Abstract:
An energy recuperation system for storing energy in a process for subsequent supply to an energy demand in the process comprises a recuperation storage system having a phase-change storage material. Recuperation circuitry between the energy loss/availability, the energy demand of the process/processes and the recuperation storage system to allow heat exchanges therebetween. A controller obtains temperature data with respect to the storage material, the energy loss/availability and/or the recuperation circuitry so as to selectively actuate the recuperation circuitry. An energy level calculator determines a storage capacity in the recuperation storage system as a function of temperature data of the storage material. An operation identifier determines when to store energy in the recuperation storage system and when to supply energy to the process as a function of the storage capacity and of process data, whereby the controller actuates the recuperation circuitry to store and supply energy from/to the process.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present patent application is a continuation of International Patent Application No. PCT/CA2008/000093, filed on Jan. 17, 2008, and claims priority on U.S. Provisional Patent Application No. 60/885,270, filed on Jan. 17, 2007. 
     
    
     FIELD OF THE APPLICATION 
       [0002]    The present application relates to energy management and, more particularly, to an energy recuperation storage system used in conjunction with a building or an industrial process or processes to recuperate energy. 
       BACKGROUND OF THE ART 
       [0003]    The ever-increasing costs of energy are associated with numerous factors: increasing energy demand for full capacity supply, diminishing stocks of fossil fuel, volatility of the supply capacity in view of political, geographical and meteorological factors. Therefore, energy management has rapidly evolved to minimize the impact of high energy costs, and cost variations. 
         [0004]    In a plurality of industrial processes, a product being produced may require to be heated and then cooled. As an example, in the food industry, some products are cooked by being exposed to heat, and are then cooled prior to being packed. In another instance, in the cosmetics industry, products such as creams, shampoos, must be heated and cooled as part of their production process. 
         [0005]    In these instances, the energy required to heat the product is often lost when the product is cooled. Accordingly, such energy consumption is inefficient, and has a direct effect on the cost of producing the product. Moreover, such non-optimized energy consumption could potentially prove harmful for the environment in the long run. 
       SUMMARY OF THE APPLICATION 
       [0006]    It is therefore an aim of the present application to provide an energy accumulator system that addresses the issues associated with the prior art. 
         [0007]    Therefore, in accordance with a first embodiment of the present application, there is provided an energy recuperation system for storing energy from an energy loss/availability in a process/processes for subsequent supply to an energy demand in the process/processes, comprising: a recuperation storage system having a storage material being selected so as to change phase during heat exchanges with the process/processes; at least one recuperation circuit between the energy loss/availability, the energy demand of the process/processes and the recuperation storage system for heat exchanges between (1) the energy loss/availability and the recuperation storage system, and (2) the recuperation storage system and the energy demand; a controller for obtaining temperature data with respect to at least one of the storage material, the energy loss/availability and the at least one recuperation circuit so as to selectively actuate the recuperation circuit; an energy level calculator for determining a storage capacity in the recuperation storage system as a function of temperature data of the storage material; and an operation identifier for determining when to store energy in the recuperation storage system and when to supply energy to the process/processes as a function of the storage capacity and of process data; whereby the controller actuates the at least one recuperation circuit to store energy from the process/processes in the recuperation storage system and to supply energy from the recuperation storage system to the process/processes. 
         [0008]    In accordance with the first embodiment, the energy recuperation system is used between a heating demand and a cooling demand of a process/processes, with the operation identifier determining when to store in the recuperation storage system cold energy from the heating demand and hot energy from the cooling demand, and when to supply hot energy to the heating demand and cold energy to the cooling demand of the process/processes as a function of the storage capacity and of the process data, whereby the controller actuates the at least one refrigeration circuit (1) to store in the recuperation storage system cold energy recuperated from the heating demand of the process/processes and to supply said cold energy from the recuperation storage system to the cooling demand of the process/processes, and (2) to store in the recuperation storage system hot energy recuperated from the cooling demand of the process/processes and to supply said hot energy from the recuperation storage system to the heating demand of the process/processes. 
         [0009]    Still in accordance with the first embodiment, the energy loss/availability is a cold energy loss. 
         [0010]    Still in accordance with the first embodiment, the energy recuperation system comprises two of said recuperation circuit, with one said recuperation circuit being provided between the energy loss/availability and the recuperation storage system for heat exchanges therebetween, and the other one of said recuperation circuit being provided between the recuperation storage system and the energy demand. 
         [0011]    Still in accordance with the first embodiment, the operation identifier is connected to a process controller controlling the process/processes, so as to obtain said process data from the process controller. 
         [0012]    Still in accordance with the first embodiment, the recuperation storage system has two separated storage materials, with a first one of the storage materials provided to store cold energy from the heating demand to then supply the cold energy to the cooling demand, and with a second one of the storage materials provided to store hot energy from the cooling demand to then supply the hot energy to the heating demand. 
         [0013]    Still in accordance with the first embodiment, the two separated storage materials are different storage materials. 
         [0014]    Still in accordance with the first embodiment, the energy loss/availability is cold energy available from any one of a cooling tower, dry cooler and heat rejection apparatus, with the at least one recuperation circuit being connected between the cooling tower and the recuperation storage system for heat exchanges between the cooling tower and the recuperation storage system, to store cold energy in the recuperation storage system. 
         [0015]    Still in accordance with the first embodiment, the energy recuperation system comprises a heat transfer apparatus and a cold transfer circuit, with the at least one recuperation circuit being provided between the energy availability and the heat transfer apparatus, and the cold transfer circuit being provided between the heat transfer apparatus and the recuperation storage system. 
         [0016]    Still in accordance with the first embodiment, the heat transfer apparatus is any one of a heat exchanger, a chiller and a heat pump. 
         [0017]    Still in accordance with the first embodiment, the energy recuperation system comprises a heat transfer apparatus provided between the energy availability and the recuperation storage system. 
         [0018]    Still in accordance with the first embodiment, the heat transfer apparatus is any one of a heat pump, a chiller, a heat pipe and a heat exchanger. 
         [0019]    Still in accordance with the first embodiment, the energy recuperation system comprises a heat recovery unit in heat exchange relation with the at least one recuperation circuit and with an alternative energy source, to store energy in the recuperation storage system from the alternative energy source. 
         [0020]    Still in accordance with the first embodiment, the storage material is a compound comprising at least one of alkanes, N-paraffin hydrocarbon chain, glycerin, water, tridecane, tetradecanes, pentadecane, hexadecane, heptadecane, hydrocarbon wax, glycerol, 1,2,3-Propanetriol, glyceritol, glycerol, estol, 1,2,3-trihydroxypropane, glycyl alcohol, triglycerides, fatty acids, esthers, iso-propyl palmitate, silicone gel, salt hydrates. 
         [0021]    In accordance with a second embodiment of the present application, there is provided a method for recuperating energy comprising: identifying energy loss/availability from an energy source; storing energy from the energy loss/availability by heat exchange between the energy loss/availability and a storage material such that the storage material changes phase through the heat exchange; identifying an energy demand in a process; and supplying energy to the energy demand by heat exchange between the storage material and the energy demand. 
         [0022]    In accordance with the second embodiment, identifying the energy loss/availability comprises identifying the energy loss/availability from a heating demand of a first process, and identifying the energy demand comprises identifying a cooling demand in the first process or in a second process, whereby storing energy comprises subsequently storing cold and hot energy in the storage material. 
         [0023]    Still in accordance with the second embodiment, the method comprises storing cold energy from the heating demand in a first one of the storage material, and storing hot energy from the cooling demand in a second one of the storage material such that the storage materials respectively change phase through the heat exchanges. 
         [0024]    Still in accordance with the second embodiment, the method comprises identifying energy loss/availability from an alternative energy source, and storing energy from the energy loss/availability by heat exchange between the alternative energy source and a storage material such that the storage material changes phase through the heat exchange. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a block diagram illustrating an energy recuperation system for batch recuperation in accordance with an embodiment of the present application; 
           [0026]      FIG. 2  is a block diagram illustrating an energy recuperation system for continuous recuperation in accordance with an embodiment of the present application; 
           [0027]      FIG. 3  is a block diagram illustrating the energy recuperation system of  FIG. 1 , as used with cold energy availability external to a process; and 
           [0028]      FIG. 4  is a block diagram illustrating the energy recuperation system of  FIG. 1 , with additional heat transfer apparatus and heat recovery unit. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Referring now to the drawings and more particularly to  FIG. 1 , an energy recuperation system is generally shown at  10 , and will hereinafter be referred to as the ERS  10 . In a first embodiment, the ERS  10  is used in conjunction with a process having a cooling demand/heat availability A and a heating demand/cool availability B. 
         [0030]    The cooling demand/heat availability A (hereinafter cooling demand A) is a part of the process in which the product must be cooled or, in the alternative, in which heat may be/must be absorbed. 
         [0031]    The heating demand/cool availability B (hereinafter heating demand B) is a part of the process in which the product must be heated or, in the alternative, in which heat can be released. 
         [0032]    The ERS  10  has a recuperation storage system  11 , a controller system  12 , a heat recuperation circuit  13 , and a cold recuperation circuit  14 . In the embodiment of  FIG. 1 , the recuperation storage system  11  is a reservoir having a storage material. The storage material is chosen as a function of the cooling demand A and of the heating demand B, so as to change phases (e.g., solid/liquid, or liquid/vapor) in the process of recuperating energy. 
         [0033]    The storage material is chosen so as to change phase (e.g., solid to liquid, liquid to gas or vice-versa) under generally atmospheric pressure within the recuperation storage system  11 , following a heat-exchange sequence with a thermo-fluid that is part of the heat recuperation circuit  13  and/or cold recuperation circuit  14 . It is preferred that the storage material undergo a phase change (e.g., liquid-solid and vice versa) as a function of the temperature variation required for the first refrigerant, so as to maximize the heat-retaining capacity of the energy recuperation by using the latent heat capacity of the recuperation refrigerant. 
         [0034]    The storage material is a compound of different materials which may include alkanes, N-paraffin hydrocarbon chain, glycerin, water, tridecane, tetradecanes, pentadecane, hexadecane, heptadecane, hydrocarbon wax, glycerol, 1,2,3-Propanetriol, glyceritol, glycerol, estol, 1,2,3-trihydroxypropane, glycyl alcohol, triglycerides, fatty acids, esthers, iso-propyl palmitate, silicone gel, salt hydrates, appropriately chosen as a function of the cooling demand A and the heating demand B. 
         [0035]    The recuperation storage system  11  communicates with the cooling demand A by way of the heat recuperation circuit  13  to absorb heat, and with the heating demand B by way of the cold recuperation circuit  14 , to supply heat as a function of the demand. 
         [0036]    In an embodiment, the heat and the cold recuperation circuits  13  and  14  are connected to a regeneration system which is used to charge the storage material at very low energy cost or with rejected energy, such as a dry cooler system with fans in heat exchange with the outside air (Direct free cooling module), the heat rejection of cooling tower of chilled water system or an economizer integrated to a chimney or on the exhaust air of a specific process. Examples are provided hereinafter. 
         [0037]    The heat recuperation circuit  13  and the cold recuperation circuit  14  typically are piping circuits extending between respective parts of the process and the recuperation storage system  11 . Both circuits  13  and  14  are in a heat-exchange relation with the process and with the energy accumulator  11 , but preferably not in fluid communication therewith. To be in heat-exchange relation, the circuits  13  and  14  are provided with heat exchangers, which are chosen as a function of the process and/or recuperation refrigerant. 
         [0038]    Thermo-fluids circulate in the circuits  13  and  14 , such as water, ethylene-glycol, propylene glycol, thermal oil, etc. Pumps or similar conveying means (compressed air network, etc.) are provided to induce the circulation of the thermo-fluids in the circuits  13  and  14 . It is contemplated to have the circuits  13  and  14  in fluid communication with one another in a global circuit with suitable valves and controls. Similarly, the circuits  13  and  14  may be a same single circuit if a single part of the process needs cooling and heating (e.g., a tank in which the product is heated and then cooled). 
         [0039]    The ERS  10  has a controller system  12 . The controller system  12  is a computer having a processor. The controller system  12  is connected to the cooling demand A, to the heating demand B, and to the recuperation storage system  11 , so as to obtain various information that will be used in operating the heat recuperation circuit  13  and the cold recuperation circuit  14  to recuperate energy. 
         [0040]    Referring to  FIG. 1 , the controller system  12  has a controller  20 . The controller  20  is connected to the recuperation storage system  11 , so as to obtain temperature data, or like parameters, associated with the storage medium. 
         [0041]    The controller  20  is also connected to the cooling demand A and to the heating demand B of the process, for instance by way of various sensors (e.g., pressure sensors, temperature sensors [dry bulb and wet bulb temperatures] and probes, and the like), so as to obtain information pertaining to the energy demand. More specifically, the process is often precisely controlled to ensure, for instance, that the product is produced according to given standards. Accordingly, the process is typically equipped with sensors and the like obtaining accurate parameter data (e.g., temperatures, pressures, etc.). It is therefore contemplated to connect the sensors of the process to the controller  20  such that the controller  20  obtains the parameter data illustrating the cooling demand A and the heating demand B. 
         [0042]    The controller  20  is connected to the various powered devices (e.g., pumps, solenoids valves, etc.) of the heat recuperation circuit  13  and of the cold recuperation circuit  14 , which induce the flow of thermo-fluid between the demands A and B and the recuperation storage system  11 . The controller  20  therefore commands actuation of the circuits  13  and  14 , as a function of the decisions taken by the controller system  12 , to recuperate and store energy in the recuperation storage system  11 . 
         [0043]    An energy level calculator  21  is associated with the controller  20 . The energy level calculator  21  receives the temperature data pertaining to the cooling demand A and to the heating demand B of the process, and to the storage medium in the recuperation storage system  11 . With the temperature data, the energy level calculator  21  calculates the real-time storage capacity in the recuperation storage system  11 . 
         [0044]    The storage capacity value is the amount of additional energy that can be stored in the recuperation storage system  11 , under a desired condition of the storage material. Considering that the storage material is preferably to change phase when accumulating heat, the storage capacity value may be a calculation of the proportion of storage material that has yet to change phase (i.e., the capacity to store latent heat). 
         [0045]    An operation identifier  22  is associated with the controller  20 . The operation identifier  22  receives the storage capacity value of the recuperation storage system  11  from the controller  20 , as calculated by the energy level calculator  21 . Other information that is provided to the operation identifier is the temperature data of the recuperation storage system  11 , and the heat demand value. 
         [0046]    The operation identifier  22  will therefore determine if and when one of heat recuperation circuit  13  and the cold recuperation circuit  14  is to be actuated to store energy in the recuperation storage system  11 , in order to optimize energy consumption in view of the demands/requirements of the process. 
         [0047]    Alternatively, a process controller C is provided to control the operation of the process. More specifically, a process is a sequence of steps that are often automated, whereby a process controller C typically controls the process, for instance by actuating the powered devices, by measuring the parameters associated with the process, etc. 
         [0048]    It is therefore considered to connect the process controller C to the operation identifier  22 , such that the process controller C may indicate, in the form of process info, that a given step of the process has been reached and that there is a cooling demand/availability A or a heating demand/availability B at this step of the process. 
         [0049]    With or without this additional process information, the operation identifier  22  determines whether and when to send actuation commands to the controller  20  such that either the heat recuperation circuit  13  or the cold recuperation circuit  14  is actuated to initiate energy recuperation. 
         [0050]    Moreover, a database  23  is provided to store process data. Such information may be considered by the operation identifier  22  to determine from the process parameters (e.g., temperature, pressure) when to initiate recuperation of energy through actuation commands. The process data stored in the database  23  may be updated. 
       First Example of Operation 
       [0051]    The operation identifier  22  determines that, as a function of the storage capacity of the recuperation storage system  11  and of an indication from the process controller C that the process has a cooling demand A, the ERS  10  is capable of absorbing energy. Actuation commands are sent to the controller  20  by the operation identifier  22 , such that the thermo-fluid is circulated between the recuperation storage system  11  and the cooling demand A. Heat is absorbed by the thermo-fluid and then released to the refrigerant in the recuperation storage system  11 . 
         [0052]    Throughout this heat exchange, the energy level calculator  21  calculates the storage capacity of the recuperation storage, which information is updated with the operation identifier  22 . Upon receiving process information from the process controller C indicating that the step requiring the cooling demand A is finished, or determining from the storage capacity that the heat exchange must end, the operation identifier  22  commands the controller  20  to stop the actuation of the heat recuperation circuit  13 . 
         [0053]    The operation identifier  22  will subsequently determine how the energy stored in the recuperation storage system  11  can be used. For instance, if the energy level in the storage system  11  is high, the operation identifier  22  may wait for a demand indication of the process controller C to have the cold recuperation circuit  14  actuated to meet the heating demand B. 
         [0054]    Therefore, the use of ERS  10  allows energy to be stored for later use. The demands A and B do not have to be synchronized for the heat exchange to occur, as the storage removes the factor of time from the heat exchange. 
       Second Example of Operation 
       [0055]    In a second example, the cooling demand/heat availability A is a chimney releasing the by-products of combustion to the atmosphere. Accordingly, when combustion occurs, the by-products are a continuous source of heat that would otherwise be lost. 
         [0056]    Therefore, the operation identifier  22 , receiving information from the energy level calculator  21  as well as temperature data from the chimney or indications from the process controller C, commands actuation of the heat recuperation circuit  13  to store energy in the recuperation storage system  11 . 
         [0057]    Upon restoring the energy level in the storage system  11 , the ERS  10  is in standby until there is a heating demand B. At this point, the operation identifier  22  commands actuation of the cold recuperation circuit  14  to provide heat to the heating demand B of the process, until the end of the demand B or depletion of the stored energy in the recuperation storage system  11 . 
       Third Example of Operation 
       [0058]    In a third example, referring to  FIG. 3 , the cooling availability B is the outside air. Accordingly, when proper conditions apply (appropriate wet bulb temperature and/or dry bulb temperature), the cold recuperation circuit  14  benefits from a continuous source of quasi-free cold or mild temperature heat to be stored and that would otherwise be unusable. The cold recuperation circuit  14  is connected to a cooling tower, a dry cooler, a heat rejection apparatus or the like, all of which are the cold availability B. 
         [0059]    Therefore, the operation identifier  22 , receiving information from the energy level calculator  21  as well as temperature data from the outside conditions sensors or indications from the process controller C, commands actuation of the cold recuperation circuit  14  to store energy in the recuperation storage system  11 . 
         [0060]    Referring to  FIG. 3 , it is contemplated to additionally provide a heat transfer apparatus  30  and a cold transfer circuit  31  between the cold recuperation circuit  14  and the recuperation storage system  11 . This heat transfer apparatus is used to separate the two cold circuits ( 14  and  31 ) in order to allow the cold transfer circuit to distribute energy to a sensible cooling process which cannot be mixed with the cold recuperation circuit fluid (for separate temperature control, for contamination risks reduction or for other physical reasons). This isolation pattern allows for a larger range of applications and energy consumption reductions with the recuperation from external cool availability. The heat transfer apparatus  30  is for example a heat exchanger, a chiller, or a heat pump. 
         [0061]    Upon restoring the energy level in the storage system  11 , the ERS  10  is in standby until there is a cooling demand B. At this point, the operation identifier  22  commands actuation of the cold recuperation circuit  14  to provide cold to the cooling demand B of the process, until the end of the demand B or depletion of the stored energy in the recuperation storage system  11 . 
       Fourth Example of Operation 
       [0062]    In a fourth example, referring to  FIG. 4 , a heat pump or heat transfer apparatus  40  is provided between the heating availability A and the heat recuperation circuit  13 . The heat transfer apparatus  40  is for instance a chiller (notably the heat rejection/condenser side), a heat pipe or a heat exchanger, and is provided to increase the coefficient of performance of the heat recuperating loop between the heat availability A and the recuperation storage system  11 . Using a supplementary heat pump or heat transfer apparatus  40  to provide the temperature differential, generated by the heat availability, through the heat recuperation circuit  13  to the recuperation system allows for an increase in the energy quality supplied (e.g. higher temperature or enthalpy content in the heat recuperation circuit  13 ) while reducing the entropy generation and then improving significantly the energy efficiency of the combined process. 
         [0063]    Therefore, the operation identifier  22 , receiving information from the energy level calculator  21  as well as temperature data from the heat availability A or indications from the process controller C, commands actuation of the heat recuperation circuit  13  to store energy in the recuperation storage system  11 . 
         [0064]    Still referring to  FIG. 4 , it is contemplated to additionally provide a heat recovery unit  41  in heat exchange relation with the recuperation storage system  11 . The heat recovery unit  41  may be connected to either one of the recuperation circuits  13  or  14  (although connected to the circuit  14  in  FIG. 3 ), and is typically used in case where cold or hot energy is periodically available (e.g., free cooling in Winter conditions). Accordingly, the heat recovery unit  41  represents another option to recuperate energy. 
       Alternative Embodiment 
       [0065]    Referring to  FIG. 2 , in accordance with another embodiment, the recuperation storage system  11  of the ERS  10  is divided into a first recuperation storage  11 A and a second recuperation storage  11 B. 
         [0066]    Accordingly, two opposite heat-exchange sequences can be performed simultaneously. For instance, in a first sequence of heat exchange, the heat recuperation circuit  13  circulates its thermo-fluid between the first recuperation storage  11 A and the cooling demand/heat availability A, so as to absorb heat from the cooing demand A. Simultaneously, the cold recuperation circuit  14  circulates its thermo-fluid between the second recuperation storage  11 B and the heating demand/cool availability B, so as to absorb heat from the heating demand B. 
         [0067]    Once suitable energy levels are reached in storage  11 A and storage  11 B, the sequence is reversed, in that the first recuperation storage  11 A supplies heat to the heating demand B, whereas the second recuperation storage  11 B absorbs heat from the cooling demand A. These sequences of heat exchange are controlled by the controller system  12  in the manner described above.