 in the volume region of the heat accumulator, with the aim of facilitating heat transfer of the heat accumulator material to the external environment, maximizing the efficiency of the heat transfer process. heat discharge.

The embodiment shown in figures 5a to 5c has two major advantages: When cooling the oil, passing through the other components of the compressor, being at a lower temperature, removes more heat from them, resulting in a cooling of these components (including the cylinder region and suction filter). If the compressor has a construction where cylinder and head are located near the oil, the effects of adding this type of accumulator in this region are even greater because the cooling of oil and surrounding regions reaches the compression cylinder more effectively. .

In addition, during compressor operations in the refrigeration system, compressor components, in this case oil, may undergo very different temperature regimes. In a pull-down test (critical situation) the oil is extremely hot and in a power consumption test it is much colder. Thus, the oil viscosity is quite different in one regime and another, affecting the entire bearing design and not allowing precise optimization of these components. The addition of phase-shifting thermal accumulators at a given temperature allows them to be adjusted to remove more heat at high temperature regimes and thereby reduce the oil temperature at critical pull-down regimes. by approximating pull-down operating point temperatures and power consumption. As a result, variations in oil viscosity in the application are reduced, allowing for a more optimized bearing design, which ultimately increases the energy efficiency of the compressor.

A fourth exemplary embodiment of the present invention involves the addition of heat accumulating material in a region on the outside of the compressor casing. such region being generated integrally with the compressor baseplate.

Such an embodiment, shown in Figure 6 comprises creating a wrapper 11 formed in correspondence with the compressor base plate 12, adjacent to the outside of the compressor crankcase region 8.

Thus, the wrap body 11 takes advantage of part of the base plate 12, and facilitates the assembly assembly process.

Similar to that discussed with respect to the other embodiments, the outer wall of the wrap 11 may be provided with fins 13 for the purpose of facilitating heat transfer and maximizing the efficiency of the heat dissipation process to the external environment.

A fifth exemplary embodiment of the present invention involves adding the heat accumulating material to a wrap 14 formed in the region of the compressor housing 8, the wrap 14 being internal to the compressor.

This embodiment, shown in Fig. 7, comprises a wrapper partially defined by the inner wall of the housing and an additional wall 15, the wrapper 14 thus defined being in a region immersed in the compressor oil.

Similar to that discussed with respect to other embodiments, the wrapping wall 14 may be provided with fins 16 for the purpose of facilitating heat transfer and maximizing process efficiency.

As mentioned above with respect to the third exemplary embodiment of the present invention, the application of oil heat accumulators in the crankcase region may have two major advantages, according to the focus of that application:

By promoting oil cooling during the compressor's current operation, the thermal accumulator material intensifies the amount of heat it removes from the components, allowing a reduction in the compressor's temperature levels, resulting in increased energy and volumetric efficiency. .

By promoting oil cooling focused on critical application conditions, it allows to reduce temperature differences from critical condition to nominal application condition, facilitating engine design and optimization (as it decreases viscosity variability)

The application of the thermal accumulator in the crankcase region has the facility of having the entire base region of the housing plus the base plate as dissipating elements of the heat stored during the compressor operating time, which makes the capacitor discharge process easier to perform.

In this sense, the application of a latent thermal accumulator (specifically a phase change material - PCM) is very interesting for this scenario, because, besides In order to be used in order to lower the suction chamber and cylinder temperatures, this material could be used for oil temperature control and modulation. By designing the application focusing on the compressor crankcase region, it is understood that it is possible to accumulate the thermal energy of the oil over a specified temperature range in order to prevent overheating under extreme conditions (through PCM heat absorption). ), thus approximating the application viscosity levels in relation to extreme situations.

This result has a direct impact on the reduction of design constraints (need to simultaneously meet critical conditions and nominal application conditions), facilitating the development of new energy efficient mechanisms.

In this regard, it should be noted that the embodiments of the invention shown in FIGS. 5 and 6, where the heat accumulating material is disposed in a region near the housing, have advantages similar to those described above over the embodiment of FIG. 7.

Figure 8 shows a sixth exemplary embodiment of the present invention where heat accumulating material is added to the suction muffler.

As can be seen in that figure, in that embodiment, a wrapper containing heat accumulating material 18 is provided in the suction tube 19 of the suction filter 20 of the compressor.

Thus, the heat accumulating material acts to cool the gas as it passes through tube 19, decreasing its temperature at the cylinder inlet, with a consequent increase in volumetric and energy efficiency.

If the heat accumulator material is a latent thermoaccumulator (PCM), the phase change temperature should be less than the gas temperature in the pipe region to generate a favorable heat removal temperature potential.

It should be noted that the heat accumulator material could be a sensitive heat accumulator (eg water or oil), in which case the design needs to be well designed taking into account temperature variations both in the process of absorption, as in the process of heat dissipation by the thermal accumulator matrix. The option of applying the thermal accumulator to the suction muffler can be explained by the characteristics of the system: an important source of compressor energy inefficiency is gas overheating during suction, and is based on useless heating of the gas during the travel of the compressor. suction dowel up to the compression cylinder. Important increases in efficiency have been observed in the past with the change of metal suction filters by plastic suction filters. Today virtually all compressors for household refrigeration application apply plastic filters, but even so the Gas temperature at cylinder inlet is about 20 to 30 ° C higher than temperature at compressor inlet.

Thus, in the sixth embodiment of the present invention, the thermoaccumulating material acts to cool the gas as it passes through the suction tube 19, decreasing its temperature at the cylinder inlet, with consequent increase in volumetric and energy efficiency.

If a latent thermal accumulator (PCM) is used, the phase change temperature should be less than the gas temperature in the pipe region to generate a favorable heat removal temperature potential. One can opt for a sensitive heat accumulator (water or oil for example), however, this design needs to be well designed to ensure thermal discharge of the heat accumulator. During compressor shutdown time.

Similarly to the other constructive examples of the present invention, the fins present in the drawing are only a constructive option and may or may not exist depending on the design of the application of the thermal accumulator. The presence of such fins comes with the objective of intensifying the heat removal (by increasing the area) of the pipe gas to the thermo-accumulator region.

Combined suction filter material solutions and heat accumulators can be developed to maximize heat removal performance. For example, the use of a suction cap (which contains, for this project, the suction tube) of metallic material (eg steel or aluminum), allowing a lower thermal resistance of the gas with the PCM. .

Figure 9 shows a seventh exemplary embodiment of the present invention, wherein heat accumulating material is applied to the region of the compression cylinder 3.

In this embodiment, retention channels 23 for heat accumulating material 24 are formed along the cylinder. As shown in the figure, the channels 23 may be closed by sealing the head itself 22. However, the channels may alternatively be closed by welding, gluing, or any other suitable means.

When the heat accumulator material is a latent fear accumulator (PCM), it is possible to control the characteristics of the material to act on the removal of heat during the normal period of compressor operation, resulting in a reduction in cylinder temperature and consequently of the gas contained in it. This reduction has a direct impact on the energy efficiency increase of the compressor. For example, if the cylinder operates nominally at a temperature of 90 ° C, this material could be designed to phase shift at 60 ° C and intensify heat transfer, making the new cylinder temperature less than 90 ° C. C, resulting in an increase in thermodynamic efficiency. Another possible application for the cylinder region would be the addition of a material with a phase change temperature greater than continuous operating temperature but lower than during critical operating periods to adjust the proper operation of the thermal accumulator at steady state. operating conditions, such as under high thermal stress regimes. This would have the benefit of product robustness, as allowing the cylinder 3, piston 21 and oil in this region to work cooler under these regimes improves the lubrication and bearing process. In addition, efficiency can be increased indirectly, as by having more robustness in extreme conditions, some design criteria can be relaxed (such as reducing oil viscosity, as at high temperatures PCM ensures adequate viscosity). ), allowing better operation of the compressor under normal operating conditions.

Similar to the other embodiments described, the presence of the fins is optional and dependent on the project in question. In said constructive form illustrated in the figure, the fins 25 were added with the aim of facilitating the thermal discharge, by increasing the exchange area, of the thermal-accumulating matrix (which may be latent - PCM - or sensitive) since the loading thermal, due to the high convection inside the cylinder, is more intense than the internal environment side of the compressor.

Figure 10 shows an eighth exemplary embodiment of the present invention, where heat accumulating material is added to a wrapper or cylindrical jacket 27 of the compressor electric motor (see Figure 10, where numeral 25 indicates the rotor and numeral 26 the stator ).

In the illustrated embodiment, such cylindrical sleeve 27 is interference-mounted on the outer region of stator 26 to minimize the inherent thermal resistances of these types of mounting.

Thus, as the engine warms up, and when it reaches a certain working temperature specified in the application of the thermal accumulator, it would absorb the heat dissipated by the engine, forcing it to work at a lower temperature than it would work. without the presence of the thermal accumulator.

In addition to the cooling of the motor itself, the presence of the thermal accumulator prevents the heat dissipated in this component from reaching the internal environment of the compressor, causing cavity temperature reductions, and indirectly energy losses due to gas overheating.

Another advantage of this solution is the possibility of guaranteeing the reliability of compressors that work in a critical temperature regime, such as compressors with low electrical efficiency, in order to save steel and especially copper (low cost compressors).

In the embodiment illustrated in the figure no dissipative fins were added, however, such fins could be added within the inventive concept of the present invention.

Figures 11a and 11b show a ninth exemplary embodiment of the present invention where heat accumulating material is applied to the suction dowel 28, the discharge dowel 29, or both suction and discharge dowels 28,29. (dowels)

The application of heat accumulators to the suction drawer has at least two advantages. The first concerns the overheating of the suction gas even before entering the compressor, due to the heating of this strainer by the higher temperature housing. This heat flow when walking through the strainer encounters less resistance in the suction gas, which has a much higher heat transfer coefficient than the outside, as the latter is typically CHARACTERIZED as natural convection. The addition of heat-accumulating material in a wrapper 30 around the suction dowel 28 seeks to create a preferred path for the heat flux from the casing, other than the suction gas. Thus, the addition of fins 31 may increase the exchange area for the thermal accumulator.

Another advantage of this application is that it creates an obstacle to heat from the discharge dowel 29, which is much hotter than the suction dowel 28 and the housing itself. In some compressors, for design needs, suction and discharge dowel 28 are very close 29 (see, for example, the illustrated exemplary embodiment). Thus, a thermal short circuit is to be expected as there is a high temperature gradient between the exhaust gas and the suction gas. However, the presence of this thermo-accumulating element also acts to create a preferential path to heat from this component.

This same effect is desired when applying this thermo-accumulator 32 to the discharge dowel 29, generating a preferred heat path other than that which carries this thermal energy to the suction region. Likewise the presence of the fins 33 fulfills the role of facilitating this heat transfer to the heat accumulator matrix.

Another intrinsic advantage of applying the thermal accumulator 32 to the discharge pass 29 is the lowering of the discharge gas temperature because the thermal dissipation for this accumulator becomes intensified. By lowering the discharge temperature, there may be indirect efficiency gains as the need to exchange this heat in the condenser decreases. As a result of this reduction of heat to be exchanged in the condenser, the condenser size can be reduced (cost reduction) or, if the condenser size is maintained, the pressure and saturation temperature in the condenser decreases, increasing the cycle efficiency. thermodynamic. As possible constructive variants, the envelope for the thermal accumulator could be made of metal and / or plastic, being that in the metallic version it could be welded or in the housing and the dowel. In the case of the plastic option, glue would be the first viable option.

Figure 12 shows a tenth exemplary embodiment of the present invention, where heat accumulating material is applied to the top 35 of the compressor casing.

Thus, in the illustrated embodiment, a preferably metallic plate 36 is superimposed on the compressor cover, such components being joined by any suitable means (e.g. welding or gluing), ensuring the creation of an airtight wrap to house the accumulator material. heat 37.

As a result of the application in this region, it works at a lower temperature level than the nominal carcass, absorbing more heat from the internal environment, decreasing the internal temperature and consequently the losses of gas overheating during the suction process. .

As mentioned in relation to the other illustrated embodiments, plate 36 may comprise fins 38, which aim to increase the heat exchange area.

It is to be understood that the description provided on the basis of the figures above refers only to possible embodiments for the refrigeration compressor of the present invention, and the actual scope of the object of the invention is defined in the appended claims.

In this sense, it should be understood that the inventive concept underlying the present invention lies precisely in taking advantage of the thermal dynamics existing between the compressor and the refrigeration system to achieve a reliable and efficient reduction of the internal temperatures of the compressor and, consequently, to improve the compressor performance.

This inventive concept is performed by a refrigeration compressor comprising a heat accumulating material that acts as a thermal capacitor in order to increase the thermal efficiency of the compressor.

Although any type of heat accumulator material (e.g., a latent heat accumulator or a sensitive heat accumulator) may be used within the concept of the present invention, the above description makes it clear that the present invention is particularly efficient with the use of a latent thermal accumulator in the form of a phase shift material (PCM).

The position of the heat accumulator material and the means of use thereof in the construction of the compressor are design dependent characteristics of the compressor, and the embodiments illustrated in the detailed description are only examples of possible embodiments. In this sense, the figures show embodiments in which the heat accumulating material (preferably a PCM) is applied in an idle volume within the compressor housing - either in a specifically formed wrapper, in a space formed between components. or even in confined spaces formed within the compressor components, or in a volume externally adjacent to the compressor casing. It should be noted, however, that the present invention is not limited to the constructive possibilities described herein.

For example, the present invention may, instead of utilizing a volume created between two plates, for example, use an elastic PCM material contained within ("rubber sheet"), which material could be attached to the compressor casing, by glue or other means of adhesion. This variant would allow the exchange of PCM material over time.

In addition, the heat accumulating material (preferably a PCM) could, for example, be directly used in the manufacture of one of the compressor components or in the compressor housing.

Similarly, the fins provided in the described embodiments may be external, as shown in the figures, or internal, adjoining the heat-accumulating material, to facilitate heat flow along its structure. As mentioned throughout the text, the addition of fins allows for the maximization of heat flow throughout the material. In this regard, it should be emphasized that other solutions for maximizing heat transfer throughout the thermo-accumulator material could also be used within the scope of the present invention, such as porous metal matrices injected together with the thermo-accumulator.

While the present invention may use any type of heat accumulator material, the following examples of PCM material that may be used within the scope of the present invention are listed for information purposes: models RT52 and RT65 by manufacturer Rubitherm Technologies GmbH, models Plus Ice - S58 and S72 (hydrated salt-based PCM solutions) and Plus Ice models A55, A62 and A70 (organically based PCM solutions) from Phase Change Material Products Limited, and Climsel C58 and Climsel C70 models from Climator Sweden AB.

Claims

1. A refrigeration compressor comprising a housing that surrounds the compressor component parts, characterized by the fact that it comprises a heat accumulating material acting as a thermal capacitor capable of absorbing high amounts of heat during the compressor on time and rejecting heat during the compressor. compressor off time, so as to increase the thermal efficiency of the compressor.

Compressor according to claim 1, characterized in that the heat accumulating material rejects a first amount of heat during the compressor on time and a second amount of heat during the compressor off time.

Compressor according to claim 2, characterized in that the heat accumulating material rejects a minimum amount of heat during the compressor on time and a high amount of heat during the compressor off time.

Compressor according to claim 1, 2 or 3, characterized in that the heat accumulating material absorbs heat during the compressor on time and rejects part of this heat to one of the compressor components during the compressor off time.

Compressor according to any one of claims 1 to 4, characterized in that the heat accumulating material is a latent heat accumulator.

Compressor according to any one of claims 1 to 4, characterized in that the heat accumulating material is a sensitive heat accumulator.

Compressor according to any one of claims 1 to 6,

The heat accumulating material occupies an internal (4, 7, 15, 18, 23, 27) or adjacent (9, 11, 30, 32, 37) volume to the compressor casing.

Compressor according to claim 7, characterized in that the heat accumulating material occupies an idle volume inside the compressor.

Compressor according to claim 7, characterized in that the heat accumulating material is part of the structure of at least one of the compressor parts.

Compressor according to claim 8, characterized in that the heat accumulating material is arranged in a volume (4) formed between a cover (1) surrounding a cover (2) of the compressor cylinder (3) and the cover (2) of the compressor cylinder (3).

11. Compressor according to claim 8, characterized by the fact that The heat accumulating material occupies an airtight volume (6) formed by a substantially concentric cap (7) to the compressor discharge pipe.

Compressor according to claim 7, characterized in that the heat accumulating material is disposed in a reservoir (9) adjacent to the bottom of the compressor.

Compressor according to Claim 7, characterized in that the heat-accumulating material is disposed in a wrapper (11) formed in correspondence with a compressor baseplate (12), the wrapper (11) being external to the compressor. and being at least partially formed by part of the base plate (12).

Compressor according to claim 8, characterized in that the heat accumulating material is disposed in a wrapper (14) formed in the inner region of a compressor casing (8), wherein the wrapper (14) is defined between an inner wall of the compressor housing and an additional wall (5).

Compressor according to claim 8, characterized in that the heat accumulating material is disposed in a wrapper (18) provided in a suction tube (19) of a compressor suction filter (20).

Compressor according to claim 8, characterized in that the heat accumulating material is disposed in a cylindrical jacket (27) formed in the electric motor of the compressor.

Compressor according to claim 7, characterized in that the heat accumulating material is disposed in an airtight wrapper (37) formed by the compressor top wall and an additional plate (36).

Compressor according to claim 9, characterized in that the heat accumulating material is disposed in retaining channels (23) formed along a compressor cylinder.

Compressor according to claim 9, characterized in that the heat accumulating material is applied to a suction dowel (28) of the compressor.

Compressor according to claim 9 or 19, characterized in that the heat accumulating material is applied to a compressor discharge duct (29).

Compressor according to any one of claims 1 to 20, characterized in that the heat accumulating material has internal fins for maximizing the heat flow throughout the material.

Compressor according to any one of claims 1 to 20, characterized in that the region surrounding heat accumulating material has outer fins for maximizing heat transfer with the outer region.

23. Refrigeration compressor comprising a housing that surrounds the compressor component parts, characterized in that it comprises a phase shift material (PCM) occupying an internal (4, 7, 15, 18, 23, 27) or adjacent (9, 11, 30, 32, 37) volume to the compressor housing, the phase change material (PCM) acting as a thermal capacitor capable of absorbing high amounts of heat during the compressor on time and rejecting heat during the compressor off time in order to increase the thermal efficiency of the compressor. compressor.

Compressor according to claim 23, characterized in that the phase shift material (PCM) occupies an idle volume within the compressor.

Compressor according to claim 23 or 24, characterized in that the phase shift material (PCM) is part of the structure of at least one of the compressor parts.