A system for snow cold with a basin like snow store

Background of the invention

The invention relates to methods and systems which during the summer season is intended to use cold from snow in a store of snow to cool one or several buildings, or alternately for cooling purposes in processes.

Prior art

An established method for cooling larger buildings is to use refrigerating machines. Cold from a central refrigerating machine is for example used for cooling the supply air or for cooling with cooling baffles. An other example of a refrigerating machine is an air conditioning device adapted for cooling a single room. Refrigerating machines are used for cooling purposes in different kinds of processes.

As an alternative to conventional refrigerating machines, a system for snow cooling may be used for cooling of buildings. In a system for snow cold naturally frozen water, such as snow or ice is used. In many cities where the amount of snow is considerable, it is common that snow is transported to a snow deposit. By transporting the snow to a snow store set up for the purpose and protecting the snow in the deposit against natural melting, it may be stored to the summer season and cold from the snow may be used for various cooling purposes.

A system for snow cold typically comprises a snow store, a pump and a heat exchanger. The snow store further typically comprises a filter system and an oil remover.

JP2002310583 discloses a facility for snow cold where the snow store is above the ground. A problem with the facility in JP2002310583 is that the snow store has to be erected vertically, for example using a front loader. A further problem is that the snow store has to be insulated all around when the snow store is closed for the season.

Snow stores for snow cold are known that are basin like. An advantage of basin like snow stores is that snow may be dumped down to a snow store from trucks, or alternatively snow may be distributed down to the snow store using a front loader. A further advantage is that a basin like

snow store only has one direction that has to be insulated when the snow store is closed for the summer season, namely the upper side. The upper side may for example be insulated using shavings or bark.

Known basin like snow stores has an outlet to a first tubing system at the bottom of the snow store. The bottom of such a basin like snow store is typically tilted towards the outlet. The outlet is typically attached to at least one pipe through which melt water is transported with a pump through a heat exchanger. The pump regulates the flow of melt water through a first tubing system in a system for snow cold. At the outlet a filter is provided that separates larger particles such as bark that is used as insulation of the upper side of the snow store. Before the heat exchanger are provided an oil separator and a filter fro particle removal that is adapted to filter out particles above a certain size. This is to protect the heat exchanger from being clogged. A problem is that if the melt water that runs along the bottom of the basin like snow store contains sizeable amounts of larger particles, the filter will be clogged comparatively often. The problem may be countered using a backflush filter. In the heat exchanger an energy transfer takes places from the cold transfer medium, typically water, in another piping system to the melt water. The temperature of the water in the second piping system is lowered in the heat exchanger. The water in the second piping system is distributed to for example a building where there is a need for cooling to a comfortable temperature. The second piping system may for example be a district cooling system. Melt water that has passed through the heat exchanger is returned to the snow store, for example by releasing water at the edges of the snow store through a number of placed mouths. Alternatively, the recirculating melt water may be sprayed over the snow store. After a period of snow melting a surplus of melt water typically occurs that then is drained from the system for snow cold.

As the basin like snow store typically is tilted towards the outlet placed at the bottom, the met water transports relatively large particles to the first piping system. A problem with known basin like snow stores having an outlet at the bottom is that not only smaller particles in sediment and other objects must be filtered out in at least one filter stage after the outlet, but also larger particles has to be filtered out.

In an ideal snow store the melt water runs relatively slowly through porous snow and therefore a good retaining time and contact with the snow is achieved. A problem with known basin like

snow stores is that melt water creates channels to the outlet that leads to a shorter retaining time and a lessened contact with the snow as compared to an ideal case.

JP2002235975 discloses a tank for snow cold with an outlet at the bottom of the tank to a first piping system. The tank comprises a number of thresholds. The thresholds give an improved retaining time and an improved contact for the water with the snow store. A remaining problem is that an amount of larger particles are transported in through the outlet. Further, the flow of melt water through the snow store is not controllable, which means that channelling cannot be countered.

Objects and summary of the invention

An object of the invention is therefore to provide a system for snow cold which reduces the number of particles in melt water that needs to be filtered out in a filter placed after an outlet to a first piping system from a basin like snow store. A further object of the invention is that the proposed system gives a better contact between the melt water and the snow store. An advantage of improved contact between the melt water and the snow store is that melt water that passes through a heat exchanger has a lower temperature than the melt water from previously known basin like snow stores, which improves the efficiency of energy transfer at the heat exchanger.

This object is attained by a system according to claim 1. Such a system comprises at least one well. The well comprises at least one opening with filtering elements on the sides of the well. The well may comprise several such opening which then are placed at even heights on the upper portion of the well. The well may further advantageously comprise a flanged lid. A flanged lid has a rim that extends beyond the side or sides of the well. In previously known basin like snow stores the bottom of the snow store is typically tilted towards an outlet at the bottom of the snow store, where a sizeable amount of sediment and particles are drawn in though the outlet. The well or wells in the system according to the invention comprises openings above the bottom of the snow store which reduces the amount of sediment and particles considerably that are drawn towards the openings as compared to the outlets of previously known snow stores. The system according to the invention may comprise several filtering elements at openings in the wells. Thus an improved primary filtering effect is achieved. The flanged lid contribute to decreasing the amount of particles and sediment that follows melt water into tubes attached to the well or wells and further out of the basin like snow store, as the flanged lid forces melt water from the upper

part of the snow store entering the openings to at least partially flow horizontally. The gravity thus contributes to transporting sediment and larger particles towards the bottom of the basin like snow store.

As previously mentioned, forming of channels by melt water is a problem with previously known basin like snow stores. A disadvantage of forming of channels is that the retaining time for the circulating melt water is decreased and that the contact between the water with the snow store is lessened as compared with an ideal case where melt water trickles through the pores of the snow in the lower water filled part of the snow store. In the system the elevated well or wells may comprise a number of openings for melt water at the upper part of each well, which gives a more even flow of melt water through the snow store, which improves the contact with the snow. A comparatively extensive degree of melting takes place at the sides of the snow store, which makes the melt water flow comparatively extensive at the sides and further along the bottom of the snow store. An advantage of the system is hat the flow of melt water is forced upwards from the bottom into the openings in the wells. If the wells comprise a number of openings, a given volume of melt water passes through a larger volume of snow as compared to previously known basin like snow stores with openings at the bottom, which counteracts formation of channels and thus improves the contact with surrounding snow.

A pipe is attached to each well which constitutes part of the circuit for circulating melt water. To further counteract undesired effects of formation of channels, a valve is provided at each of these pipes. As a valve is turned down or closed, the flow of melt water is diminished or ceases in the channels that may have formed to the corresponding well. The channels disappear as surrounding snow melts away, and thereafter the valve is opened again. The flow of melt water towards the openings of the well then passes through a larger volume of snow. Thus the contact between the melt water and the snow is improved. While the valve is turned down or closed, the flow to the other wells will increase, provided that a constant volume of melt water is pumped through the piping system. Further, the water that previously was drawn towards a particular well has to find new routes.

A system for snow cold according to the invention may be intended for cooling a number of objects within a geographically limited area, via a district cooling system. Alternatively, the system may be intended for cooling a single facility, such as a hospital or an office building.

Further, the system for snow cold may be used for processing cold in industrial processes or to reduce electric power consumption in a refrigerated storage facility.

Description of the drawings

The invention is described in detail with reference to the appended drawings, where

Fig. 1 shows a schematic overview of a system 1 according to the invention. The system comprises at least two elevated wells 2. The main part of the flow of melt water takes place through the snow and along the bottom of the snow store 3. The system according to the invention counteracts formation of channels, partly through that the openings are elevated from the bottom, and also because there are more openings than in a traditional snow store with outlet at the bottom of the snow store. The figure shows that in a system according to the invention, melt water at the bottom 13 is forced upwards towards the inlets in the elevated wells 2, which gives an improved retaining time and a better contact between the melt water and the snow. An improved retaining time gives a lower temperature of the circulating melt water than in previously known systems.

Fig. 2 shows a basin like snow store 3. An elevated well 2 with openings in its upper part means that sediment 14 that falls to the bottom is not sucked into the openings. Fig. 2 further shows that the flanged lid 17 forces in flowing water to at least partially being moved horizontally, which causes sediment from the upper part of the snow 6 to tend to fall to the bottom. A certain amount of sediment 14 settles on the lid.

Fig. 3 is a side view of an elevated well 2. The well in fig. 3 has a height that is larger the diameter of the well.

Fig. 4 shows an example of a basin like snow store 13 which comprises three elevated wells 2a, 2b, 2c. The main flow routes for melt water 5' are indicated in fig. 4.

Fig. 5 shows the same example of a basin like snow as in fig. 4. To each well 2a, 2b, 2c a pipe 15a, 15b, 15c is attached. In fig. 5 the valve 22c is closed which means that the inflow of melt water to the well 2c has ceased. The channels that melt water has formed towards the well 2c melts away when the melt water that previously has been drawn to the well 2c instead finds its way to the other two wells 2a, 2b.

Description of preferred embodiments

The system in fig. 2 comprises at least two elevated wells 2. The main part of melt water typically runs through the snow and along the bottom of the snow store 3. The figure indicates that the main part of the melt water is under a level 21 in the snow store. Return pipes 19 for melt water may be connected to outlets on the sides of the basin like snow store 3. Return pipes 19 for recirculating melt water may alternatively be attached to mouths that like water distributors for lawns spreads the recirculating melt water over the snow 6. The system according to the invention counteracts formation of channels, partly by the openings being elevated from the bottom, and also by that there are more openings than in traditional snow stores with openings at the bottom of the snow store, which makes it possible to vary the routes of flow. The figure shows that in a system according to the invention, melt water at the bottom 13 is forced upwards towards the inlets in the elevated wells 2, which gives an improved retaining time and better contact between the melt water and the snow. The figure further shows that the system comprises components such as a gravel- and an oil remover 7, a filter 8, a pump 9 and a heat exchanger 10. It may be considered obvious that the system may comprise a multitude of these components. Fig. 1 shows that a second piping system directs refrigerated water from the heat exchanger 10 to an object to be cooled 1 1, that for example may be a number of buildings. The pump 9 controls the total amount of melt water through the piping system 23 and thus through the openings 16 in the wells. Surplus melt water may be released out of the system trough a drain 20. The height of the wells is typically at least 0.5 metres, this is so that sediment that has not fallen to the bottom will not be sucked into the openings 16.

Fig. 2 depicts a basin like snow store 3. An elevated well 2 with openings 16 in its upper portion results in that sediment 14 that has fallen to the bottom is not drawn into the openings 16. Fig. 2 further shows that the flanged lid 17 forces in flowing water to at least partially being moved horizontally, which causes sediment from the upper part of the snow 6 to tend to fall to the bottom 13, instead of being drawn in through the openings 16. In fig. 2an exiting pipe 15 is arranged under the bottom of the snow store.

Fig. 3 is a side view of an elevated well 2. The well 2 comprises a number of openings 16 with filtering elements on the sides 2' of the well 2. The openings 16 are placed on the upper portion of the well 2. The filtering elements may be net like. The well 2 may be arranged on the bottom

13 in a number of ways. The well in fig. 13 comprises a bottom plate 18 that is arranged in the bottom 13 of the basin like snow store 3. The bottom plate 18 may for example screwed to a cast foundation. An other alternative is that the well 2 is cast to the bottom 13, which may be particularly advantageous if the bottom of the snow store is paved. The well 2 comprises a flanged lid 17 that extends outside the sides 2' of the well 2. The main body of the well 2 may advantageously be cylindrical. The man body may then be manufactured from a severed pipe. At one end of the severed pipe notches for the openings 16 may be made by for example turning. The well 2 may for example be made from polyethylene, glass fibre or stainless steel. The lid 17 may for example be glued, heated or welded to the main body of the well 2. The pipe 15 from the well 2 may be attached above the bottom 13. In this case breaking forces against the pipe 15 may advantageously be countered by the pipe resting on a sand bed. The pipe 15 may alternately be arranged under the bottom 13, which facilitates cleaning of the bottom 13 after the summer season when the system is out of use.

Fig. 4 shows an example of a basin like snow store 13 comprises three elevated wells 2a, 2b, 2c. A pipe 15a, 15b, 15c is attached to each well 2a, 2b, 2c. The pipes are advantageously joined at a place before the oil remover. The main flow routes for melt water 5' are indicated in fig. 4. The system according to the invention counteracts formation of channels, which gives the previously mentioned effects of longer retaining time and improved contact with the snow. Fig. 4 shows that in comparison with previously known snow stores where the bottom slopes towards an outlet at the bottom, the melt water follows a larger number of routes, and longer routes to the openings 16. At least two wells 2 are necessary for achieving the advantageous effects. In spite of the advantageous effects, a limited number of channels will appear at the bottom of the snow store 3.

Fig. 5 shows the same example of a basin like snow store as in fig. 4. At each pipe 15a, 15b, 15c is a valve 22a, 22b, 22c provided. In fig. 5 the valve 22c has been closed, which means that the in flow of melt water to the well 2c has ceased. The channels that melt water has created towards 5' the well 2c vanishes when the snow around it melts away. Melt water 5" from the area around the well 2c instead seeks its way towards the two other wells 2a, 2b.

Although the invention has been described in conjunction with a number of preferred embodiments, it is to be understood that various modifications may still be made without departing from the scope of the invention as defined by the appended claims.