DK178891B1

DK178891B1 - Control system for refrigerated equipment and apparatus with advanced energy saving features

Info

Publication number: DK178891B1
Application number: DKPA201570251A
Authority: DK
Inventors: Manlio Poto; Paolo Chiaramonte; Roberto Di Tommaso
Original assignee: Dixell S R L
Priority date: 2012-10-08
Filing date: 2015-04-29
Publication date: 2017-05-01
Also published as: CN104969137B; DK201570251A1; CN104969137A; BR112015007697A2; ITMI20121677A1; WO2014057331A1

Abstract

The present invention discloses a control system to be applied to any refrigerated cabinet or any refrigerated apparatus equipped with a refrigerated storage compartment. This control system comprises an electronic controller with memory and, if necessary , including a command. interface. This control system uses one or more temperature probes and is able to build a data set by extracting the temperature variation values from said temperat ure probes. This data set is used from the control system to build an analytical model able to identify two different operating modes for the apparatus named the normal mode and the energy saving mode, where the energy saving· mode is defined as an operating period of time, for the apparatus, with a temperature higher than the temperature used during the normal mode.

Description

Control system for refrigerated equipment and apparatus with advanced energy saving features

Field of application

The hereafter invention describes a control system for refrigerated equipment arid apparatus (for drinks and not perishable foods, hereafter referred as consumer goods) where the above mentioned control system, with or without door for accessing to the refrigerated stored compartment, implements advanced energy saving features.

State of the art

Refrigerated Equipment is used worldwide because of they provide the ability to sell consumer goods at the best temperature (hereafter referred as business temperature or SETPOINT) in shops, restaurants, shopping center and so on (hereafter referred as dealers).

It is commonly known that any refrigerated equipment implements a cooling/freezing circuit where at least a compressor, an evaporator with or without fons, a condenser and an isolated/refrigerated storage compartment are used to maintain consumer goods at a temperature (called the operating SETPOINT) lower than the environmental one. This makes the consumer goods more attractive and promotes their consumption. Generally, some type of electronic or mechanical control equipment is used to maintain the operating temperature in the refrigerated equipment

Maintaining any product at a temperature lower than the temperature of the ambient environment requires large energy consumption which results in increased operating costs for the dealer. For this reason, during the last several years many energy savings concepts have been introduced in the refrigerated equipment (reducing both energy consumption and operating costs).

Note on state of the art

One of the existing solutions is to maintain the consumer goods at the operating SETPOINT only during business hours of the dealer and by using a different temperature, higher than the SETPOINT, during non-business hours.

Nowadays, the most effective techniques used to change the working temperature of the refrigerated equipment can be summarized as follows: • Manual changing of the SETPOINT: this requires the interaction of an external operator who is required to set a temperature higher than the SETPOINT just before the closing period of the dealer. This solution has the drawback that this operation (changing the SETPOINT) is not always performed and if the SETPOINT was changed and is not changed back during the first hours following the opening of the same dealer, the real temperature of the consumer goods will not be at the required SETPOINT (due to the temperature inertia related to any goods). • Automatic changing of the SETPOINT by using a clock electronic circuit. This solution requires an additional electronic circuit and it is not able to detect variations in openings and closing hours of the dealer or time . changes due to the beginning or the ending of a daylight saving time period. In case of these events, the SETPOINT settings of the refrigerated equipment must be corrected manually from an external operator. • Automatic changing of the SETPOINT by using external “use sensors” installed on the refrigerated equipment (for example door sensor, presence sensor, vibration sensor, etc.). EP 1540438 B1 discloses this technique: it is a very efficient technique because of the refrigerated equipment is able to automatically adapt the SETPOINT temperature of the goods depending on the use of the refrigerated equipment itself or changing of the opening intervals of the dealer. On the opposite way, this solution needs to install additional components on the refrigerated equipment such as door sensor, presence sensor and so on. This introduces additional costs for both raw materials and assembling time of the refrigerated equipment. • Proactively managing some predictable thermal environments of the refrigerated equipment as disclosed in the Patent US2007/0225871 A1.

This method uses a predefined set of actions which will be performed when, a specific predictor occurs. This solution has no self-adaptive capability and requires the implementation of different predictors for any different apparatus.

Another technique to reduce energy consumption is to optimize the compressor on/off cycle: its scope is to reduce the compressor on time. • Patent US2012/0059522 A1 discloses a method to optimize the compressor on/off cycles by analyzing the real and predicted pattern of use of the apparatus and by measuring the internal and external temperatures. This permits to increase energy efficiency through time, but, it requires the use of an external temperature probe, which leads to incremental complexity of the control system used and also introduces additional costs. • Patent EP 2474799 A2 discloses a method to control the temperature of the refrigerated storage compartment without using any temperature probes which is placed into the compartment itself. The temperature regulation is performed by measuring and comparing one or both signals arriving from an external temperature probe and a power supply voltage analyzer. An additional signal from a door sensor can also be used. These signals allow the creation of a pattern of operation of the refrigerated equipment which will be used to modify the compressor on/off cycles. This method is based on the assumptions of reaching a stationary behavior of the compressor as soon as the request temperature is reached. It needs to combine signals arriving from different sources and cannot guarantee an accurate temperature control nor give the possibility to display the real temperature of the refrigerated storage compartment. In addition to this, specific tests must be done to estimate the optimal pattern of operation of any different apparatus which means increasing of the complexity and also of the final costs.

Another technique used to increase the efficiency of a refrigerated equipment, and to obtain savings in both energy consumption and costs, is to optimization the defrost cycle. A defrost cycle is required to melt the ice present on the evaporator surface. In fact, the presence of ice on the evaporator surface makes the thermal exchange of the cooling circuit worse, increasing total energy consumption. The existing techniques used to optimize the defrost cycle can be summarized as follows: • Off-cycle defrosts: in this case the compressor, which is part of the cooling circuit, is stopped following a preset schedule and for a predefined interval of time. • Defrost with evaporator temperature control: a temperature probe, placed on the evaporator surface, is used to stop the running defrost cycle as soon as the measured temperature reach and goes over a preset value. A safety timer is also used to guarantee that the running defrost cycle will be stopped, in case of any malfunctioning, after elapsing this safety timer. As in the previous case, defrost cycle follow a preset schedule. • The analysis of the évaporator temperature trend measured from the evaporator probe placed on the evaporator surface: in this case the ice melting phase is detected (phase normally known as latent heating) and the heating elements are activated with pulse modulated criteria at the end of the melting phase in order to optimize the duration of the defrost cycle. Patent EP328151 B1 disclosed this method.

In the above mentioned solutions, both the ones which change the SETPOINT and the ones which optimize the defrost cycle, an integrated control system for energy saving is absent. This control system should use only the resources already present in standard refrigerated equipment and automatically optimize the energy consumption in any possible way.

The present invention addresses these needs, by combining the capability to maintain the lower SETPOINT temperature of the goods only during the business hours of a dealer, and without introducing in the refrigerated equipment any additional components normally not required for its operation. Moreover, the present invention introduces a new concept of. energy savings through an integrated management and optimization of the various sources, present in the refrigerated equipment, and responsible for the energy consumption.

Summary of the invention

The present invention is intended to be applied to any refrigerated equipment, with or without door for accessing to the refrigerated storage compartment, and make use of the already present temperature probes (both the regulation and the evaporator one) to control the temperature inside the refrigerated storage compartment and for estimating the time periods for Energy Saving Mode activation, where “Energy Saving Mode" is intended to be any working period of time for the refrigerated storage equipment with a temperature higher than the business temperature. For further information, any working period of time for the refrigerated equipment at the business temperature will be defined hereafter as “Normal Mode”.

Brief description of the drawings FIG. 1: represent a block diagram of the control system object of the. present invention is shown. Inputs, outputs and their interaction with the electronic controller are reported. See the following TABLE to find the description of the blocks present in the FIG.1.

Legend for Figure 1 Symbol Meaning A Regulation temperature probe B Evaporator temperature probe C Electronic controller q Command interface E Compressor F Evaporator fans G Defrost elements H Lights FIG.2: describes a flow chart related to the method used from the functional model of the invention object of the present patent. FIG.3: describes a flow chart related to the classification of any temperature variation measured during the functioning of the refrigerated equipment. FIG.4: describes a flow chart related to the management of the defrost cycle during any Energy Saving Mode.

Detailed description

The present invention is intended to be applied to any refrigerated equipment where the regulation of the temperature of the refrigerated storage compartment is controlled by an electronic controller. In the standard literature, the temperature régulation of a refrigerated stored compartment, part of the apparatus, is normally managed from a temperature controlling system and by monitoring one or more characteristic temperature trends, measured by one or more temperature probes. Such temperature controlling system is able to regulate the temperature of the apparatus under its control by supervising all the involved parts (compressor, evaporator, condenser, fans, see Fig.1).

The inputs of such temperature controlling system are defined as: • the control of the goods temperature by using a "regulation temperature probe" placed into the refrigerated storage compartment of the apparatus; • the control of the evaporator temperature by using an "evaporator probe" placed on the evaporator surface. This input is used for the temperature controlling system to keep high the efficiency of the heating exchange between evaporator and the air into the refrigerated stored compartment. Another use of this input, and also executed from the temperature controlling system, is to avoid ice buildup on the evaporator surface. • the control of the condenser temperature by using a condenser probe placed on the condenser surface. This input is used to keep high the efficiency of the heating exchange between the condenser and the air of the environment surrounding the appliance.

Moreover, some other functions, parts of the standard knowledge literature, can be included in the temperature controlling system: these functions could be the safety functions used to check the maximum temperature of the goods and the maximum temperature reached from the condenser or the compressor delayed activation, or other functions; someone skilled in the art will realize.

Recently, some functions related to the energy consumption optimization have been introduced. Some of them are related to the management of the defrost cycle. The current knowledge literature describing the optimization of the defrost methods can be summarized as follows: • passive method: the defrost is performed by compressor cycle off; • active method: the defrost is performed by using hot gas, also known as cycle inversion, or by using electrical heater elements.

In both the above cases, the target is to melt the ice present on the evaporator surface. A collateral effect of melting the ice will be introduced: the rising of the temperature of the refrigerated storage compartment depending from the position of the evaporator and the quantity of ice present. For this reason, the first request is to optimize the duration and the schedule of the defrost cycle in order to limit the rise of the temperature inside the refrigerated storage compartment. There are different ways to obtain this result: • use a dedicated temperature probe, the evaporator probe, in order to check the temperature on the evaporator surface and interrupt the running defrost cycle as soon as the measured temperature value goes over a preset value. This simple solution does not give the optimization of the duration and schedule of the defrost cycle because of it does not take into consideration the real amount of ice present on the evaporator surface. • Analyze the trend of the evaporator temperature curve in order to detect the ice melting phase, known as latent heating phase, and interrupt the running defrost cycle only when this melting phase is finished. This method, which works well in case of electrical defrost (active defrost method), carinot be adapted in all that cases where a passive defrost method (compressor cycle-off) is used. EP0328151 B1 discloses the state of the art method for defrost cycle. In such solution, the defrost cycle is made by using electrical heater elements which are actively driven, till the end of the latent heating phase, and pulsing till the end-defrost condition is reached. The evaporator temperature trend is analyzed at preset interval of time in order to detect the end of the latent heating phase and the end-defrost condition.

The present invention introduces an innovative way to extend the analysis of the . evaporator temperature trend also to appliances using passive defrost methods by integrating both: • a comparative analysis of the evaporator temperature trend and the regulating temperature obtained from a precise driving method of the compressor and evaporator fans. The difference between regulation and evaporator temperatures is constantly monitored in order to detect when the preset end-defrost condition is reached. • use the beginning of any “Energy Saving Mode" to start a defrost cycle. This allows the controller to take advantage of the temperature increasing, due to the change from “Normal Mode” to the “Energy Saving Mode”, and use this thermal gradient to reduce the additional request of energy, at the end of any defrost cycle, to reach the SETPOINT temperature.

Another way to obtain energy saving is by using different SET POINT depending on the working condition of the appliance under control. For example, here are some solutions from the existing state of the art: • Change the temperature SETPOINT following a preset schedule. This needs additional hardware, known as Real Time Clock, which must be set manually and depending on the dealer’s business hours. This solution does not achieve the expected results if the dealer changes its business hours or if the time change seasonally. • EP 1540438 B1 discloses a solution that permits to dynamically create arid update interval of time where different SETPOINS will be used. A plurality of signals coming from “use sensors” (e.g. door switch or vibration sensor) is used to implement a pattern of use of the appliance under control. In this way it is possible to use the required SETPOINT when some activity on the appliance is detected, and use a different temperature value, higher than the SETPOINT one, during inactivity intervals. This solution requires the use of at least one of the “use sensors”, even if these sensors lead to additional raw material and production costs for the manufacturer.

The present invention introduces the possibility of avoiding any “use sensors” but still providing the benefits of energy savings. , to the invention discloses a method of analyzing the temperature variations instead of activity signals (generated from use sensors). In this way, the production process is simplified and the final costs for the manufacturer are reduced. It is also possible to replace or refurbish in a short amount of time and in a simple way any kind of appliance (refrigerated equipment) already present in the field. Another aspect of the present invention is that it makes use of different energy saving methods and merges them into the same control system, resulting in a better performing solution.

Analytic model used to identify periods of Energy Saving

The modes of operation of a control system (Fig.1) and the object of the present invention can be distinguished between:

• “Normal Mode”: this mode of operation is identified with an interval of time where the regulation temperature for the refrigerated storage compartment is equal to the SETPOINT • “Energy Saving Mode”: this mode of operation is identified with an interval of time where the regulation temperature for the refrigerated storage compartment is higher than the SETPOINT.

The control system of the present invention makes use of an electronic controller (C of Fig.1) which provides the data collection from the available temperature .probes used in the refrigerated equipment (A, B of Fig.1). This electronic controller converts in the data collected into a data set, and then analyzes this data set. The result of the analysis is an analytical model able to automatically change the mode of operation of the refrigerated equipment by acting on the available outputs (E, F, G and H of Fig.1).

In general, a control system object of the present invention is made of: • One or more temperature probes (A, B of Fig. 1) placed in the refrigerated storage compartment and used to regulate the temperature and to detect any temperature variation. Said temperature variation, measured by the temperature probes, can be classified as follows: - Short-period variation, which is defined as an instantaneous temperature variation. It is due to any change in the balance conditions of the appliance under control. This can be due to a door opening or to any refilling operation of the refrigerated stored compartment. - Medium-period variation, which is defined as a slow temperature variation. It can be due to the thermal dispersion of the appliance under control toward the surrounding environment or following day-night temperature changing or due to seasonal temperature variations.

One of these temperature probes can be placed on the evaporator surface in order to measure the evaporator temperature and control any defrost cycle. • An electronic controller (C of Fig.1) able to collect, analyze, classify, process and store the temperature variations detected from the available temperature probes (data set processing). This electronic controller drives the available loads, where the means of “loads” is all the elements, parts of the appliance under control, which require energy, like the compressor, the fans, the lights and the heater elements of the appliance (E, F, G, H of Fig.1). From the data set processing, and by using an internal algorithm, the electronic controller is able to build an analytical model of operation. By using this model, the electronic controller is able to adapt the functioning of the apparatus to any specific case, giving the best optimization between business temperature and energy saving request. In this way, the analytical model is able to enable two different operating conditions for the apparatus: the above mentioned “Energy Saving Mode” and the “Normal Mode”. The analytical model identifies the “Normal Mode" with any interval of time where temperature variations are detected and the “Energy Saving Mode” with any interval of time where no temperature variations had been detected. When in “Energy Saving Mode”: - The SETPOINT will be moved to a value higher than the business SETPOINT and depending of a preset value. - At the beginning of any “Energy Saving mode” a defrost cycle will be performed (Fig.4). - The duration of this defrost cycle is optimized by controlling the difference between the regulation and the evaporator probe temperature (17, 18, 19 of Fig.4). By analyzing this difference, it is possible to decide the right moment to stop the running defrost. This permits to automate the defrost cycle, without any external interaction of third persons. - Having defrost cycle automated and optimized reduces the temperature rising of the temperature increase of the goods in the refrigerated storage compartment (due to the physics related to any defrost process) with less energy request to maintain the SETPOINT after finishing the running defrost.

The following paragraphs present a detailed description off the analytical model: A. After powering on (1 of Fig.2) the data storage of the electronic controller is reset. The electronic controller performs the regulation for reaching the business SETPOINT (the one used during any “Normal Mode”) and then starts the calculation of the coefficient CDS (dispersion coefficient of the appliance) by using the temperature variation analysis (3, 4, 5, 8 of Fig.2) and (Fig-3). B. During the setup phase of a new PERIOD of analysis (2 of Fig.2), and depending on the preset configuration, the electronic controller will begin a new PERIOD of analysis of predefined duration (from 1 to 20 days). Any PERIOD is divided into sub intervals of 30 min each and named CELLS. A CELL is used to collect, analyze and classify all temperature data coming from the available temperature probes (Fig.3). C. During any interval of time of 30 minutes, equivalent to a CELL (Fig.3), the algorithm stores the number of temperature variations. (VT) (14 of Fig.3) , higher than the coefficient CDS (11, 12, 13 of Fig.3). At the end of any CELL the medium coefficient of dispersion of that CELL (CDC) is updated (15 of Fig.3). D. One time a day, or any 48 CELLS, the average number of temperature variations (MVT) as the average of the last 48 stored values of VT: Then the CDS coefficient is updated (8 of Fig.2) as average of the last 48 stored CDC values. Then the algorithm classifies the CELLS, belonging to the just finished PERIOD, depending on their proper VT number: - If the VT number of the nth-CELL is higher or equal to the average value MVT (11 of Fig.2), then the nth-CELL will be classified as belonging to the “Normal Mode” (NM-CELL). - If the VT number of the nth-CELL is lower than the average value MVT (11 of Fig.2), then the nth-CELL will be classified as belonging to the "Energy Saving Mode" (ES-CELL). - The last operation of the algorithm is to create the functional model for the apparatus (11 of Fig.2) as grouping of the CELLS belonging to the same mode. A filter is used to force any ES-CELL sequence lower that a preset value (which depends on the configuration) to belong to the “Normal Mode”. E. During any new PERIOD of analysis the following steps are performed: - Operations of the here above section (B) are repeated - Operations of the here above section (C) are repeated - If the actual CELL under analysis shows to belong to a different mode (respect to the previous PERIOD), then the operating mode of this CELL is immediately changed (6, 7 of Fig.2) - Operations of the here above section (D) are repeated

The following paragraphs provide a detailed description for automatic defrost management: A. At the beginning of any “Energy Saving Mode” a new defrost cycle starts (16 of Fig.4) B. The outputs (compressor (E of Fig. 1), evaporator fans (F of Fig.1) and heating elements (G of Fig. 1)) are driven from the electronic controller according to the difference of temperature between the regulation and the evaporator temperature probes (17 of Fig.4). C. The electronic controller continuously calculates the difference of temperature between the regulation and the evaporator temperature probes. D. The electronic controller stops the running defrost cycle as soon as the here above difference of temperature reach a preset value (.19 of Fig.4). E. At the end of the running defrost cycle, the electronic controller will restart the regulation in order to reach and maintain the required SETPOINT (20 of Fig.4).

Claims

1. Styresystem egnet til et køleskab såvel som ethvert køleapparat udstyret med et køleopbevaringskammer, hvor - styresystemet er i stand til at fungere i en normal modus eller i en energisparemodus, - styresystemet omfatter en elektronisk kontroller med hukommelse og, om nødvendigt, inkluderer en kommandogrænseflade, - styresystemet inkluderer én eller flere temperaturfølere anvendt til at måle og regulere temperaturen inden i køleopbevaringskammeret, - styresystemet er i stand til at danne et datasæt ved at ekstrahere temperaturvariationsværdier fra signalerne målt af temperaturfølerne, kendetegnet ved evnen til at anvende datasættet til at skabe en analytisk model, som anvendes til at definere intervaller af drift i en normal modus eller i en energisparemodus.1. A control system suitable for a refrigerator as well as any refrigerator equipped with a refrigeration storage chamber, wherein - the control system is capable of operating in a normal mode or in an energy saving mode, - the control system comprises an electronic controller with memory and, if necessary, includes a command interface , - the control system is capable of forming a data set by extracting temperature variation values from the signals measured by the temperature sensors, characterized by the ability to use the data set to create a temperature set. analytical model used to define intervals of operation in a normal mode or in an energy saving mode.

2. System ifølge krav 1, hvor anvendelsen af den analytiske model tillader at aktivere to forskellige driftsmodusser, den normale modus, hvor temperaturvariationer detekte-res, og energisparemodussen, hvor der ikke detekteres nogen temperaturvariationer.The system of claim 1, wherein the use of the analytical model allows to activate two different operating modes, the normal mode in which temperature variations are detected, and the energy saving mode in which no temperature variations are detected.

3. System ifølge krav 2, hvor hver aktivering af energisparemodussen også aktiverer en afrimningscyklus.The system of claim 2, wherein each activation of the energy saving mode also activates a defrost cycle.

4. System ifølge krav 3, hvor én af temperaturfølerne, reguleringsføleren, anvendes til at regulere temperaturen af køleopbevaringskammeret, og hvor en anden temperaturføler placeret på fordamperoverfladen og defineret som fordamperføleren, anvendes til at styre enhver afrimningscyklus.The system of claim 3, wherein one of the temperature sensors, the control sensor, is used to control the temperature of the cooling storage chamber, and wherein another temperature sensor located on the evaporator surface and defined as the evaporator sensor is used to control any defrost cycle.

5. System ifølge krav 4, hvor afrimningscyklusafbrydelsen automatisk identificeres ved at anvende forskellen mellem reguleringsføleren og fordamperføleren.The system of claim 4, wherein the defrost cycle interruption is automatically identified by using the difference between the control sensor and the evaporator sensor.