JP2009204208A - Refrigeration device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigeration device for accurately estimating high-pressure side pressure by temperature of refrigerant and easily improving the operation efficiency. <P>SOLUTION: The refrigeration device (1) includes refrigerant temperature detection means (20, 22, 24) for detecting the refrigerant temperatures of an inlet part (14), an outlet part (16), and an intermediate part (18) positioned between the inlet/outlet parts of a radiator (6), a high-pressure side pressure estimating means (26) for estimating the high-pressure side pressure of the refrigerant in a high-pressure route part (2a) based on the refrigerant temperatures of the inlet part, the outlet part, and the intermediate part detected by the refrigerant temperature detection means, and a control means (26) for controlling at least either a compressor (4) or an expansion valve (8) to set the high-pressure side pressure of the refrigerant estimated by the high-pressure side pressure estimating means to be predetermined target high-pressure side pressure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus, and more particularly, to a refrigeration apparatus suitable for being incorporated in an air conditioner or a heat pump type water heater using a carbon dioxide refrigerant.

This type of refrigeration system has a high-pressure path from the compressor to the expansion valve through the radiator and a low-pressure path from the expansion valve to the compressor through the evaporator, and contains carbon dioxide refrigerant that can be in a supercritical state. The refrigerant circulation path is provided, and the refrigerant temperature at the inlet and outlet of the radiator is detected to estimate the high-pressure side pressure of the refrigerant in the high-pressure path, and the compressor rotation speed and the The opening degree of the expansion valve is controlled (for example, refer to Patent Documents 1 to 3).
JP 2007-155157 A JP 2002-81766 A Japanese Patent No. 2931668

However, in each of the above prior arts, no particular consideration is given to the amount of heat released from the refrigerant that changes in the radiator, in other words, the amount of heat exchange between the refrigerant and the medium to be radiated. There is a problem that the high-pressure side pressure cannot be accurately estimated and the refrigeration apparatus cannot be operated efficiently.
Therefore, it is conceivable to directly measure the high-pressure side pressure with a pressure sensor. However, the pressure sensor is expensive, and there is a problem that the cost of the refrigeration apparatus increases because the assembly cost of the refrigeration apparatus increases.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a refrigeration apparatus that can accurately estimate the high-pressure side pressure based on the refrigerant temperature and can simply improve the operation efficiency.

  In order to achieve the above object, the refrigeration apparatus according to claim 1 has a high-pressure path section extending from the compressor to the expansion valve via the radiator and a low-pressure path section extending from the expansion valve to the compressor via the evaporator, A refrigerant circulation path in which a refrigerant that can be in a supercritical state is enclosed; an inlet portion and an outlet portion of the radiator; and a refrigerant temperature detecting means that detects an intermediate portion of the refrigerant temperature positioned between the inlet portion and the outlet portion. A high-pressure side pressure estimating means for estimating the high-pressure side pressure of the refrigerant in the high-pressure path section based on the refrigerant temperatures at the inlet, outlet and intermediate parts detected by the refrigerant temperature detecting means, and a high-pressure side pressure estimating means And a control means for controlling at least one of the compressor and the expansion valve so that the high pressure side pressure of the refrigerant estimated in step 1 becomes a predetermined target high pressure side pressure.

  Further, in the invention according to claim 2, in claim 1, the intermediate portion is positioned at a portion where heat is dissipated at a predetermined ratio of the total heat dissipation amount of the refrigerant in the radiator, and the high pressure side pressure estimating means is A data table based on a Mollier diagram specific to the refrigeration cycle is provided, and the data table includes an inlet portion and an outlet portion for each of the inlet portion and the outlet portion detected by the refrigerant temperature detecting means and the intermediate portion of the refrigerant temperature. The high pressure side pressure is configured so that the enthalpy of the refrigerant, these enthalpy differences, and each enthalpy and the intermediate enthalpy of the intermediate refrigerant that has the same ratio as the predetermined ratio of heat dissipation in the intermediate part from the enthalpy difference can be referred to. The estimation means estimates the refrigerant pressure uniquely determined by the intermediate enthalpy and the refrigerant temperature of the intermediate portion as the high pressure side pressure by referring to the data table. It is characterized by a Rukoto.

Further, the invention according to claim 3 is characterized in that, in claim 2, the intermediate portion is positioned at a portion where 25% or more and 75% or less of the total heat dissipation amount of the refrigerant in the radiator is radiated.
Furthermore, the invention according to claim 4 is characterized in that, in claim 3, the intermediate portion is positioned at a plurality of parts including a part where 50% of the total heat radiation amount of the refrigerant in the radiator is radiated. .

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the refrigerant temperature detecting means measures a pipe surface temperature of a refrigerant pipe through which the refrigerant flows in the radiator, and the pipe surface temperature is measured in the radiator. It is characterized in that the temperature corrected according to the temperature of the heat radiating medium that radiates heat is used as the detected refrigerant temperature.
Furthermore, in invention of Claim 6, in any one of Claim 1 thru | or 4, a refrigerant | coolant temperature detection means measures the pipe | tube surface temperature of the to-be-radiated medium pipe | tube through which the to-be-radiated medium radiated | radiated in a heat radiator flows, The tube surface temperature is set to a detected refrigerant temperature, which is a temperature corrected according to the temperature of the heat radiating medium and the temperature to which the heat radiating medium pipe is exposed.

  According to the refrigeration apparatus of the first aspect of the present invention, the high-pressure side passage portion is estimated by estimating the high-pressure side pressure of the refrigerant in the high-pressure side passage portion based on the refrigerant temperatures of the inlet portion, the outlet portion, and the intermediate portion. Even if the pressure of the refrigerant is not detected directly, the high-pressure side pressure can be accurately estimated by taking into account the amount of heat dissipated in the radiator, in other words, the amount of heat exchange. Efficiency can be improved.

  According to the second aspect of the present invention, the high pressure side pressure estimation means includes a data table based on the Mollier diagram of the refrigeration cycle of the refrigeration apparatus, and by referring to this data table, the intermediate enthalpy and the refrigerant are intermediated. The refrigerant pressure that is uniquely determined by the temperature is estimated as the high-pressure side pressure. Thereby, in the data table, that is, the Mollier diagram, when reading the refrigerant pressure from the refrigerant temperature and the enthalpy, the intermediate enthalpy, in other words, data in the vicinity of the intermediate heat radiation amount is used. Here, generally, since the gradient of the isotherm on the Mollier diagram is horizontal near the intermediate heat dissipation level and becomes horizontal, the refrigerant pressure can be accurately read from the refrigerant temperature and enthalpy, and the high pressure side pressure is estimated. Is generally a sensitive area, the use of data in the vicinity of the intermediate heat release allows the high-pressure side pressure to be estimated more accurately and further improves the operating efficiency of the refrigeration system. it can.

Specifically, according to the invention described in claim 3, the intermediate portion is positioned at a portion where 25% or more and 75% or less of the total heat dissipation amount of the refrigerant in the radiator is radiated, thereby estimating the high pressure side pressure. In this case, it is possible to reliably use an area with high sensitivity.
More preferably, according to the invention of claim 4, the intermediate portion is positioned at a plurality of parts including a part that radiates 50% of the total heat release amount of the refrigerant in the radiator. Since the pressure reliability can be increased, the operating efficiency of the refrigeration apparatus can be improved more reliably.

  According to the invention described in claim 5, the refrigerant temperature detecting means measures the pipe surface temperature of the refrigerant pipe through which the refrigerant flows in the radiator, and the surface temperature is the temperature of the radiated medium that radiates heat in the radiator. By making the temperature corrected according to the detected refrigerant temperature, particularly the refrigerant temperature detection at the intermediate portion can be simplified, the operation efficiency of the refrigeration apparatus can be further simplified.

  Furthermore, according to the invention described in claim 6, the refrigerant temperature detecting means measures the surface temperature of the radiated medium pipe through which the radiated medium to be radiated in the radiator flows, and the surface temperature is determined as the temperature of the radiated medium. In this case, the refrigerant temperature detection at the intermediate portion can be simplified with high accuracy, and the refrigeration apparatus can be easily simplified. Operation efficiency can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a refrigeration apparatus 1 incorporated into, for example, an air conditioning system of a vehicle. The refrigeration apparatus 1 includes a refrigerant circulation path 2, and can enter a supercritical state in the refrigerant circulation path 2, for example, CO _2. A gas refrigerant is enclosed, and a compressor 4, a gas cooler (heat radiator) 6, an expansion valve 8 and an evaporator 10 are sequentially inserted. In the refrigerant circulation path 2, the part from the compressor 4 through the gas cooler 6 to the expansion valve 8 is the high-pressure path part 2 a of the refrigerant circulation path 2, and the part from the expansion valve 8 to the compressor 4 through the evaporator 10 is The low-pressure path portion 2b of the refrigerant circulation path 2 is configured.

  As shown in the enlarged cross-sectional view of the main part of the gas cooler 6 in FIG. 2, air in the vehicle compartment is blown to the refrigerant pipe 12 through which the refrigerant flows in the gas cooler 6 by a blower (not shown), and the refrigerant and blown air flowing through the refrigerant pipe 12. The passenger compartment is air-conditioned by heat exchange with the vehicle. The thermistors (refrigerant temperature detection means) 20, 22, respectively are provided on the pipe surfaces 12 a of the inlet part 14 and the outlet part 16 of the refrigerant pipe 12 and the intermediate part 18 positioned between the inlet part 14 and the outlet part 16. 24 is affixed with aluminum tape or the like, and these thermistors 20, 22, and 24 indirectly measure the inlet and outlet of the refrigerant flowing through the respective parts 14, 16, and 18 and intermediate temperatures Ti, To, and Tm.

  Each thermistor 20, 22, 24 is electrically connected to a control unit (high pressure side pressure estimating means, control means) 26 of the refrigeration apparatus 1 together with a drive unit (not shown) of the compressor 4 and the expansion valve 8. The unit 26 estimates the high-pressure side pressure Pd of the refrigerant in the high-pressure path portion 2a based on the refrigerant temperatures Ti, To, Tm, and the estimated high-pressure side pressure Pd is set to a predetermined target high-pressure side pressure Pds in the refrigeration apparatus 1. Therefore, the rotational speed of the compressor 4 and the opening degree of the expansion valve 8 are controlled as much as possible.

As shown in FIG. 3, the control unit 26 stores a data table 28 formed in advance based on a later-described Mollier diagram (FIG. 4) unique to the refrigeration cycle of the refrigeration apparatus 1.
The data table 28 uses the enthalpy data on the isotherm of the Mollier diagram, and for each refrigerant temperature Ti, To, Tm, the inlet enthalpy Hi of the inlet section 14, the outlet enthalpy Ho of the outlet section 16, and these enthalpies. The difference ΔH can be referred to, and the intermediate enthalpy Hm of the intermediate portion 18 and the high-pressure side pressure Pd can be estimated from the enthalpy data of Hi, Ho, and ΔH.

  Specifically, the intermediate portion 18 is positioned at a portion where heat is released at a predetermined ratio (heat release amount Q / 2) of 50% of the total heat release amount Q of the refrigerant in the gas cooler 6, and this position is heat exchange in the gas cooler 6. It is determined in advance by an experiment such as simulation. In the data table 28, the intermediate enthalpy Hm (= Ho + ΔH /) which is the same ratio as the ratio 50% of the intermediate heat release amount Q / 2 to the total heat release amount Q in the intermediate portion 18 from the inlet and outlet enthalpies Hi, Ho and the enthalpy difference ΔH. 2) is calculated.

  Specifically, when the thermistors 20 and 22 detect that the inlet temperature Ti that is the refrigerant temperature of the inlet portion 14 is 90 ° C. and the outlet temperature To that is the refrigerant temperature of the outlet portion 16 is 20 ° C., the data table 28 is stored. Of the plurality of tables, a table in which data of Ti = 90 ° C. and To = 20 ° C. is referenced, and the thermistor 24 detects that the intermediate temperature Tm, which is the refrigerant temperature of the intermediate portion 18, is 46 ° C. Suppose that In this case, it is estimated from the data table 28 that the inlet enthalpy Hi is 485 kJ / kg, the outlet enthalpy Ho is 240 kJ / kg, the intermediate enthalpy Hm is 363 kJ / kg, and the high-pressure side pressure Pd is 10 mPa. That is, if the refrigerant temperatures Ti, To, and Tm are detected, the detected intermediate temperature Tm is determined as long as the intermediate portion 18 is positioned at a position where the heat dissipation amount Q / 2 is radiated by referring to the data table 28. The refrigerant pressure P that is uniquely determined by the calculated intermediate enthalpy Hm is estimated as the high-pressure side pressure Pd.

  This is also apparent from the Mollier diagram showing the refrigeration cycle of the refrigeration apparatus 1 which is the reference of the data table 28 in FIG. 4. With reference to this diagram, the heat release amount of the gas cooler 6 in the intermediate section 18 is intermediate. It can be seen that in the region where the heat quantity Q / 2, that is, the enthalpy H of the refrigerant becomes the intermediate enthalpy Hm, there are many portions where the inclination of the isotherm on the Mollier diagram is almost zero and horizontal. As a result, in the vicinity of the intermediate enthalpy Hm, each piece of data in this part is interpolated and used, so that the refrigerant pressure P can be read with high accuracy and the high pressure side pressure Pd is estimated with a sensitive area. It has become.

  Here, in FIG. 4, circles indicate the refrigerant state of the inlet portion 14, triangles indicate the outlet portion 16, and black circles indicate the refrigerant state of the intermediate portion 18. As in the example of FIG. In addition to positioning the intermediate portion 18 at the part that becomes / 2, as shown in FIG. 4, the parts that become the intermediate heat dissipation quantity Q / 4 and 3Q / 4 where 25% and 75% of the total heat release quantity Q are released The intermediate portion 18 and thus the thermistor 24 may be provided in a total of three locations, and a total of five enthalpy data for each pressure P may be posted in the data table 28.

In addition, the sensitivity of the estimation of the high-pressure side pressure Pd is not limited to this by positioning the intermediate portion 18 and thus the thermistor 24 in a portion where only 25% or more and 75% or less of the total heat dissipation amount Q is radiated. It is preferable that a good area can be used.
Further, in this embodiment, the temperature of the tube surface 12a measured by the thermistors 20, 22, and 24 is corrected by the control unit 26 according to the outside air temperature including the temperature of the blown air to which the refrigerant tube 22 is exposed. The corrected data is used as the detection result of each refrigerant temperature Ti, To, Tm.

  For example, even if Tm = 48 ° C. is actually measured by the thermistor 24, for example, Tm = 50 in order to approximate the actual refrigerant temperature by correcting the temperature drop due to the heat insulating effect of the refrigerant pipe 12. The value is corrected to ° C., and this value is used by the control unit 26 as the detection result of the intermediate temperature Tm. The correction coefficient related to this correction is determined in advance by experiments such as adiabatic simulation in the gas cooler 6.

When the high pressure side pressure Pd estimated in this way is smaller than the target high pressure side pressure Pds, the control unit 26 increases the rotational speed of the compressor 4, for example, while the high pressure side pressure Pd is the target high pressure side pressure Pd. If it is greater than Pds, the refrigeration apparatus 1 is operated at the optimum actual high-pressure side pressure Pdr by decreasing the rotational speed of the compressor 4.
As described above, in the present embodiment, the high pressure side pressure Pd of the refrigerant in the high pressure side path portion 2a is estimated based on the refrigerant temperatures Ti, To, Tm of the inlet portion 14, the outlet portion 16, and the intermediate portion 18. Thus, the high pressure side pressure Pd can be accurately estimated by taking into consideration the amount of heat that changes in the gas cooler 6, in other words, the heat exchange amount, without directly detecting the pressure of the refrigerant in the high pressure side passage portion 2a. Thus, the operation efficiency of the refrigeration apparatus 1 can be improved in a simple manner.

  Specifically, by referring to the data table 28 based on the Mollier diagram showing the refrigeration cycle of the refrigeration apparatus 1, the refrigerant pressure P that is uniquely determined by the intermediate enthalpy Hm and the intermediate temperature Tm is estimated as the high pressure side pressure Pd. . Thereby, in the data table 28, that is, the Mollier diagram, regarding the estimation of the high pressure side pressure Pd, it is possible to use a sensitive region where the slope of the isotherm on the Mollier diagram is almost zero and horizontal, and the high pressure side Since the pressure Pd can be estimated with higher accuracy, the operating efficiency of the refrigeration apparatus 1 can be further improved.

Specifically, the intermediate portion 18 is positioned in a portion where 25 to 75% of the total heat dissipation amount Q of the refrigerant in the gas cooler 6 is radiated, so that the high pressure side pressure Pd is reliably sensitive. Can be used.
More preferably, the reliability of the estimated high-pressure side pressure Pd is improved by positioning the intermediate portion 18 at a plurality of locations including a location where 50% of the total heat dissipation amount Q of the refrigerant in the gas cooler 6 is released. Therefore, the operating efficiency of the refrigeration apparatus 1 can be further reliably improved.

  Each thermistor 20, 22, 24 measures the tube surface temperature of the refrigerant tube 12 through which the refrigerant flows in the gas cooler 6, and corrects the tube surface temperature according to the temperature of the blown air that radiates heat in the gas cooler 6. By using the detected refrigerant temperatures Ti, To, and Tm, in particular, the refrigerant temperature detection of the intermediate portion 18 can be simplified, so that the operation efficiency of the refrigeration apparatus 1 can be further simplified.

The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the refrigeration apparatus 1 is incorporated into an air conditioning system of a vehicle, but may be incorporated into a domestic hot water supply system as shown in FIG. In this case, the thermistor 24 is attached to the pipe surface 30a of the hot water supply pipe (heat radiating medium pipe) 30 through which water to be radiated in the gas cooler 6 flows, and the temperature of the pipe surface 30a is measured. The temperature corrected according to the water temperature flowing through 18 and the outside air temperature to which the hot water supply pipe 30 is exposed is used as the intermediate temperature Tm. Accordingly, in this case as well, the refrigerant temperature detection of the intermediate portion 18 can be simplified with high accuracy as described above, and the operation efficiency of the refrigeration apparatus 1 can be improved easily.

It is the schematic diagram which showed schematically the freezing apparatus which concerns on one Embodiment of this invention. It is the figure which showed the principal part sectional drawing of the gas cooler of FIG. 1, and the control unit which controls a freezing apparatus. It is the figure which showed the data table stored in the control unit of FIG. It is the Mollier diagram which showed the refrigerating cycle of the freezing apparatus used as the reference | standard of the data table of FIG. It is principal part sectional drawing which showed the modification of the gas cooler of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerating device 2 Refrigerant circulation path 2a High pressure path part 2b Low pressure path part 4 Compressor 6 Gas cooler (heat radiator)
DESCRIPTION OF SYMBOLS 8 Expansion valve 10 Evaporator 12 Refrigerant pipe 14 Inlet part 16 Outlet part 18 Intermediate | middle part 20, 22, 24 Thermistor (refrigerant temperature detection means)
26 Control unit (high pressure side pressure estimation means, control means)
28 Data table 30 Hot water supply pipe (heat radiating medium pipe)

Claims (6)

A refrigerant circulation path having a high-pressure path section extending from the compressor to the expansion valve via the radiator and a low-pressure path section extending from the expansion valve to the compressor via the evaporator and filled with a refrigerant that can be in a supercritical state;
Refrigerant temperature detection means for detecting the refrigerant temperature of the inlet portion and the outlet portion of the radiator, and an intermediate portion positioned between the inlet portion and the outlet portion;
High-pressure side pressure estimating means for estimating a high-pressure side pressure of the refrigerant in the high-pressure path section based on the refrigerant temperatures of the inlet portion, the outlet portion, and the intermediate portion detected by the refrigerant temperature detecting means;
Control means for controlling at least one of the compressor and the expansion valve so that the high pressure side pressure of the refrigerant estimated by the high pressure side pressure estimating means becomes a predetermined target high pressure side pressure. Refrigeration equipment. The intermediate portion is positioned at a portion where heat is released at a predetermined ratio of the total heat dissipation amount of the refrigerant in the radiator,
The high pressure side pressure estimation means includes a data table based on a Mollier diagram specific to the refrigeration cycle of the refrigeration apparatus,
The data table includes the enthalpy of the refrigerant at the inlet and the outlet and the enthalpy of the refrigerant for each of the refrigerant temperatures at the inlet, the outlet, and the intermediate detected by the refrigerant temperature detecting means. It is configured to be able to refer to the difference and the intermediate enthalpy of the refrigerant in the intermediate portion that has the same ratio as the predetermined ratio of heat dissipation in the intermediate portion from each enthalpy and the enthalpy difference,
2. The high pressure side pressure estimating means estimates a refrigerant pressure uniquely determined by the intermediate enthalpy and the refrigerant temperature of the intermediate portion as the high pressure side pressure by referring to the data table. The refrigeration apparatus described in 1.   The refrigeration apparatus according to claim 2, wherein the intermediate portion is positioned at a portion where heat is radiated in an amount of 25% to 75% of the total heat dissipation amount of the refrigerant in the radiator.   The refrigeration apparatus according to claim 3, wherein the intermediate portion is positioned at a plurality of portions including a portion where 50% of the total heat dissipation amount of the refrigerant in the radiator is radiated.   The refrigerant temperature detecting means measures a pipe surface temperature of a refrigerant pipe through which the refrigerant flows in the radiator, and detects a temperature obtained by correcting the pipe surface temperature according to a temperature of a radiated medium that radiates heat in the radiator. The refrigeration apparatus according to any one of claims 1 to 4, wherein the refrigerant temperature is set to the above-described temperature.   The refrigerant temperature detecting means measures a tube surface temperature of a radiated medium tube through which a radiated medium to be radiated in the radiator flows, and the tube surface temperature is determined based on the temperature of the radiated medium and the radiated medium tube. The refrigeration apparatus according to any one of claims 1 to 4, wherein a temperature corrected according to an exposure temperature is set as the detected refrigerant temperature.

Images