SOLAR COLD ROOM WITH THERMAL INERTIA

Abstract

The thermal inertia cold room (*) is a room powered by solar energy. It is self-contained and maintains a positive temperature of +4°C in compartment (C1) and a negative temperature of -25°C in compartment (C2). The refrigeration circuit consists of a refrigeration compressor (17) and a natural convection thermal storage system (evaporator) known as eutectic plates (7), (8), and (23). The user sets the reference temperature for compartment (C1) by controlling the transfer fans (21) with a thermostat. The electrical energy produced by the photovoltaic solar panels (2) directly powers the compressor (17) via a hybrid inverter (14), which operates based on a control algorithm. This algorithm ensures a balance between the electrical power produced by the solar panels and the electrical power consumed by the refrigeration compressor (17).Figure for the summary: Figure 1 (*)The thermal inertia of a cold room is its ability to maintain the internal temperature.

Description

Title of the invention: SOLAR COLD ROOM WITH THERMAL INERTIA Technical field to which the invention relates

[0001] The project relates to refrigeration engineering and the food preservation sector, more specifically cold rooms.

[0002] The proposed cold room is hybrid powered by solar energy. In the event of a temperature drop in exceptional circumstances, it will be powered by a generator (16), powered by fuel, or an electrical network.

[0003] The cold room is composed of two compartments, a freezing compartment (C2) and a refrigeration compartment (Cl). It offers a reliable, efficient and compact solution for preserving fresh products in isolated regions, where energy costs are high. Cold production is done from photovoltaic solar panels (2) and energy management is controlled by an intelligent algorithm.

[0004] The thermal inertia cold room is a modular and innovative solution, it stands out from traditional cold rooms by the fact that it provides practical and professional solutions to the needs of food conservation and storage in several sectors: agriculture, hotels, restaurants, catering companies, etc.

[0005] (*)The thermal inertia of a cold room is its capacity to maintain the internal temperature State of the prior art

[0006] Solar batteries store the energy produced by photovoltaic panels to ensure power supply in all circumstances (day or night, clear or overcast sky). The batteries used with solar panels are slow discharge batteries (also called solar batteries).

[0007] Knowing that the cost of solar batteries is relatively high, given the increase in the prices of the materials that compose them, this cost often exceeds 40% of the solar cold room with batteries, which makes its amortization difficult.

[0008] The originality of the invention lies in the reduction of the cost of the cold room and at the same time the increase of its lifespan by the elimination of batteries and the integration in the refrigeration circuit of the room of the storage technology based on eutectic plate evaporators with natural convections (7), (8) and (23). This is a reliable and less expensive solution and the maintenance cost is almost zero, because it allows energy to be stored and released in the form of slow heat. This is an invention that could revolutionize cold chains. Purpose of the invention

[0009] To offer an economically less expensive and reliable solution based on renewable energies (photovoltaic solar) for the preservation of food in isolated sites and even the reduction of electrical energy consumption in sites connected to the network.

[0010] The cost of the cold room based on an evaporator with eutectic plates with integrated natural convection (7), (8) and (23) whose lifespan is unlimited is significantly lower than that using solar batteries. The cost of the eutectic plates is equal to approximately 10% of the price of electrochemical batteries, whose average lifespan is only four years. The eutectic plates with natural convection of the cold system are fully charged in 20 hours of sunshine (approx. 2 days) when the room is powered by solar energy only, 5 to 6 hours when it is powered from the network.

[0011] The total cost of the invention in its prototype stage is approximately 1.2 million DA with a useful volume of 6m3 for refrigeration (C2) and 3m3 for freezing (Cl), including a 5KVA generator, this cost will be considerably reduced in the case of mass production of the product.

[0012] The absence of solar batteries considerably reduces the cost of maintaining the cold room.

[0013] The technique used thanks to the algorithm of the control of the hybrid inverter (14) allows the progressive variation of speed of the compressor and the condenser fan, which prevents mechanical wear and overheating of the winding, which will increase the life span of the refrigeration unit (17), and the elimination of repeated breakdowns usual in conventional cold rooms.

[0014] The technique developed in the invention, with its advantages, can be adapted according to the needs for large capacity cold rooms.

[0015] The developed algorithm for controlling the hybrid inverter (14) allows adaptive operation at low sunshine rates. After the first start-up of the cold room and the setting of the desired reference temperature in the compartment (Cl), the room operates autonomously and automatically thanks to the auto star control.

[0016] The cold room can be designed in different volumes to facilitate movement and transport directly to any isolated site, such as life bases and construction sites.

[0017] The innovation falls within the context of eco-design, through the use of renewable energies. The non-use of conventional chemical batteries for storage makes it very ecological and has a good impact on the environment. Statement of figures

[0018] [Fig. 1]: Overall perspective view of the cold room

[0019] [Fig.2]: View of the three sides of the cold room

[0020] [Fig.3]: Exploded view of the cold room. Presentation of the substance of the invention

[0021] The thermal inertia cold room is an original solution dedicated to isolated areas, it allows the production of cold by photovoltaic solar energy (2) without resorting to the use of electrochemical batteries which are expensive in terms of price and maintenance cost and whose lifespan is very limited.

[0022] The eutectic plate evaporators with natural convection (7), (8) and (23) consist of a flat, sealed, food-grade stainless steel box, capped on a coil in which the refrigerant (R404A) circulates. The box is filled with a eutectic (a mixture of two or more solutions whose physicochemical characteristics are very stable). This eutectic solution is non-toxic and non-harmful to the environment.

[0023] The freezing point of the eutectic solution is -40°C, which makes it possible to store and restore energy according to the operating conditions of the cold room, during the day for storage, at night for restitution. An auxiliary electrical source intervenes automatically to power the refrigeration unit (17), in the event of insufficient energy restored by the eutectic plates (7), (8) and (23).

[0024] The cold room with thermal inertia is composed of two positive (Cl) and negative (C2) compartments, separated by a 150mm thick sandwich panel (4) guaranteeing perfect thermal insulation. The photovoltaic panels (2) are placed on the roof of the room.

[0025] The thermal inertia cold room provides real-time data (via a simple application on a Smartphone) on the cold room, which will reduce the breakdown time and dispatch any necessary intervention. This is the Link GSM system also monitors the temperature in the two compartments (Cl) and (C2) every minute to analyze the performance of the room. This temperature data gives the alert before a breakdown occurs or plans technician interventions in advance.

[0026] The temperatures of the compartments are between 0°C and 4°C for the positive compartment (Cl) and (-20°C and -40°C) for the negative compartment (C2) with relative humidity of 80 to 95%. The system operates in outdoor ambient temperatures ranging from -10°C to +50°C.

[0027] The energy management system is equipped with a rack-mountable inverter (13) which makes it possible to power the control circuit (15) as well as the transfer fans (21) of cold air from the negative compartment (C2) to the positive compartment (Cl) when the temperature drops in the positive compartment (Cl).

[0028] For the safety of the chamber, the latter is equipped with two decompression valves (9) in the event of a pressure drop in the two compartments.

[0029] The chamber easily adapts to different nodes of the cold chain, offering lucrative value, its simple, robust and intelligent controls allow maintaining the temperature, humidity, airflow and temperature at ambient level inside the two storage compartments (Cl) (C2).

[0030] The multiple experiments of the chamber have given excellent results. The backup system allows very stable cooling for both compartments (Cl) and (C2) for several hours (20 to 30 hours) without sun.

[0031] The cold room is equipped with a remote control system based on the SIM card (GSM Block) (15), it allows preventive maintenance of the cold room to be carried out. The data is transmitted and analyzed, thus allowing the monitoring of the operating status of the cold room and the anticipation of any shutdown or breakdown.

[0032] The MPPT hybrid inverter (14) receives an input voltage of 450V DC and gives a variable output voltage of 220V AC three-phase, it is equipped with an input for the generator set (16) or the electrical network of 380V AC, For the protection of the room, the entire electrical installation, including the photovoltaic panels and the photovoltaic surge protector are provided with an earthing in accordance with the NFC 15-100 standard.

[0033] The connection of the solar modules is carried out according to a series diagram to give an input voltage to the hybrid inverter (14) of 450V DC with a power of 4 Kwc, Method of carrying out the invention

[0034] 1)-In order to protect the consumer and ensure increased quality of our invention, the design of the cold room complies with the safety and hygiene standards in force for the refrigeration installation, in particular the whole: NF, NFE 35-400, NFC15-100.

[0035] 2)-The cold room is built on a steel base (1) with a coating of Insulated, non-slip floor with good resistance to attack. The exterior walls are made of 1.5mm thick ribbed steel, the posts and stringers are made of approximately 4mm thick steel. For waterproofing the edges, the cladding panels (external) and the refrigeration panels (internal) have a male edge and a female edge (Detail B) allowing assembly by interlocking and airtightness is ensured by seals.

[0036] 3)-The cold room is designed in such a way that the noise levels do not exceed not the following sound pressure levels: (Order of 05 / 05 / 1988 and attached documents relating to airborne noise).

[0037] 4)-the cold room rests on a mechanically welded support (Detail I) (IPE100) to protect the chamber from any flooding and rising water in the installation location. It is equipped with a suspension earpiece (10) to facilitate its transport.

[0038] 5)-The insulation of the cold room with thermal inertia is provided by industrial sandwich panels (22) in pre-lacquered sheet metal, polyurethane foam core (Density: 40 kg / m3) injected between the two metal facings, thickness: 150mm, Thermal conductivity: 0.022 W / m.°C, reaction to fire equivalent Ml.

[0039] 6)-The room has a technical room (18 / A3) to house the equipment (the generator set (16), the refrigeration unit (17) and the control cabinet (15)), this room is equipped with ventilation grilles (19) to facilitate air circulation in order to ensure a bearable ambient temperature. The room is accessible through the doors (11) and (12) for access in case of maintenance.

[0040] 7)-On the upper part of the separation panel (4) of the two compartments (Cl) and (Cl) is the kit of three fans (21) which allow the transfer of cold air from the negative compartment (C2) to the positive compartment (Cl) in order to maintain the temperature at 4°C in the positive compartment (Cl) thanks to the thermostat (24).

[0041] 8)-The cold room is equipped, in both compartments, with shelves modular(20) according to recognized food hygiene standards.

[0042] 9)-Access to the two compartments (Cl) and (C2) is provided by the two doors (25) and (30) isothermal equipped with a tight closing system with tightening cams, frame seals, scraper brushes at the bottom of the door and an unlocking system from the inside. The door (30) of negative compartment (C2) is equipped with a heating resistor powered by a voltage of 220 Volts to prevent it from blocking.

[0043] 10)-The cold room is equipped with two analog thermometers (27) and (26) placed outside the chamber to visualize the temperature of two compartments and a thermostat (29) installed in compartment (C2) forming part of the control for switching between the electrical network and the solar panels.

[0044] 12)-The ceiling of the cold room is made of sandwich panels (6) covered with sheet metal (5) pre-painted, The roof is covered with a steel plate on which the supporting structure (S4) and (3) modular solar panels (2) are located, fixed by bolts (28), The orientation of this structure is fixed according to the location of installation (optimal inclination of the installation site).

[0045] 13)-The cold room is equipped with lighting by 15W LED strips (31), waterproof controlled by a waterproof switch.

Claims

Claims

1. The thermal inertia cold room is composed of two separate compartments: a positive compartment (Cl) and a negative compartment (C2), characterized in that it uses eutectic plates (the evaporator) with natural convection (7), (8) and (23) as well as photovoltaic solar energy for its operation, thus eliminating the need for electrochemical batteries. The thermal inertia cold room is equipped with a refrigeration compressor (17) powered by a hybrid inverter (14) which ensures continuous operation, including during periods of low availability of sunlight. The thermal inertia cold room switches to the electrical network or a backup generator (16) in the event of an exceptional drop in temperature.

2. The solar cold room with thermal inertia, according to the preceding claim [1], is equipped with a communication system via a Smartphone application. This system provides in real time the temperature readings of the two compartments (Cl) and (C2) as well as other relevant parameters of the cold room.

3. The thermal inertia cold room, according to the preceding claims [1] to [2], is powered by solar energy and uses thermal storage technology for a cold backup lasting 20 to 30 hours without sun. The design of the natural convection eutectic plate evaporator (8), (7) and (23) which allows the internal temperature of the room to be maintained.

4. The thermal inertia cold room, according to the preceding claims [1] to [3], is transportable and can be moved from one place to another. It should be noted that before starting up, the cold room must first be powered by the electrical network or generator [1] for approximately 20 hours to allow the eutectic plates to cool, and then start operating. The thermal inertia cold room includes a control system that will detect critical conditions of the temperature drop and switch to the electrical network or generator (16).

5. The cold room with thermal inertia, according to the preceding claims [1] to [4] is equipped with a plate evaporator

6.

7. eutectic (8), (7) and (23) with natural convection is equipped with a hybrid energy management system which allows the optimization of consumption of electrical energy, fuel in the case of use of a generator, with a reduced maintenance cost. The cold room with thermal inertia, according to claim [1] is equipped with a hybrid inverter (14) which ensures the switching of the power supply between the emergency generator (16) and the photovoltaic panels (2). The thermal inertia cold room, according to the preceding claims [1] to [6] is characterized by a stability of the supply voltage ensured by the inverter [1], thus ensuring a prolonged service life of the equipment used. The thermal inertia cold room operates in external ambient temperatures ranging from -10°C to +50°C by the use of reinforced insulation based on 150 mm sandwich panels (22).

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