METHOD FOR OPERATING A CHILLER AND CORRESPONDING CHILLER

Abstract

 In the present invention, a chiller includes a pull-down procedure or pull-down mode, a sustain procedure or sustain mode and, additionally, a heat-up procedure or heat-up mode or temper mode.
This allows the chiller to deliberately and determined heat up content if the starting temperature of the content is below the target temperature for serving the content.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for operating a chiller, more particularly a beverage and wine chiller, even more particularly a beverage and wine chiller with an additional temper mode.

BACKGROUND ART

[0002] In the prior art a normal beverage chiller such as model W300 from Safran works in a pull-down mode or process. The state of the art mode or process is described, for example, in the document US 5802863A.

[0003] Regarding such a pull-down process, in the state of the art it has to be considered that the temperatures of the content are known and correctly identified beforehand by a separate external identification step.

[0004] The chiller in the state of the art cools down the cavity air of the chiller as low as possible with full refrigeration system performance as long as needed to allow the content to reach a target temperature. In case of US 5802863A heat load identification is used. Hereby, a plurality of stored cooldown models are used as references for bringing wine bottles to a target temperature without damage to the wine. Then, the status of the thermal load effected by the bottle temperature and amount of bottles is determined. Finally, the wine temperature is lowered in a maximized but controlled manner.

[0005] The characteristic temperatures for the process could for example be:
With an assumed content start temperature of 21 °C a realistic pull-down time could be 40 minutes in order to pull down the content to a target temperature of 8°C (cf. Fig. 4).

[0006] Assuming a perfectly controlled process, the chiller will pull down chilled air to negative Celsius air temperatures and after 40 minutes stop the pull-down operation and control the chilled air temperature in the chiller at a target temperature of, for example, 8°C in a sustain mode (cf. Fig. 4). Assuming the pull-down time is proper the bottles will also have 8°C temperature as the chilled air.

PROBLEMS ASSOCIATED WITH THE PRIOR ART

[0007] The current chillers of the state of the art are all designed only for the main function of cooling down content.

[0008] In particular for wine, more specific for red wine that has to be served at temperatures between I3°C and 18°C and depending on the type of wine, there may be the need to heat up the bottles.

[0009] The current beverage and/or wine chillers are offering corresponding sustain temperatures but do only have cool down modes that are sufficiently adequate if the content starting temperature is above the target temperature. Hence, there is a need for a pull-down process.

[0010] It may, however, be the case that there is a big logistic facility at an airport where the whole volume of a trolley with its whole content bound to be put up on a flight is cooled down in a cooling room. In this case all content, such as duty-free content as well as beverage content, is stored at 4°C together with the food trolley as this simplifies the logistics.

[0011] Therefore, for example, for red wine bottles a heat up mode is needed instead of a pull-down mode. It is not sufficient to only have a sustain or target temperature mode.

[0012] When the content placed in a wine chiller of the state of the art has a lower temperature than the target temperatures there are two scenarios possible.

[0013] In a worst-case scenario the chiller is not able to identify that the content temperature is below the target temperature and the chiller will start a pull-down mode. Assuming a target temperature for a red wine is 16°C and the bottles are at a temperature of 4°C when placed in the chiller. Then, in a chiller of the state of the art, a pull-down process will result in a bottle temperature reduction and in a worst-case scenario could lead to frozen wine bottles (cf. Fig. 5).

[0014] After the pull-down process, the chiller in the state of the art will go into a sustain mode controlling the cavity air temperature at the target temperature and the wine bottles will start to become warmer slowly by the slowly and passively increasing ambient temperature in the cavity as shown in the graph of Fig. 5.

[0015] This situation could be understood as a worst-case scenario for content having a temperature below the target temperature when being entered into the chiller and the chiller not recognizing that the temperature of the content is different from and lower than the temperature of the ambient air.

[0016] In a best case scenario, the chiller in the state of the art is able to identify that there is no cooling down necessary or that the bottle temperatures are below the target temperature and will go directly into a sustain mode without a pull-down process as shown in Fig. 6.

[0017] In this situation, which could be understood as a best-case scenario in the prior art (cf. Fig. 6), and assuming the chiller is able to identify the correct content temperature, there would be the following situation:

Assuming the content is red wine bottles that are coming from a chilled trolley with a temperature of 4°C and a bottle temperature target being 16°C,

and assuming the chiller knows the temperature of the content, a pull down is not needed and not started and the chiller immediately enters into a sustain mode controlling the return temperature at target conditions, i. e. a target temperature. The bottles will slowly, gradually, and constantly become warmer and their temperature will slowly approach the target temperature of the sustain mode, which could be 16°C as shown in Fig. 6 but it will take a long time with a low temperature gradient to even come close to the target temperature because the temperature difference will be low during the whole time of the sustain mode. Said sustain mode does not allow the bottles to become warm properly. Basically, the bottles will never really reach the target temperature or only after a very long time, which is unsuitable for the purpose within a chiller.

[0018] Considering that current beverage chillers and wine chillers do not have a dedicated heating up procedure, they are not able to heat up the content to a target temperature at the necessary rate and speed - regardless of the fact that the content temperature may or may not be known.

SUMMARY OF THE INVENTION

[0019] The invention as provided in claim 1 and claim 2 solves the above-mentioned problems of the prior art. Preferred embodiments are presented in the dependent claims.

TECHNICAL SOLUTIONS AND ADVANTAGEOUS EFFECTS OF THE INVENTION

[0020] A beverage and wine chiller normally has three functions:

a. Freezer

b. Refrigerator

c. Beverage Chiller

[0021] The beverage chiller function includes a function to provide for the target temperature range for wine. That is why the temperature range for the chiller mode normally has a temperature range from 7°C up to 18°C. This is related to the fact that the wine serving temperature varies with the type of wine, in particular being low for sparkling and white wine and higher for red wines as shown in Fig. 1 for some exemplary wines.

[0022] The basic functionality of a chiller offers a fast pull-down function to get the content in the cavity of the chiller as quickly as possible to its serving temperature or target temperature.

[0023] This will work for all content if the content is delivered with high temperature, which is above the serving temperature or target temperature, by a catering service.

[0024] Sometimes however, because of logistics the content could come from a catering service with the same uniform refrigeration system temperature for all content, typically with a temperature of 4°C. In this case, a fast pull down is not needed for all content, but a fast heating up for some content such as wine and, in particular, red wine, would be the needed procedure.

[0025] This necessary function is not provided in current beverage chillers of the state of the art.

[0026] It is one aspect of the present invention to implement an additional heating up or temper mode or process in the chiller of the present invention to achieve the necessary functions.

[0027] The basic idea of a temper mode in addition to a pulling down mode or chill mode is to have a chiller of the present invention that is able to identify the content temperature and is able to cool down with maximal performance, sustain with maximal performance and also heat up the content with maximal performance, thus bringing it as fast as possible to serving temperature or target temperature.

SOLUTION

[0028] The chiller of the present invention is able to determine the content temperature. This should be done with the available internal temperature sensors and could be done with the following procedures.

[0029] Hereby, the content temperature during the cooling and/or heating process can be measured.

[0030] Based on a heat load calculation that includes 1) the heat transfer between the bottles and the air, 2) the heat load heating up or cooling down the air and 3) the heat load cooling down or heating up the bottles. In a simplified view, considering a balanced process, in a defined time interval, the heat load for all three processes is the same and this can be used to estimate the current temperature of the bottles or other content.

[0031] The heat load 2) can be calculated based on the known air flow and measured chilled air temperatures supply and return. To achieve a higher accuracy, the air flow can also be measured.

[0032] At the same time, the speed of cooling down can be used to estimate the current heat load of the content and can be used to estimate the number of bottles inside the chiller compartment considering that it will need more time to cool down or heat up more bottles.

[0033] In the same manner if the heat load calculated is negative or positive will indicate that the temperature difference between bottles and air is positive or negative.

[0034] All these parameters will be used to estimate the content or bottle temperature and will be used in the same manner to monitor the content temperature during the pull down or heat up process.

[0035] With this content temperature monitoring, the pull down or heat up process will be started if needed and also be stopped when the content reaches the target temperature. The final monitoring parameters can be defined based on preliminary empiric and statistical data and could also be automatically optimized during operation by storage operation data.

[0036] The process will be based on measurements and statistical values and will also be influenced by the current chiller start conditions, e. g. if the chiller has just started or is running already, ambient temperatures and number of bottles inside the chiller compartment.

[0037] In addition, in order to increase the accuracy, the ambient temperature could also be included in the monitoring considering that a part of the transferred heat will be lost to the environment.

[0038] With the heat load and temperature monitoring process the chiller of the present invention will be able to change automatically from cooling down to heating up depending on the need for the respective content. The operator only has to place the content and select the target temperature.

[0039] Independent therefrom it makes sense to offer an optional preselection mode for the operator considering the heating up or cooling down process which will be faster if started in the correct mode. If the operator knows that the bottles have to be heated up this mode can be preselected and if the bottles need to be cooled down this mode can be preselected. Independent of this preselection the monitoring can change to the correct mode based on the target temperature.

[0040] The starting mode could also be predefined based on the target temperature, leading to requiring heating up for high target temperatures and cooling down for low target temperatures.

[0041] In the same manner it makes sense to offer a dedicated temper mode for wine in addition to the known rapid chill mode. The chill mode can cool down the bottles with lower air temperatures and using the temperature monitoring only to be able to identify the pull-down end. The dedicated temper mode can be defined in a more careful way, with the pull-down mode avoiding very low air temperatures to also avoid damaging the wine.

[0042] Basically, the chiller of the present invention will introduce a new mode that can be called "temper mode" or "wine temper mode". The term "temper" means that this mode is "tempering" the wine to the target serving temperature as fast as possible and in a proper manner to avoid damage of the wine from heating up and/or cooling down depending on the wine start temperature. This temper mode can be exclusive or in addition to one or more other known cooling modes. In particular, for aircraft applications this mode can be combined to the current freeze, chill and refrigerate modes.

[0043] Eventually, the chiller can offer four basic operating modes:

TEMPER:	smart and proper for fast cool down and heat up of the wine
RAPID CHILL:	smart fast beverage pull-down
REFRIGERATE:	food refrigerator mode
FREEZE:	food freezer mode

[0044] Thus, the chiller of the present invention could also be referred to as "improved or advanced chiller" or "temper" or "improved or advanced temper" instead of merely "chiller" considering it is able to cool down and heat up content.

[0045] It is one advantage of the chiller of the present invention that above explained temperature calculation does not need any additional sensors but by using the same sensors which are already present.

[0046] Another option that could be included in all presented embodiments in addition to all other mentioned options is the use of at least one additional infrared optical sensor device, that could for example be placed on the top of the cavity measuring the bottle temperature and monitoring start and end of pull down or heating up.

[0047] Another option that could be included in all presented embodiments in addition to all other mentioned options is the use of at least one external content temperature sensor at the outside of the chiller.

[0048] This option includes placing an external sensor at the outside of the chiller and could be used by an operator to place the content in front of said sensor and identify the content temperature before the content is placed in the chiller.

[0049] This sensor could also be used to identify the temperature of the content after removing the content from the cavity of the chiller.

[0050] Another option that could be included in all presented embodiments in addition to all other mentioned options is to allow the operator to choose the needed process.

[0051] Here, the operator could be asked if the content needs to be heated up or cooled down. In this case, the chiller only needs to identify the temperature and define the proper pull down, sustain or heat up features based on the target temperature.

[0052] In the present invention, the chiller includes a pull-down procedure or pull-down mode, a sustain procedure or sustain mode and, additionally, a heat-up procedure or heat-up mode or temper mode.

[0053] It is normal in the state of the art that a chiller cools down air in the cavity below the target temperature to achieve a fast pull-down time (cf. Fig. 2). This pull-down mode is also present in the present invention. Fig. 2 shows an exemplary pull-down mode where the starting temperature of the content is 21°C and the target temperature is 8°C. In the present invention, in addition, there is the case that for the heating up procedure where the chiller heats up the air well above the target temperature to achieve a fast heat up phase and only after that the chiller switches to a sustain mode controlling the cavity air temperature at the target temperature (cf. Fig. 3). Fig. 3 shows an example for a heating-up mode according to the present invention. In this example, the starting temperature of the content is 4°C and the target temperature is 16°C.

[0054] Hereby, the chiller can use an evaporator as super-heated gas and/or as air heater.

[0055] The chiller will use the same procedure used to control the chilled air temperature during sustain mode without additional components to heat up the evaporator coil, similar to the defrost procedure but with running of the evaporator fan. The super-heated refrigerant gas will be bypassed from the condenser coil trough a stepper valve, thereby heating up the evaporator coil. The hole thermodynamic cycle will operate at super-heated gas conditions. The expansion valve will still control the outlet avoiding that the liquid refrigerant reaches the compressor and blocking the liquid coming from the condenser coil. The condenser will work as liquid refrigerant accumulator, considering that the condenser will still condense the refrigerant (cf. Fig. 11 and its description below).

[0056] Another option that could be included in all presented embodiments in addition to all other mentioned options is the use of a solenoid valve to fully close the liquid line during heating.

[0057] This option could be implemented for improved safety issues related to the liquid going to the compressor (cf. Fig. 12 and its description below).

[0058] Another option that could be included in all presented embodiments in addition to all other mentioned options is the use of at least one additional low-pressure sensor and/or temperature sensor on the suction line (cf. Fig. 13 and its description below).

[0059] In combination with at least one electronic expansion valve this will be the best control option for the heating process being able to have the full control of the gas going back to the compressor (cf. Fig. 13 and its description below).

[0060] This option could be implemented for improved safety issues related to the liquid going to the compressor (cf. Fig. 13 and its description below).

[0061] Another option that could be included in all presented embodiments in addition to all other mentioned options is the use of at least one additional heater (cf. Fig. 12 and its description below).

[0062] To increase the heating up capacity at least one additional heater could be installed and operated instead of the compressor. This option could be implemented for improved safety issues in order to avoid the compressor to bypass the heater (cf. Fig. 12 and its description below).

[0063] Another option that could be included in all presented embodiments in addition to all other mentioned options is inverting the refrigeration cycle using an evaporator as condenser and as heater (cf. Fig. 16 and its description below).

[0064] Changing between chiller operation and heat pump operation is implemented in the improved chiller of the present invention. This significantly increases the heating capacity compared to the chiller of the state of the art (cf. Fig. 16 and its description below).

[0065] The present invention further comprises a method for use in a chiller comprising a pulling-down mode for cooling the content, a sustain mode for maintaining the temperature of the content at a target temperature and a heating mode for heating up the content. In addition, a TEMPER mode will be included that is able to identify if heating or cooling is needed and start the proper process.

DESCRIPTION OF THE DRAWINGS

[0066] 

Fig. 1 shows examples for sparkling and white wine and red wines and their intended serving temperatures;

Fig. 2 shows a possible example of a normal chiller in a pull-down mode with an ambient temperature of 21 °C and a target temperature of 8°C according to one embodiment of the present invention;

Fig. 3 shows a possible example of a chiller of the present invention with a temper mode with a content temperature of 4°C and a target temperature of 16°C according to one embodiment of the present invention;

Fig. 4 shows a possible example for a pull-down process in the state of the art with an ambient temperature of 21°C, a target temperature of 8°C and a pull-down time of 40 minutes in the state of the art;

Fig. 5 shows a possible example when the temperature of the content is below the target temperature and the chiller does not have this information in the state of the art;

Fig. 6 shows a possible example when the temperature of the content is below the target temperature and the chiller has this information in the state of the art.

[0067] Further, figures 7 to 16 include a better process description:

Fig. 7 shows the prior art beverage chiller hardware configuration that will be the baseline and is the best case from a cost and weight point of view.

Figs. 8 to 10 show the process used in the prior art for pull down, sustain and defrost.

Fig. 11 shows the new controlled heating up process according to the invention that in addition to a controlled pull-down process will be the main process for the temper mode

Figs. 12 to 16 show alternative embodiments of the invention.

[0068] Figures 7 to 16, respectively, show a block diagram of a chiller (top), a list of the chiller internal temperature sensors and volume flow sensors (bottom left), a refrigerant ph-diagram pressure over enthalpy (bottom middle, p refers to pressure, h refers to enthalpy), the maximal performance pressures (bottom right) and the refrigeration system processes (bottom right).

[0069] Figure 7 shows a standard state of the art beverage chiller with all main components and shows a full hermetic vapor cycle refrigeration system with: a compressor that is compressing, heating up and transporting the heated gas to the condenser, where the heated gas will be cooled down, condensed at high temperature and the liquid refrigerant will be subcooled. The subcooled liquid refrigerant will then pass the expansion valve where the liquid will be expanded reducing the temperature. The liquid refrigerant will then be evaporated at very low temperature on the evaporator and heated before the heated refrigerant gas reaches again the compressor. The function of the refrigeration cycle is to transport the heat at low temperature from the evaporator to a high temperature on the condenser. In addition, a condenser bypass valve between the compressor discharge and the liquid line where the hot refrigerant gas can go back to the evaporator without being condensed in the condenser transporting heat from the compressor back to the evaporator. A condenser air flow where the ambient air is moved by the condenser fan from the environment, passing an air filter and then through the condenser transporting the heat from the condenser out of the chiller to the environment through the exhaust air opening. A closed evaporator air flow circuit that is moved by the evaporator fan and transports the heat from the content to the evaporator coil. During the normal cooling process the evaporator air flow will be cooled down on the evaporator passing the supply temperature sensor and moved by the evaporator fan entering in the content cavity trough the supply opening. In the content cavity the evaporator air flow will circulate around the content in particular the wine or beverage bottles cooling down the content and the cavity itself. The evaporator air flow will then leave the content compartment through the return opening passing through the return temperature sensor and coming back to the evaporator. The bypass valve in combination with the supply and return temperature sensors will be used to control the temperature in the sustain mode. The bypass valve in combination with the evaporator coil temperature sensors will be periodically used for a defrost mode to be able to remove ice from the evaporator if needed. There are also provisions for overpressure control and compressor overtemperature. The standard mechanical expansion valve (TXV) shown on this configuration will control the heat gas temperature on the evaporator exit, before reaching the compressor, avoiding liquid on compressor refrigerant gas entrance.

[0070] Refrigeration cycle shown on a typical refrigerant (e. g. the old R134a, or the new R1234yf) ph-diagram (enthalpy x pressure graph) showing the heat transport at different pressures and temperatures (cf. Fig. 7).

[0071] Figure 8 shows the refrigeration system from Fig. 7 when operating with maximal performance. In the mode the bypass valve is completely closed and the hole refrigerant flow is passing through the condenser achieving the maximal performance and efficiency. This mode will always be active for maximal pull-down performance and when ambient temperature is as high needing all the cooling performance to maintain the content compartment at target temperature. In particular for the chiller freeze mode when target temperatures are down to -18°C this mode will always run at sustain mode.

[0072] Figure 9 shows the refrigeration system from Fig. 7 when operating with partial performance. This will always happen during sustain mode. Normally the compressor will run with reduced speed and the content cavity air temperature will be controlled by the return temperature and in some cases also by supply. When the temperature is below target, the bypass valve will start opening allowing a small amount of heated gas to bypass the condenser transporting some heat back to the evaporator controlling in this way the air temperature.

[0073] Figure 9 shows the refrigeration system on a refrigerant ph-diagram showing the two refrigerant cycles (p refers to pressure, h refers to enthalpy). The main refrigerant mass flow passes the condenser and goes back to the expansion valve in the liquid phase and another small mass flow passes the bypass and goes back as heated gas.

[0074] During the wine temper pull down operation, due to a carefully wine cooling down process, this mode can also be used during pull down for controlling the lowest acceptable supply temperature.

[0075] Figure 10 shows the defrost mode that will be started periodically or if ice defrost is needed. The bypass valve will be fully open in order to allow all the heated gas to bypass the condenser heating up the evaporator coil melting the ice if needed. During this very short time process the evaporator fan will be stopped avoiding to heat up the content and content cavity. A neglectable amount of refrigerant can still pass through the condenser considering the expansion valve (TXV) will not be fully closed.

[0076] Figure 10 shows only the main heated gas refrigerant flow in a ph-diagram.

[0077] Figure 11 shows the new heating up mode of the improved chiller of the present invention with a fully open bypass valve where the main refrigerant mass flow will bypass the condenser and go back to the evaporator coil that will be heated up. The evaporator fan will transport the heated cavity air coming from the hot evaporator passing the supply opening and circulating the content heating it up as fast and as long as needed to reach the defined target temperature. The cavity air will then go back to the evaporator coil through the return opening. In this configuration the content temperature prediction described in this invention will use supply and return temperature sensors for heat load and content temperature calculation.

[0078] In this case, there will be a small amount of refrigerant passing through the condenser due to the expansion valve only controlling the superheated gas temperature and not being able to fully close (not shown in Figure 11).

[0079] In particular for the heating mode during the wine temper operation, due to carefully heating up the wine, the bypass valve may be not totally open allowing more refrigerant to pass the normal way through the condenser (not shown on Figure 11).

[0080] In this configuration the content temperature described in this invention prediction will use supply and return temperature sensors for heat load and content temperature calculation.

[0081] Figure 11 shows only the main superheated gas refrigerant flow in a ph-diagram.

[0082] Figure 12 shows additional features that can be implemented in order to improve the temper mode process in combination with all other additional features described above and below.

[0083] Figure 12 shows an additional solenoid valve on the liquid line between the condenser and the expansion valve. This valve will fully close the liquid line during defrost mode and heating mode in order to provide the maximal heating performance.

[0084] Figure 12 shows an additional heater placed in the evaporator air flow. This heater can increase the heat load or be the only heating device for the heating up mode.

[0085] Figure 12 shows an additional evaporator air volume flow measurement device. Measuring the evaporator air flow will make the heat load identification for the content temperature prediction more accurate. The volume flow measurement can also be used for defrost need identification.

[0086] Figure 12 shows an additional condenser air flow measurement device. Measuring the condenser air flow in combination with the condensing temperature that can be calculated by the condensing temperature allows to estimate the chiller heat load rejection and can be used for total heat load calculations. In addition, the air flow measurement can be used to identify blocked ambient air filter.

[0087] Figure 12 shows an additional optical infrared sensor placed in the content cavity. This sensor can be used in addition to the heat load calculation or standalone be used to monitor the content temperature during pull down, heat up and cooling or heating need identification.

[0088] Figure 13 shows an alternative process for operating the thermodynamic expansion valve that can be combined with all other additional features described above and below.

[0089] Figure 13 shows an electronic expansion valve used to control the gas superheated temperature on the suction line. The advantage of the electronical expansion valve is that the valve can be fully closed and an additional solenoid valve is not needed to obtain the full heating performance during temper heating mode. In addition, a full control of the superheat temperature can be achieved and documented by the chiller controller. The electronical expansion valve (TXV) can also be used to control the chiller temperature in sustain mode and the bypass valve can stay closed.

[0090] Figure 13 shows a superheat temperature sensor and suction pressure transducers, both possibly needed to control the electronical expansion valve and can be used to document the superheated gas temperatures and optimize the temper heating process.

[0091] Figure 14 shows a heater integrated in the evaporator in combination with the electronical expansion valve that can be used for the defrost mode and the temper heating mode that can be combined with all other additional features described above and below. Considering the cavity temperature control during the sustain mode can be realized with the electronical expansion valve, the bypass valve will not be needed.

[0092] Figure 15 shows an alternative arrangement of the active chiller components and the chilled compartment with the content that can be combined with all other additional features described above and below. The chilled compartment shown in Figure 15 is not integrated in the chiller envelope but only connected with proper interfaces or proper compartment air ducting to the supply and return openings provided on the chiller envelope and open to the evaporator air flow in order to ensure that the evaporator fan is able to transport the cavity air between the evaporator coil and the compartment similar to the integrated compartment version as shown in Figure 7. The evaporator air could also be guided to more as one chilled compartment that could have additional internal air recirculation (this is not shown in Figure 15).

[0093] Figures 16a and b show a more complex alternative for a cooling heat pump concept that will make sense if the heating mode should become more important and bigger heating performance is needed that can be combined with all other additional features described above and below. The shown concept has a refrigerant flow reversing valve in order to invert the refrigerant flow transforming the condenser in an evaporator and the evaporator in a condenser. This concept may increase the complexity for the temper mode described on this invention.

[0094] In particular, the process shown on Figures 16a and 16b should be verified. It is important to know and to be able to identify the difference to the temper mode. Hereby, the air conditioning in the prior art is not connected to a closed content compartment and does not have a function to fast pull down or fast heat up the content and also does not have a content temperature prediction but only has a dedicated cooling down and sustain mode.

INDUSTRIAL APPLICABILITY

[0095] This invention can be applied in any place with electricity, for example in any kind of habitation or vehicle such as, for example, aircrafts.

[0096] This invention can be applied in structures in buildings and vehicles such as transport vehicles such as, for example, commercial aircrafts.

REFERENCE SIGNS

[0097] 

expansion valve	TXV
chilled air supply	TS
chilled air return	TR
evaporator coil inlet	TE'
evaporator coil outlet	TE"
compressor temperature	TC
condenser air inlet (ambient)	TA
condensing pressure	P2
evaporating pressure	P1
condenser volume flow sensor	VC
evaporator volume flow sensor	VE
super heat	TSH

Claims

1. A method for operating a chiller,
said chiller comprising:

a cavity for receiving a content,

a compressor,

a condenser connected to the compressor,

an evaporator connected to the compressor and the condenser, the evaporator comprising an evaporator coil,

a refrigerant,

an expansion valve (TXV) configured to expand the refrigerant,

a suction line,

a liquid line,

a bypass valve,

an evaporator fan,

a condenser fan,

a supply temperature sensor,

a return temperature sensor,

an evaporator coil temperature sensor,

a return opening passing through the return temperature sensor, and

a control device configured to operate the chiller in

a pulling-down mode for cooling the content, and

a sustain mode for maintaining the temperature of the content at a target temperature, and

a heating device,

the method comprising:

a step for conducting the pulling-down mode of the chiller for cooling the content, and a step for conducting the sustain mode for maintaining the temperature of the content at a target temperature,

a step of conducting a heating up or temper mode for deliberate determined heating up the content to the target temperature,

wherein in the heating up or temper mode the bypass valve is determinedly fully or partially opened so that the main refrigerant mass flow is configured to bypass the condenser and go back to the evaporator coil that will be heated up,

wherein the evaporator fan is configured to transport the heated cavity air coming from the hot heated evaporator passing the supply opening and circulating the content and heating the content up as fast and as long as needed to reach the defined target temperature,

wherein the cavity air then goes back to the evaporator coil through the return opening, whereby the content temperature prediction is configured to use supply and return temperature sensors for heat load and content temperature calculation,

wherein a supply temperature in the temper mode is always above the target temperature,

wherein the supply temperature in the temper mode is higher than a supply temperature in the sustain mode and at least temporarily higher than the ambient temperature,

wherein the temperature gradient in the temper mode is higher than in the sustain mode.

2. A chiller comprising:

a cavity for receiving a content,

a compressor,

a condenser connected to the compressor,

an evaporator connected to the compressor and the condenser, the evaporator comprising an evaporator coil,

a refrigerant,

an expansion valve (TXV) configured to expand the refrigerant,

a suction line,

a liquid line,

a bypass valve,

an evaporator fan,

a condenser fan,

a supply temperature sensor,

a return temperature sensor,

an evaporator coil temperature sensor,

a return opening passing through the return temperature sensor, and

a control device configured to operate the chiller in

a pulling-down mode for cooling the content, and

a sustain mode for maintaining the temperature of the content at a target temperature,

characterized in that

the chiller further comprises a heating device and

the control device is also configured to operate the chiller in a heating up or temper mode for deliberately determined heating up of the content to a desired target temperature,

wherein in the heating up or temper mode the bypass valve is determinedly fully or partially open and the evaporator fan is configured to transport the heated cavity air coming from the hot heated evaporator passing the supply opening and circulating the content in order to heat up the content in the cavity as fast and as long as needed to reach the defined target temperature, whereby the main refrigerant mass flow is configured to bypass the condenser and go back to the evaporator coil that will be heated up,

wherein the supply temperature in the temper mode is always above the target temperature,

wherein the supply temperature in the temper mode is higher than the supply temperature in the sustain mode and at least temporarily higher than the ambient temperature,

wherein the temperature gradient in the temper mode is higher than in the sustain mode,

wherein the cavity air goes back to the evaporator coil through the return opening, and

wherein the content temperature prediction is configured to use supply and return temperature sensors for heat load and content temperature calculation.

3. The method according to claim 1 or the chiller according to claim 2, wherein the chiller further comprises at least one additional sensor to measure the air temperature of the cavity during the loading process of the content.

4. The method according to claim 1 or 3 or the chiller according to claim 2 or 3, wherein the chiller further comprises at least one additional sensor to determine the content in the cavity such as, for example, infrared sensors.

5. The method according to claim 1 or 3 or the chiller according to claim 2 or 3, wherein the at least one sensor is a contactless sensor.

6. The method according to claim 1, 3, 4 or 5 or the chiller according to claim 2, 3, 4 or 5, wherein the chiller further comprises at least one temperature sensor at the outside of the chiller.

7. The method according to any of claims 1 or 3 to 6 or the chiller according to any of the claims 2 to 6, wherein the chiller further comprises a solenoid valve to fully close the liquid line during heating.

8. The method according to any of claims 1 or 3 to 7 or the chiller according to any of the claims 2 to 7, wherein the chiller further comprises at least one additional low-pressure sensor and/or temperature sensor on the suction line.

9. The method according to claim 8 or the chiller according to claim 8, wherein the chiller further comprises at least one electronical expansion valve in order to control the heating process.

10. The method according to any of claims 1 or 3 to 9 or the chiller according to any of the claims 2 to 9, wherein the chiller further comprises at least one additional heater.

11. The method according to any of claims 1 or 3 to 10 or the chiller according to any of the claims 2 to 10, wherein the chiller further comprises at least one additional evaporator air volume flow measurement device.

12. The method according to any of claims 1 or 3 to 11 or the chiller according to any of the claims 2 to 11, wherein the chiller further comprises at least one additional condenser air flow measurement device.

13. The method according to any of claims 1 or 3 to 12 or the chiller according to any of the claims 2 to 12, wherein the chiller is further configured to invert the refrigeration cycle using an evaporator as condenser and as heater.

Drawing