WO2004065865A1

WO2004065865A1 - Compact solar ice maker unit

Info

Publication number: WO2004065865A1
Application number: PCT/DE2004/000055
Authority: WO
Inventors: Rainer Rudischer; Jörg WASCHULL
Original assignee: Institut für Luft- und Kältetechnik gGmbH; K-Metall Gmbh
Priority date: 2003-01-17
Filing date: 2004-01-16
Publication date: 2004-08-05
Also published as: DE10301878A1; DE10301878B4

Abstract

The invention relates to a compact portable system for producing water ice, which is electrically powered exclusively by means of a photovoltaic generator. The aim of the invention is to develop a solar ice maker system that is operated in a self-sufficient manner, can be used in a positionally flexible manner, and is operational within one hour after being connected to a water inlet. Said aim is achieved by a compact solar ice maker unit comprising a portable, closed or open housing structure (2) which encloses at least one power-regulated compression refrigeration machine for feeding ice makers (13) that can be connected individually or in groups, an energy-converting unit (3), an energy store (8), a feed water reservoir (16), and an insulated ice storage device (20). The inventive solar ice maker unit further comprises a photovoltaic generator that is pivotally mounted on the outside of the housing structure (2).

Description

Compact solar ice making unit

The invention relates to a portable compact system for the production of water ice, which is supplied exclusively by a photovoltaic generator with electrical energy. The preferred area of application for the self-sufficient, locally flexible system, which is operational within an hour of being connected to the water, is warm sunshine-rich regions that have only a poorly developed or no conventional energy infrastructure.

As the sole source of energy, solar energy - in addition to the diverse application for small consumers such as clocks, computers or lighting devices - has long been particularly popular where the energy demand is largely synchronized with the energy supply, e.g. B. in irrigation in arid and semi-arid zones. However, solar technology has also been successfully introduced for room and food cooling - especially through absorption refrigeration systems, the drives of which are heated by solar thermal energy.

Autonomous photovoltaic applications for refrigeration purposes are still only known from the literature and from comparatively few experimental or pilot plants (cf., for example, Rudischer, R .; Ulbrich, G .: Solar (photovoltaic)) 8th symposium "Photovoltaic solar energy", Staffelstein 1993; Gems, B .; Fett, F .: Photovoltaic room cooling as an alternative to the thermal process, and Meliß, M. et al.: PV cold store - autonomous system for food cooling. Ibid. 1994 and Rittmüller, I .; Rudischer, R .: PVCOOL - A simulation program for the design of PV-supplied cooling systems. Ibid., 1997).

In addition to developments for stationary operation, portable, photovoltaically powered devices for the direct cooling of food are also known. For example, DE 295 06 347 U1 describes a portable cool box with an active cooling element and photovoltaic cells integrated in the cover; DE 100 11 540 A1 discloses an exclusively photovoltaically supplied, transportable refrigerated container, the interior of which is designed as a cold storage room for food or medication. The coupling of a photovoltaic system with a compression refrigeration system for a cooling device, in particular a freezer or ice cream chest, DE 296 13 801 U1, however, claims that in addition to the solar-powered compressor, a mains-powered compressor.

[005] It has long been proposed (cf., for example, DE 39 20 058 A1, WO 08901119) to produce ice by means of absorption cooling systems operated by solar thermal means. Due to the comparatively complicated system structure, no applications of this principle for mobile ice production are known. Transportable ice making systems operated by photovoltaics are also ideal, although water ice in particular is predestined for the direct cooling of food (e.g. fish) in sunshine-rich regions because of its many advantages (low costs, high food and environmental compatibility, easy disinfection or disinfectability) , not known.

To date, only a stationary, predominantly photovoltaically supplied ice-making system with battery storage and compression refrigeration system, which has been in pilot operation in Mexico for about three years, has been presented in more detail (“First-Year Performance of the Chorreras PV-Hybrid Ice-Making System in Chihuahua, Mexico ", International Solar Energy Society, Proceedings of the Millenium Solar Forum 2000, Mexico City; Mexico, September 17-22, 2000, p. 513-518). The PV generator of the plant is separate from the other components firmly anchored on a concrete platform, the ice maker is located in a separate building.

Although there is a high and continuously growing need for ice for commercial and private applications in the outlined geographic regions and there is a sufficient available solar energy supply for the energy supply of corresponding ice-making systems, previous attempts have been made to introduce an inexpensive solar refrigerated goods storage because of the high Unit costs of the systems or due to technical shortcomings did not lead to the goal.

The object of the invention is to eliminate the disadvantages of the prior art. In particular, a photovoltaically driven, portable, stand-alone compact ice-making system for operation at high ambient temperatures is to be specified, which under realistic market conditions is competitive. is capable. The system is designed to ensure the daily supply of 250-300 kg of block or broken ice to commercial producers with cold storage or fresh keeping requirements (e.g. from large producers in the fishing, agriculture and pasture industry).

The object is solved by the features of claim 1. Appropriate embodiments of the invention result from the features of claims 2-15.

According to the invention, a solar compact ice-making unit is provided which consists of a transportable, closed or open housing structure and a photovoltaic generator which is pivotally attached to it on the outside. The housing structure, preferably a container with internationally standardized external dimensions, encloses at least one power-adjustable compression refrigeration machine for the supply of ice formers which can be switched on individually or in groups, an energy conversion unit including control, an energy store, a feed water storage container, a thermally insulated ice store and auxiliary units and - devices. The photovoltaic generator guarantees the exclusive energy supply. It is provided with a manually or electrically operated device, which enables the PV generator to be quickly operated, ie. H. its orientation according to the geographical location of the place of use for optimal electrical energy input, enables; the PV generator is folded up in the transport state.

According to the invention, the refrigeration machine has at least two, individually switchable refrigerant compressors which are speed-controllable and have different outputs. The evaporation of the refrigerant takes place in closed rooms within the ice-maker or in an intermediate heat exchanger that is connected to the compression refrigerator. The compressed refrigerant is liquefied either in air condensers, which are fixedly attached to the outside of the housing structure, or in liquid coolers, which are mounted inside the housing structure.

The ice-making unit has an electrical energy store which can absorb excess energy and can temporarily store it. correspond The necessary electrical energy converters such as charge controllers and inverters and a control unit are also part of the system according to the invention. A battery storage of small capacity or a capacitive electrical energy storage is preferably used as the energy storage.

The solar powered, containerized unit is ready for continuous ice production without modification after the water connection. The feed water storage container has facilities for treating the water to be frozen, which, like the facilities for water supply, are also operated exclusively photovoltaically; in particular, there is a device for disinfecting the water, preferably by means of UV radiation. At least two daily productions can be stored in the approximately 2 m ² ice store of the compact ice making unit.

Otherwise, auxiliary units and devices such as water and brine pumps, heat exchangers, expansion tanks, valves and an inclined plane, which enables the problem-free transport of the ice produced in the unit, are encompassed by the housing structure. Finally, the compact solar ice making unit has a connection option for an external power source, which can be used to maintain ice production in emergencies (failure of the photovoltaic generator).

With the invention, a portable, easy to set up and, above all, ready-to-use system for self-sufficient ice production is presented. The trouble-free transport by truck, ship or helicopter, the practically foundation-free installation, the solar energy supply via photovoltaic generator paired with a semi-automatic operation ensure that the compact ice making unit is ready for use within an hour without modification up to an ambient temperature of 48 ° C. The containerized ice making unit also offers the opportunity to sustainably reduce the high individual unit costs of solar developments.

[016] The invention is explained in more detail below using an exemplary embodiment. Fig. 1 shows the representation of the refrigeration cycle and the brine cycle of the solar ice making unit with several ice formers. The photovoltaic generator 1 is located outside the closed housing structure 2, with which it is pivotally connected, and supplies the generated electrical energy to the energy conversion unit 3 and 5 and a frequency-fixed alternating voltage for other consumers such as the water pump 6 and the brine pumps 7. An electrical energy store 8 is connected to the energy conversion unit 3, which buffers short-term fluctuations in energy supply and provides additional energy for the start-up of pumps and compressors. The refrigerant compressors 4 and 5 have different cooling capacities (e.g. in a ratio of 1: 2), so that by optionally switching on the compressors (4 or 5 or 4 and 5) and operating them at variable speeds, the energy consumption can be optimally adapted to the energy supply of the photovoltaic generator 1 can take place. Compressed refrigerant is liquefied in the air condensers 9, which are located outside the enclosure 2, with which they are firmly connected. The condensed refrigerant expands behind a controllable injection valve 10 and can extract thermal energy from a brine in an evaporator heat exchanger 11. Temperature-related fluctuations in the volume of the brine are compensated for by a compensating vessel 12.

The optional connection of water-filled ice formers 13, in which heat is extracted from the water to be frozen by the brine, the brine temperature can be kept in a range from, for example, -3 ° C to -7 ° C. To regulate the brine temperature, the brine pump in the ice mold cooling circuit is also speed-controllable. The mentioned brine temperature enables an acceptable ice production rate on the one hand and the highest possible evaporation temperature of the refrigerant, which in turn is responsible for the energy efficiency of the refrigeration. The compact ice maker has so many ice-makers 13 that at times of maximum energy provision by the photovoltaic generator 1, the entire cooling energy generated can be used by the ice-makers to produce ice without significantly lowering the brine temperature. [019] If the ice-making process in an ice former is completed, thawing of the ice body takes place through brine which has been heated in a heat exchanger 14 with the aid of the hot, condensed refrigerant. For this purpose, the corresponding ice mold is separated from the brine cooling circuit using the three-way valves 15 assigned to it and connected to the brine heating circuit. Then the ice body can easily, for. B. by tilting the ice mold, be removed from this. The cooling of the refrigerant in the heat exchanger 14 leads to an additional increase in the efficiency of the refrigeration cycle.

2 schematically shows the water supply to the ice-maker 13 and the devices for ice storage. The water reservoir 16 is filled with the aid of the water pump 6, preferably at times of high energy supply. The devices for treating the water to be frozen 17 are located in the water reservoir. After the ice body has been removed, the corresponding ice former is filled with fresh water via one of the valves 18 and is again available for an ice formation process. The finished ice slides over an inclined plane 19 into the thermally insulated ice store 20. If fresh ice is needed, it can be removed from this store from outside the enclosure 2 of the compact ice maker.

List of the reference symbols used

I photovoltaic generator 2 closed or open housing structure

3 energy converter unit

4 refrigerant compressors

5 refrigerant compressors

6 water pump 7 brine pumps

8 electrical energy storage

9 air condensers

10 adjustable injection valve

I I Evaporator heat exchanger 12 expansion tank

13 water-filled ice formers

14 heat exchangers

15 three-way valves

16 water storage / feed water storage container 17 facilities for treating the water to be frozen

18 valves

19 inclined plane

20 thermally insulated ice stores

Claims

claims

1. Solar compact ice-making unit, characterized in that it consists of a transportable, closed or open housing structure (2), the at least one power-adjustable compression refrigerator for supplying individually or group-connectable ice formers (13), an energy conversion unit (3) including control, one Encloses energy storage (8), a feed water storage container (16), a thermally insulated ice storage (20) as well as auxiliary units and devices, and from a photovoltaic generator (1) which is pivotally attached to the outside of the building structure (1) and which provides the exclusive energy supply guaranteed is formed.

2. Solar compact ice making unit according to claim 1, characterized in that the housing structure (2) has internationally standardized external dimensions.

3. Solar compact ice-making unit according to claim 1 and 2, characterized in that the refrigerator has at least two individually switchable refrigerant compressors (4, 5).

4. Solar compact ice making unit according to claim 3, characterized in that the refrigerant compressors (4, 5) are speed-controllable and have different performance.

5. Solar compact ice making unit according to claim 3 or 4, characterized in that the evaporation of the refrigerant takes place in closed spaces within the ice former (13).

6. Solar compact ice making unit according to claim 3 or 4, characterized in that the compression refrigerator and the ice-maker (13) are connected to one another via a coolant circuit.

7. Solar compact ice making unit according to claim 1, characterized in that the energy store (8) is a battery storage of low capacity or a capacitive electrical energy storage.

8. Solar compact ice making unit according to claim 1, characterized in that the feed water storage container (16) has one or more devices for treating the water to be frozen.

9. Solar compact ice making unit according to claim 8, characterized in that the feed water reservoir (16) has a device for disinfecting the

Has water by means of UV radiation.

10. Solar compact ice making unit according to claim 1, characterized in that the ice storage (20) has a capacity of at least two average daily outputs of the ice maker.

11. Solar compact ice making unit according to claims 1-10, characterized in that it has only photovoltaically operated devices for water supply and water treatment.

12. Solar compact ice making unit according to claims 1-6, characterized in that the compressed refrigerant is liquefied in air condensers (9) which are fixedly attached to the outside of the housing structure (2).

13. Solar compact ice making unit according to claims 1-6, characterized in that the compressed refrigerant is liquefied in liquid coolers, which are housed within the housing structure (2).

14. Solar compact ice making unit according to claim 1, characterized in that the auxiliary units and devices, the water and brine pumps (6, 7), the injection valve (10), the evaporator heat exchanger (11), the expansion tank (12), the heat exchanger (14), the three-way valves (15), the valves (18) and the inclined plane (19).

15. Solar compact ice making unit according to claim 1, characterized in that it has a connection option for an external power source.