WO2008093282A2

WO2008093282A2 - Device to monitor and register the transport and storage temperature of temperature-sensitive products and method thereof

Info

Publication number: WO2008093282A2
Application number: PCT/IB2008/050315
Authority: WO
Inventors: Jorge Manuel Gomes Barbosa; Miguel Fernando Paiva Velhote Correia; André David LEITE DE MELO; Miguel Ângelo ARAÚJO CARVALHO FERNANDES
Original assignee: Universidade Do Porto
Priority date: 2007-01-30
Filing date: 2008-01-29
Publication date: 2008-08-07
Also published as: PT103649B; WO2008093282A3; PT103649A

Abstract

The present invention relates to a method and device to monitor and register the transport and storage temperature of temperature-sensitive products (2). The developed method allows tem¬ perature measurement on the product's surface (2) through the room temperature which is acquired by a sensor (3) being recorded at the control device (5). This device has a processing unit that implements the referred method and communicates to the outside the temperature that was calculated on the surface of the product (2). The technical problem solved by the present invention consists of using the temperature on the surface of the product instead of using room temperature to determine the quality of the product, as other devices do. The product (2) must be in a controlled- temperature environment, inside a thermo container (1) capable to maintain a programmed room temperature. The room temperature suffers variations due to door openings (4) in order to access the products, which are for example removed from the thermo container (1) along a journey of a distribution process.

Description

DEVICE TO MONITOR AND REGISTER THE TRANSPORT AND STORAGE TEMPERATURE OF TEMPERATURE- SENSITIVE PRODUCTS AND METHOD THEREOF

Technical field

[1] The present invention is the answer to the need for monitoring room temperature of temperature-sensitive products, such as in the transport and storage of products in thermo containers that maintain conditioned temperature. Background Art

[2] The temperature monitoring and control is a determinant factor in quality management of temperature-sensitive products, there being the subsequent need to assure control over the cooling process along the production, storage and distribution. The bacteria which are normally present in products multiply at several rhythms according to temperature. To preserve a product correctly, the temperature conditions must be propitious to slowdown (cooled products) or stop (frozen products) the development of bacteria. For example, at -18°C, the growth of bacteria is stopped; at 5°C the bacteriological growth increases and has an optimum growth temperature at 37°C. In the presence of a deficient temperature control, the amount of microorganisms present in the products will achieve, in a few hours, dangerous levels to health. For example, with a product at 37°C, an initial colony of 100 bacteria will grow up to 800 within the first hour, 6 thousand within the second hour, 50 thousand within the third hour, 400 thousand within the fourth hour and 3 million within the fifth hour.

[3] The temperature control process of the temperature- sensitive products, such as food and medical drugs, is part of the quality management systems of companies, thereby existing systems to help such control as is described hereinafter.

[4] EP1667059A1, Information Processor and Processing Method, Information

Processing System, Information Processing Program, Recording Medium, and Vehicle', describes a system to monitor the temperature in containers used during package transportation. It has several temperature sensors along the container to measure the room temperature near the transported food. There is a register central that sends data to a server at the end of the journey, allowing the access to the temperature inside the container during transportation.

[5] IE20040761, 'Refrigeration Vehicle', presents a vehicle equipped with several room temperature sensors, door sensors, reinforced coating for the thermo container among other features. The application consists in the transport of temperature-sensitive products, such as refrigerated food and medical drugs (among 2°C and 8°C). Remarking in this patent is the possibility of including a packed sensor as if being a product in order to simulate the temperature at which the product is submitted to, also considering its package.

[6] JP2004108703, 'Operation Management Meter for Insulated Van', presents a measurement system for a transport vehicle with an isolated and cooling container, capable of recording the temperature inside the container. It is applied to food, fish and medical drugs transportation.

[7] JPl 1348647, Operation Management Device for Insulated Van, presents a real time temperature control system, similar to the previous one, but with the specificity of not needing the intervention of a worker. When the system detects that the transportation temperature is above the predefined values, it communicates the temperature data to the control center. After that, the control center will communicate an eventual problem to the driver.

[8] The several patents referred show the importance of temperature control in the transportation of temperature-sensitive products, namely food and medical drugs. The monitoring, for example, of food temperature, is of legal obligation and for this reason, both norms of International Standard Organization (ISO) 2200:2005, and Codex AIi- mentarius, that are recognized by the members of the World Trade Organization (WTO) as the guideline on which every national application of food control is evaluated, stand for using the HACCP referential, its principals and implementation steps. The HACCP referential basically implies, controlling and monitoring the cooling chain along the life cycle of temperature-sensitive products, that is, from primary production to end-user. The present invention differs from the previous ones for the fact of monitoring the products' temperature based on the temperature on their surface, instead of the described approaches that use room temperature. This last one does not translate by itself the thermal variations in the products, which are considerably slower than the variations in room temperature, which suffers significant variations when the door of a container with conditioned atmosphere is opened (either in transport or storage). The use of the surface temperature of the products allows more objectivity and precision on the evaluation of their preservation level. This is obtained by the implementation of a calculus method that estimates the temperature on the product's surface based on room temperature. Summary of the invention and advantages thereof

[9] The present invention is composed of a method and a compact programmable and independent device, which is equipped to measure, record and process the value of room temperature in cooling containers. The method and device allow monitoring the surface temperature of an object within a certain period, according to a calculus method that uses the initial surface temperature and the room temperature as basis; the device is non-invasive, that is, there is no contact between the device and the object to monitor during the process.

[10] The compact, programmable and independent device is an electronic circuit that periodically acquires the value of the room temperature, processes it and communicates the temperature of the product's surface. The measurement means is, for example, a signal conditioning circuit for the temperature sensor. The register means is, for example, a non- volatile memory. The processing means is, for example, a microprocessor or microcontroller. The cooling containers referred are, for example, transporting vehicles equipped with cooling containers used in the distribution process, or fixed refrigerators used to store products.

[11] The compact, programmable and independent device has a battery system in order to keep a continuous operation even when the main power supply is turned off, such as an energy cut off that occurs when the motor of the distribution vehicle is turned off.

[12] The processed data that represent the temperature of the products' surface, as well as the room temperature can be transferred to a computing system, such as a personal computer, a mobile phone, a printer and a PDA, among others.

[13] According to the present invention, the products' temperature control can be rigorously and trustfully made at low cost, since it does not require a change in the existing infrastructures and allows keeping the records during the products' lifetime. Brief description of drawings

[14] Figure 1 shows the necessary elements to use the invention, which are integrated in the quality control of temperature- sensitive products.

[15] Figure 2 shows a block diagram as an example of the components that integrate the control device referred in figure 1.

[16] Figure 3 is a representative diagram of system components and the way they are connected to each other.

[17] Figure 4 is a flowchart explaining the basic structure of the control program.

[18] Figure 5 is a flowchart explaining the acquisition and processing of the room temperature values.

[19] Figure 6 is a flowchart that explains the event processing that is created by the system user.

[20] Figure 7 shows the representative graphic of the thermo behavior of the sample considered in the example described. Detailed description of the invention

[21] With reference to the drawings, one way to exemplify the invention is hereinafter described. Nevertheless, the content of this invention is not limited to this explanation.

[22] Figure 1 shows the necessary elements to use the invention, which is integrated in the quality control of temperature-sensitive products. The control device (5) is placed on the outside of the cooling container (1). In the case of a transport vehicle, used in the products' distribution, the placement of the device (5) is carried out in the cabin of the vehicle.

[23] The cooling container (1) must have the capacity to maintain a certain reference temperature, for example, between 0⁰C and 4°C in transporting refrigerated products. It has an access door to the inside, so that when the door is opened, changes in the room temperature of the container (1) occur. When the door is closed, the cooling equipment (not shown) of the container (1) restores the reference temperature.

[24] The control device (5) receives the signal from the temperature's sensor (3) and displays the room temperature inside the cooling container (1). The temperature sensor

(3) can be placed anywhere inside the container (1), preferably next to the access door

(4) because it is the area that suffers highest temperature variation when the door is opened to deliver the products, showing therefore the worst case.

[25] When called by the operator, the control device (5) communicates the room temperature readings and the temperature calculated on the products' surface to a wireless mobile computing system (6), such as a mobile phone, a PDA, a personal computer or printer. It is possible to do wireless and serial communication with an interface device (7) comprising a computational information system. This device has the purpose to allow data collection at the end of the distribution journey or, in the case of a fixed cooling installation, it allows using the data continuously collected of room temperature and products.

[26] The receiving device (8) appears in the distribution situation and represents the computational equipment of the products' recipient, capable of receiving through wireless communication the data related to the product's temperature during transportation. The receiving device (8) may be, for example, a mobile phone, a PDA, a personal computer among others. Using the device (8) is not an obligation to the present invention, and the data related to the products' temperature can be delivered by other means, such as printed paper, email, among others.

[27] Figure 2 shows a block diagram, as an example of the control device (5) components.

The communication module (25) allows the communication of the temperature values to the interface device (7) and to the receiving device (6). The serial communication can be, for example, RS232c, USB among others. The wireless communication may be, for example, Bluetooth, Ethernet IEEE 802.1 lb/g, among others. The communication module (25) allows transferring data in an efficient and practical way among the several agents evolved in a storing or distribution process.

[28] The non- volatile memory module (24) can be, for example, a hard disk, a Flash memory, among others, and it has the task of storing the values read of the room tern- perature. The values of the temperature on the products' surface can also be stored in this memory (24) or can be recalculated whenever necessary. The memory module (24) can be configured to save a program, its initial values at several levels, according to the requirements.

[29] The acquisition module (27) measures the room temperature in sample intervals defined in the program that is executed in the processing module (28). The solution presented considers a sensor (3), but more than one can be connected in order to use a room temperature value obtained by the combination of several measures from different places of the cooling container.

[30] The energy supply module (26) has an interface for the public electrical energy distribution and an interface for the vehicle battery. It also comprises a rechargeable battery capable of supplying the control device (5) in case of an interruption of the main supply. This can occur due to a cut off in the electrical supply or by a cut off of the vehicle's battery when its engine is turned off.

[31] The signalization module (21) allows getting a clear and simple visual perception of the system's state. It can be constituted, for example, by light-emitting diodes (LED). The presented implementation refers two LEDs, but is not limited to this number, one of green color to point out that there are temperature values being acquired and a red one to point out that the products' temperature exceeds the permissible limit.

[32] The display module (22) allows a more sophisticated person-machine interface, and is, for example, a digital display of 16 characters. It allows the configuration of parameters such as the sample interval between temperature readings, initial temperature of products, and the type of product to consider in the calculus, among others. During the acquisition process, it is possible to show the measured room temperature and the calculated temperature on the surface of products as well as other messages related to the operation of the control device (5).

[33] The button module (23) allows the user to interact with the system, both on the configuration operations and on requests for data transmission. The presented implementation refers four buttons, but it is not limited to this number: button 1 for basic configuration operations; button 2 to select the communication mode; button 3 to select the type of product; and button 4 to start data transmission.

[34] The processing module (28) is for example composed of a microcontroller that has the task of controlling all other modules included in the control device (5) as well as the task of executing the calculus program of the temperature on the products' surface depending on the room temperature obtained by the acquisition module (27).

[35] Figure 3 is a representative diagram of the system components and the way they are connected to each other.

[36] The control device (5) is connected to a battery (10) that maintains the system working during a significant period of time when there is no external supply. In case the system is placed inside a vehicle, the battery (10) is connected to the vehicle lighter plug (9). The battery may be connected to the public electricity distribution through the adapter (11). The room temperature sensor (3) placed in the cooling container is connected directly to the control system (5) through a cable. This connection can be done by wireless communication if the sensor (3) has wireless communication capabilities.

[37] The processing executed by the processing module (28) of the control device (5) is hereinafter described with reference to figure 4.

[38] In step Sl, of program start, the configuration state, the processing module (28) through the display module (22) presents the user several configuration options: a) the initial temperature of the product (2), meaning the temperature of the product (2) when it is placed inside the cooling container (1). This value can be changed by the user; b) sample interval among the samples of room temperature. The predefined value is of 10 seconds, allowing the user to increase or decrease this value through steps of 1 second; c) beginning of acquisition, wherein previous data in memory are ignored; d) acquisition continuation, wherein the temperature registration process is retaken maintaining the previous readings; e) inactive mode, which allows maintaining the collected data with minimum energy requirement, for example, by turning off the communication module (25), acquisition module (27), display (22), among others, unnecessary in this condition.

[39] In step S2 it is verified whether the user pressed any button of the button module

(23). Should that be the case, the processing proceeds in step S3 of buttons processing explained hereinafter with reference to figure 5, otherwise moving to step S4.

[40] In step S4 it is verified whether the sample interval for acquisition has ended. Should that be the case, the processing proceeds in step S5, where the acquisition and processing of the room temperature read by the sensor (3) takes place, being such explained hereinafter with reference to figure 6, otherwise moving to step S6.

[41] In step S6 it is verified whether the system is in configuration mode, that is, whether the configuration menu is being displayed to the user. Should that be the case, the processing proceeds to step Sl, otherwise moving to step S2 to verify the start in action of the button module (23).

[42] The flowchart of the processing carried out by the processing module (28) of the control device (5) is hereinafter described, with reference to figure 5, when a button of the button module (23) is pressed.

[43] In step S31 it is verified whether the configuration button was pressed. Should that be the case, the processing proceeds to step S 1 of figure 4, otherwise moving to step S32. [44] In step S32 it is verified whether the communication mode button was pressed.

Should that be the case, the processing proceeds to step S33 where the following mode of communication specified on an internal list, of the processing module (28), with every available mode is displayed. The communication mode displayed becomes automatically active. The program continues in step S6 of figure 4.

[45] In step S34 it is verified whether the button of the type of product was pressed.

Should that be the case, the processing proceeds in step S35 where the following type of product specified on an internal list, of the processing module (28), with all available types is displayed. The type of product displayed becomes automatically active. The program continues in step S6 of figure 4.

[46] In step S36 it is verified whether the button of data transmission request was pressed.

Should that be the case, the processing proceeds in step S37 where the calculated values of the temperature on the surface of products (2) are transmitted to the wireless mobile computational system (6) or to the interface device with a computational information system (7). The program continues in step S6 of figure 4.

[47] The flowchart of the processing carried out by the processing module (28) of the control device (5) is hereinafter described, with reference to figure 6, when a new value for room temperature obtained through the sensor (3) is registered and processed.

[48] In step S51 the processing module (28) obtains the actual value of the room temperature that is pointed out by the sensor (3) through the acquisition module (27). This value is used in step S52 to calculate the temperature on the surface of the product (2).

[49] In step S52 the temperature on the surface of the product (2) is calculated using a first-order physical system model of concentrated parameters wherein, for a certain product (2), the time constant is obtained by multiplying its thermal resistance, measured in ⁰CAV, by its thermal capacity, measured in KJ/°C. The processing module (28) calculates the temperature on the surface through the convolution of the transfer function of the first-order system by the room temperature measured by the acquisition module (27).

[50] In the calculus of the temperature on the surface of the product it is considered that it behaves as a first-order physical system, which is linear, causal and non- variant in time. It is considered that the parameters of the thermo system can be represented by concentrated parameters wherein, to a certain product (2), the time constant is obtained by multiplying its thermal resistance (R) by the thermal capacity (C). It is also considered that the thermal interaction between objects is null and that the existence of several objects inside the same container reflects on the room temperature read by the sensor (3).

[51] The processing module (28) calculates the temperature on the product's surface, also designated system output and represented by y(t), through the convolution of the system transfer function, also designated as impulse response and being represented by h(t), by the room temperature measured by the acquisition module (27) (T_room(t)) subtracted from the initial temperature of the product (T_11n). The last one is also designated as input signal and is represented by x(t). The function h(t) is an exponential function decreasing in time with decay given by the time constant referred above.

[52] The function surface temperature (y(t)), in its discrete way (y(n)), is therefore obtained for moment n through the calculus represented in the following algorithm. y(n)=T_im FOR k=0 TO n y(n) = y(n) + x(k)*h(n-k)

[53] The implementation of the method to determine the surface temperature is hereinafter shown by means of an example.

[54] A cooling container with a volume of 12m³ and a refrigerated pork meat sample with a volume of 0.37OxIO³ m³ are considered. This sample is characterized by the parameters of thermal resistance (R) equal to 3.070175439 ⁰CAV and thermal capacity (C) equal to 1396 KJ/°C. The initial temperature of the sample is 3.1 ⁰C.

[55] The results obtained are presented on figure 7. The graphic shows the thermal behavior of the considered sample when submitted to a constant room temperature of 15.7 ⁰C. The curve T_measured represents the measures carried out by a contact sensor. The curve T_estimated represents the temperature calculated by the described method (y(t)). The curve T_room represents the function of the room temperature along time (T_room(t)).

[56] In step S53 the temperature values obtained in steps S51 and S52 are saved on the non- volatile memory module (24). In step S54, the same values are displayed on the display module (22).

[57] In step S55 it is verified whether the temperature obtained in step S52 exceeds the maximum acceptable value for the type of transported or stored product (2). Should that be the case, the processing module (28) signalizes it through the signalization module (21), for example, turning on a red light emitting diode. The processing moves to step S6 of figure 4.

[58] The method and device described in this invention, to monitor and register transport and storage temperature of temperature-sensitive products, allows the real control of the products' temperature, by recording their surface temperature. The described invention allows a more objective and serious evaluation of the products' preservation conditions. Its implementation can be carried out in several ways: a) installation of the device in a distribution vehicle; b) installation in a refrigerated container for storing products c) use of the method to optimize the energy consumption of the refrigerated container, allowing higher room temperature variations as long as the surface tern- perature of the monitored product does not exceed the maximum limit.

[59] The presentation of the device to monitor and register the transport and storage temperature of temperature-sensitive products and the described method thereof is carried out as a non-limitative example that can be subjected to modifications and variations performed by a person skilled in the art, the modifications being however within the scope of the invention, as defined by the following claims.

Claims

[1] Device to monitor and register the transport and storage temperature of temperature-sensitive products, for thermo containers capable to maintain a conditioned temperature, comprising:

- a room temperature sensor (3), preferably placed next to the access door (4), to obtain the temperature inside the container (1) to which the products (2) are subjected to;

- a control device (5) that receives the signal from the temperature sensor (3) indicating the room temperature inside the cooling container (1);

- a power supply (10); wherein the control device (5) comprises an acquisition module (27) that obtains the actual value of the room temperature of the container (1) pointed out by the sensor (3); and a processing module (28) that calculates the surface temperature of the product (2) by means of processing the information of the surface temperature function, based on room temperature, the container volume, the product's volume and type. [2] Device according to claim 1, characterized in that the control device (5), when required by the operator, communicates the reading of the room temperature and the temperature calculated on the surface of products to a wireless and mobile computational system (6), preferably a mobile phone, PDA, personal computer or printer. [3] Device according to claim 2, characterized in that it is capable to make wireless and serial communication to an interface device (7) to make data transfer to a computational information system or remote printing.

[4] Device according to the previous claims characterized in that it is integrated with a receiving device (8) for the products' recipient, which is capable to receive data concerning the products' temperatures during transportation, through wireless communication and is composed by computational equipment, preferably a mobile phone, PDA or personal computer. [5] Device according to claim 1 comprising a communication module (25) that allows the communication of the temperature values to the interface device (7) and to the wireless mobile computational device (6), wherein the serial communication is preferentially RS232c and USB, and the wireless communication is preferentially Bluetooth and Ethernet IEEE 802.1 lb/g. [6] Device according to claim 1 comprising a non- volatile memory module

(24) preferably composed by a hard disk, a Flash memory and which saves the values of the room temperature and the values of the temperature on the surface of products.

[7] Device according to claim 1 comprising an acquisition module (27) that measures the room temperature in sample intervals defined in the software that is executed in the processing module (28).

[8] Device according to claim 1, comprising a power supply module (26) to interface with electricity distribution and a vehicle battery also comprising a rechargeable battery, capable of supplying the control device (5) whenever there is an interruption of the main power supply.

[9] Device according to claim 1, comprising a signalization module (21) that allows a simple and clear visual perception of the system's state which is preferably composed by light-emitting diodes.

[10] Device according to claim 1, comprising a display module (22) that allows having a sophisticated person-machine interface equipped with a digital display that permits the configuration of parameters such as the sample interval between temperature readings, initial temperature of products, type of product to consider in the calculus, among others.

[11] Device according to claim 1, comprising a button module (23) that allows the user to interact with the system, both on the configuration operations and on the requests of data transmissions, wherein there is preferably, a button for basic configuration operations, a button to select the communication mode, a button to select the type of product, and a button to transmit data.

[12] Device according to claim 1, comprising a processing module (28) composed by a microcontroller that has the task of controlling all the other modules belonging to the device control (5), as well as the task of executing the program to do the calculus of the temperature on the products' surface.

[13] Method of using the device to monitor and register the transport and storage temperature of products comprising the following steps:

- system configuration;

- getting the information from the room temperature sensor (3);

- calculating the temperature on the products' surface through the convolution operation of the room temperature obtained by the sensor, with the product transfer function, obtained by a first-order system model of concentrated parameters in which the constant of time related to a product is obtained by multiplying its thermal resistance by its thermal capacity;

- saving the calculated room temperature and product surface temperature;

- selecting the communication mode; - selecting the type of product;

- starting data communication.