Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B19/00—Machines, plants or systems, using evaporation of a refrigerant but without recovery of the vapour
  • F25B19/005—Machines, plants or systems, using evaporation of a refrigerant but without recovery of the vapour the refrigerant being a liquefied gas
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D29/00—Arrangement or mounting of control or safety devices
  • F25D29/001—Arrangement or mounting of control or safety devices for cryogenic fluid systems
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D29/00—Arrangement or mounting of control or safety devices
  • F25D29/003—Arrangement or mounting of control or safety devices for movable devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D3/00—Devices using other cold materials; Devices using cold-storage bodies
  • F25D3/10—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air
  • F25D3/105—Movable containers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D2700/00—Means for sensing or measuring; Sensors therefor
  • F25D2700/02—Sensors detecting door opening
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D2700/00—Means for sensing or measuring; Sensors therefor
  • F25D2700/12—Sensors measuring the inside temperature

Definitions

• the present invention relates to the field of transport and distribution of thermosensitive products, such as pharmaceuticals and foodstuffs, in refrigerated trucks.
• the heat extracted from the air allows, first of all, a complete evaporation of the cryogenic fluid flowing in the exchanger, then an increase in its temperature to a temperature close to that of the chamber.
• the cryogenic fluid exiting the exchanger is then rejected outside after giving up a maximum of cooling energy.
• a control / regulation mode is adopted which makes it possible to maintain the temperature of the product storage chamber at the value of the setpoint ("hold" phase) .
• the existing control modes are mainly based on control algorithms for the opening / closing of the cryogenic fluid supply valves of the exchanger or heat exchangers, or on taking into account the temperature differences between the inlet and outlet temperature. output of the fluid in and the exchanger.
• cryogen for example of liquid nitrogen
• One of the objectives of the present invention is then to propose a new management of the cryogen supply of such an indirect injection process, in particular making it possible to optimize the quantity of cryogen (for example of liquid nitrogen) required for lowering the internal air temperature to the chambers at or below a required setpoint, and maintaining these conditions during the various required transport phases.
• cryogen for example of liquid nitrogen
• the present invention proposes the implementation, at the output of the circuit (downstream of the exchanger or exchangers) of one or proportional valves, and the piloting of this or some of these proportional valves in an optimized way, control which, one conceives it, has a direct impact on the consumption of cryogen and on the profile of temperature obtained.
• valves can be controlled using their opening rate, opening rate which can vary in a range from 0 to 100% (100% corresponding to the maximum rate of opening of the valve).
• opening rate opening rate which can vary in a range from 0 to 100% (100% corresponding to the maximum rate of opening of the valve).
• the steering recommended here according to the invention proposes, to some moments and under certain conditions combined, to deliberately degrade the temperature conditions in the storage space and thus voluntarily agree to move away from the target temperature initially targeted. It can then be considered that with respect to the conditions of regulation traditionally practiced, as mentioned above, the invention provides the user / operator of the truck a mode of regulation that can be described as "ECO mode , Additional mode, and that the operator or the system can implement instead of the usual mode (in accordance with the prior art) when he deems it adequate or acceptable.
• the invention thus relates to a method for managing the cryogenic liquid supply of a truck for transporting thermosensitive products, of the type in which the truck is equipped with:
• a reserve of a cryogenic fluid such as liquid nitrogen
• an air circulation system for example of the fan type, capable of bringing the air inside the chamber into contact with the cold walls of the heat exchanger system
• thermosensors capable of determining the temperature of the atmosphere internal to said at least one chamber (Tj n t);
• a management and control unit able to regulate the internal temperature Tj nt to a set value T con s by ordering a closing or opening, or the degree of such opening / closing, a proportional valve located downstream of the exchanger system of a chamber considered;
• said management and control unit orders the maintenance of the opening of said valve located downstream of the exchanger system of the chamber in question at a rate of less than 80%.
• the invention introduces a voluntary limitation of the opening of the proportional valve in "standard mode", regardless of the deviation from the setpoint. This operating mode is therefore similar to a deliberately degraded mode of operation of the exchanger with the particular aim of minimizing the consumption of cryogen, while maintaining cold performance that can be described as sufficient.
• said unit is of course able to overcome this voluntary limitation / degradation and thus to restore the full power of the exchanger with an opening rate greater than 80% and in particular being in the vicinity of 100% as it is traditionally practiced, when the operator deems it necessary for various reasons including the environment of the truck.
• a mode of rapid descent in temperature of at least one of said chambers is adopted as follows:
• the setpoint value high AT CO ns-H being less than or equal to 20 ° C, and preferably less than or equal to 15 ° C.
• AT CO ns-H-con g in the case of frozen products, as soon as ⁇ is below a high set point freezing AT CO ns-H-con g one orders the closure or the decrease of the opening of said valve located downstream of the exchanger system of the chamber in question, AT CO ns-H-con g being greater than or equal to 10 ° C, preferably greater than or equal to 15 ° C, for example equal to 15 ° C ⁇ 5 ° C.
• ⁇ is lower than a high fresh charge reference value ATcons-H-charges, it is ordered to close or reduce the opening of said valve located downstream of the exchanger system of the chamber in question, ATcons-H-charge being greater than or equal to 2 ° C, preferably greater than or equal to 5 ° C, for example equal to 5 ° C ⁇ 3 ° C.
• a high freezing set point AT CO ns-H-con is adopted. g of 15 ° C ⁇ 5 ° C, and therefore typically from an internal temperature of -5 ° C (or even from an internal temperature of the room close to 0 ° C) it is agreed to reduce the flow supplying the exchanger, without wait to get closer to -20 ° C (as does the prior art) and thus accepting the induced temperature degradation and in particular the degradation of the kinetics of descent in temperature.
• the system thus applies, below the high setpoint AT CO ns-H (which is understood to be high compared to the limits causing a reaction according to the previously used modes of regulation) a reduced opening rate, compared to what it was before (Tauxo, in general the opening rate was after such an event according to the prior art to its maximum or close to its maximum , for example in the range of 80-100%) and thus the new (reduced) rate can be expressed as follows:
• the system will therefore apply, below the high setpoint AT CO ns-H a reduced opening rate (Rate 1), compared to what it was previously (Tauxo) s 'expressing as follows:
• Rate 1 ⁇ a Rateo the factor ⁇ 1 (or ⁇ ) depending on the elapsed time as mentioned above.
• ⁇ 1 (1- (TE * 1/3) / 100)
• the system will therefore apply, below the high setpoint AT CO ns-H a reduced opening rate (Rate 1), compared to what it was previously (Tauxo) s 'expressing as follows:
• Rate 1 ⁇ ⁇ a Rateo
• a door contactor which makes it possible to emit a signal and thus to increment an aperture number counter
• the system can also count the number of door openings by measuring the rise in indoor temperature in the box and the lowering temperature of the latter when it closes. And the identification of an extended stop can be effected by the difference in temperature between the inside temperature of the body and the outside temperature; if this difference is close to 5 ° C for example, we can consider that we are in the case of a prolonged stoppage and from this observation order the resetting of the counter.
• the following is an example of implementation carried out under the following conditions: -
• a door opening counter that can vary from 1 to 12 (beyond 12 door openings the variable will remain locked on 12).
• FIG. 1 is a partial schematic representation of a CTI installation according to current practice (prior art).
• Figure 2 is a schematic representation of the inner body to a transport truck according to the prior art, here comprising two product storage chambers, and in particular to better visualize the operation of the exchangers and the position of temperature sensors T1.
• FIG. 3 is a partial schematic representation of a CTI installation according to the present invention.
• Figure 5 shows the opening rate of the valve - in% of the maximum opening rate - as a function of the ⁇ (temperature difference between the indoor temperature and the set temperature), for two different values of the maximum rate.
• Figure 1 hereinafter appended is a partial schematic representation of an indirect injection installation according to current practice (prior art).
• the regulation of the quantity of cryogen, for example of liquid nitrogen, supplying such a CTI process (chamber internal to the truck, equipped with exchangers 3) is today made using at least two valves all or nothing (TOR) 1 and 6, an input and an output, the method then comprises at least the following elements, seen in the following order: a liquid nitrogen tank (not shown in Figure 1), a valve TOR 1 input, normally closed, which allows the supply of cryogen, for example nitrogen, the circuit;
• Ventilation systems (not shown in the figure for the sake of clarity but better visualized in the context of Figure 2 attached) positioned at the exchangers whose flow rates are regulated, to intensify the heat exchange between l ambient air of the chamber and exchangers (by sucking the air through the exchangers and forcing it to be in contact with the exchangers) and to homogenize the temperature of the air internal to the chamber.
• a temperature sensor (T1) controls the opening and closing of the digital input valve 1; it is located for example at the entrance of the air path in the exchangers and measures the air temperature of the chamber before cooling in the exchangers.
• a new supply circuit comprising, for example, a normally closed input digital valve, heat exchangers, a normally open digital output valve, etc. (an example of a two-chamber and position of the temperature probes is shown in Figure 2 attached).
• Refrigeration in the previous TOR mode typically takes place in two phases:
• the operation of the CTI process in this discrete mode is typically the following: when the measured temperature T1 is greater than the set temperature, the inlet valve 1 opens (the outlet valve 6 is already open by default) thus allowing the supply of exchangers in cryogen. The liquid nitrogen transforming into gas releases frigories which are absorbed by the air in contact with these exchangers. The fans recover this cooled air to circulate it in the room. Nitrogen gas is then released outside the chamber into the surrounding atmosphere. When the measured temperature T1 reaches the set temperature, the inlet valve 1 closes, thus stopping the supply of the exchangers in cryogen and thus the cooling of the air internal to the chamber. The reduction of the temperature of the chamber and its maintenance are obtained by opening and closing cycles of the valve 1.
• the frequency and duration of opening of the valve 1 will be higher during the fast descent phase than during the control / regulation phase.
• the rate of cryogen introduced into the heat exchangers will depend solely on the nitrogen pressure of the tank and the pressure drops of the various components of the installation. Consequently, this flow rate of cryogen is related to the design of the system and is, for a given installation, identical to each valve opening and this whatever the phase of the process.
• the flow rate of nitrogen not being adjustable, the amount of nitrogen is not optimized; which leads to overconsumption of nitrogen.
• FIG. 2 makes it possible to better visualize the detail of a present example of an internal box to a transport truck (in view of side), here comprising two product storage chambers (for example a room for fresh products and another chamber for frozen products), and in particular to better visualize the operation of the heat exchangers and the position of temperature sensors T1 for the mode exemplified here.
• each chamber upstream of a normally closed (“NC") inlet digital valve, each chamber is equipped with heat exchangers (vertical for chamber 1, horizontal at the top of chamber for chamber 2), where the cryogen circulates from the tank located under the truck, the gas streams obtained at the outlet of each chamber are sent to a collection pipe, here provided with a single normally open (“NO") exit valve.
• a temperature sensor T1 which manages the opening and closing of each digital input valve; she is placed :
• the probe thus measuring the temperature of the air in the chamber before cooling in the exchangers;
• FIG. 3 illustrates, in partial view, an embodiment according to the invention, with the following elements:
• a liquid nitrogen tank (not shown in FIG. 3), - a normally closed digital inlet valve 1 which allows the supply of cryogen, for example nitrogen, of the exchanger system 3 (constituted for this mode implementation of several vertical exchangers in parallel, but this is only one of the many configurations of exchangers commonly used in this industry);
• cryogen for example nitrogen
• a proportional analog valve 10 normally open, which allows the opening, closing and regulation of the feed of the exchangers 3;
• a digital valve 1 1 output (downstream of the proportional valve), normally open, output digital valve that is only optional according to the invention.
• the power management is based on the percentage of opening of the proportional valve 10, as a function of the air temperature of the chamber (Tj n t) and the desired target temperature. (Tset) -
• the proportional valve 10 is then commanded to to open (aperture percentage which is then generally close to 100%), the exchangers 3 are then supplied with nitrogen with a maximum flow rate and releases frigories which are absorbed by the air of the chamber (phase of
• data acquisition and processing means for example an automaton
• data acquisition and processing means to acquire all the necessary data (and in particular the pressure, temperature, internal to the chamber etc ..) and to feedback by giving orders to the system, in particular to close such or such valve, or to vary the rate of opening of the valve 10.
• FIG. 5 shows the opening rate of the valve - in% of the maximum opening rate - as a function of the ⁇ (difference in temperature between the inside temperature and the set temperature), for two different values of the maximum rate, Max rate 1 and Max rate 2, in the case of regulating a fresh product storage chamber.
• the abscissa represents the difference in temperature between the internal temperature of the chamber and the set temperature, a difference which is reduced to% knowing that 100% corresponds to a temperature delta of 15%. ° C.
• Tmax1 the regulation is not sufficiently adjusted to allow the flow rate to be reduced (the aperture rate applied is always at the maximum rate),

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Devices That Are Associated With Refrigeration Equipment (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2014
  • 2014-12-10 FR FR1462191A patent/FR3030025B1/fr active Active
• 2015
  • 2015-11-26 WO PCT/FR2015/053229 patent/WO2016092177A1/fr active Application Filing
  • 2015-11-26 EP EP15808749.4A patent/EP3230663A1/de not_active Withdrawn

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