JP4577835B2 - Analysis method of heat flow in heat storage tanks - Google Patents

Description

  The present invention relates to a method for analyzing heat flow in a heat storage tank group. More specifically, the present invention relates to a method for analyzing heat flow of a heat storage tank group that performs heat flow analysis of the entire heat storage tank group by sequentially performing heat flow analysis of a single heat storage tank.

  As a numerical analysis method for a heat storage tank group (also referred to as a heat storage system) in which a plurality of conventional heat storage tanks are connected by a communication pipe, a technique for simultaneously analyzing the entire heat storage tank group as one is known (non- Patent Document 1). In this method, all the heat storage tanks constituting the heat storage tank group and the communication pipes between the heat storage tanks are generated and numerical analysis is performed by generating an analysis grid.

  In addition, in the conventional numerical analysis method for the heat storage tank group as in Non-Patent Document 1, when the communication pipe between the heat storage tanks is incorporated as a lattice constituting the analysis grid, the physical characteristics of the communication pipe are required. Therefore, an experiment using a model simulating a plurality of heat storage tanks was performed, and the analysis results of the communication pipe section obtained by numerical analysis for the entire heat storage tank group based on the evaluation formula obtained by the experiment or the experimental results were obtained. The communication pipe is incorporated as a lattice of the analysis grid.

Tsuji, Yukihiro Ito: “Application of numerical analysis methods in water heat storage tank design”, Abstracts of Annual Conference of Architectural Institute of Japan, pp.1051-1052, September 1998

  However, according to the numerical analysis method of Non-Patent Document 1, all the heat storage tanks constituting the heat storage tank group and the communication pipes between the heat storage tanks are generated to generate an analysis grid and perform numerical analysis. As the number of heat storage tanks increases, the number of lattices increases and the arrangement becomes complicated, and a lot of know-how is required to generate an analysis lattice. For this reason, it is hard to say that it is versatile.

  In addition, the analysis of the heat flow analysis for each heat storage tank constituting the heat storage tank group and the analysis of the action of each communication pipe portion made through the communication pipe to the adjacent heat storage tank are performed as a whole simultaneously. It is necessary to solve a matrix of degrees of freedom corresponding to the number of lattice elements of the lattice. Therefore, as the number of heat storage tanks constituting the heat storage tank group increases, the degree of freedom of the matrix to be solved increases, and accordingly, the calculation time when analyzing using the electronic computer, the performance and storage capacity of the electronic computer, etc. More computational resources are required.

  Furthermore, using the analysis result of the communication pipe part obtained by numerical analysis for the whole heat storage tank group based on the evaluation formula obtained by the experiment using the model simulating multiple heat storage tanks or the experiment result, In order to incorporate the communication pipe as a lattice element of the analysis grid, a model experiment is necessary, which contributes to an increase in cost.

  Furthermore, there are still many unclear points in the heat flow behavior in the heat storage tank group in which multiple heat storage tanks are connected, and it can be said that a model that can accurately express the phenomenon has been completed. Absent. In addition, the conventional modeling focuses on refinement by capturing the phenomenon in more detail and utilizing many experimental results, and as a result, the model is It is complicated and time-consuming to analyze.

  Therefore, the present invention has an object to provide a method for analyzing heat flow of a heat storage tank group that is versatile and can grasp the details of the heat flow behavior in the heat storage tank group in a short time even with a small amount of calculation resources. And

  In order to achieve this object, the inventors of the present application have made extensive studies on simplification of the analysis model and reduction of the calculation load. As a result, based on the results of previous experiments and analysis, It has the characteristics of a parabolic equation, and has come to know that the heat flow phenomenon can be reproduced by the space development and time progress in the downstream direction. The analysis method of heat flow of the heat storage tank group of the present invention is based on such knowledge, and the heat storage tank is intended for the heat storage tank group in which a plurality of heat storage tanks are sequentially connected by a communication pipe and fluid can pass through. The flow of fluid in the group is connected to the upstream heat storage tank, which is obtained as a result of the analysis of the heat flow analysis of the upstream heat storage tank, and the connection pipe is connected to the upstream heat storage tank. The heat storage analysis of the heat storage tank for the downstream heat storage tank is performed, and the result of the heat flow analysis for the downstream heat storage tank is used as the result of the heat flow analysis for the new heat storage tank. The heat storage tank group is obtained by sequentially performing the heat flow analysis of the heat storage tank alone for the further downstream heat storage tank connected to the tank through the communication pipe from the most upstream heat storage tank to the most downstream heat storage tank in order. To do the overall heat flow analysis To have.

  The heat flow analysis method of this heat storage tank group does not analyze all the heat storage tanks and communication pipes as a single unit at the same time, but utilizes the fact that physical quantities such as fluid temperature and flow rate propagate in almost one direction, Each heat storage tank constituting the heat storage tank group is analyzed as a single unit. Further, the communication pipe itself between the heat storage tanks is not a target of the analysis grid. Therefore, in order to perform analysis for each heat storage tank alone without generating an analysis grid that integrates all of the heat storage tanks and the communication pipes between the heat storage tanks, complex analysis grid generation for the entire heat storage tank group No need for know-how, so versatility is high. Here, in the heat storage tank group in which a plurality of heat storage tanks are connected by a communication pipe, the heat storage tank until the fluid flows into the communication pipe from the inlet of the heat storage tank group and flows out of the outlet of the heat storage tank group A heat storage tank on the upstream side of the fluid flow in the group is called an upstream heat storage tank, and a heat storage tank on the downstream side of the fluid flow is called a downstream heat storage tank.

  In addition, the heat flow analysis for the downstream heat storage tank is performed as a single heat storage tank using the results of the heat flow analysis for the adjacent upstream heat storage tank, and this analysis result is obtained for the new upstream heat storage tank. The analysis of the thermal storage tank is performed sequentially from the upstream thermal storage tank to the downstream thermal storage tank so that the thermal flow analysis of the downstream thermal storage tank is performed as a single thermal storage tank. To do. Thus, by performing the analysis of the heat storage tank alone for each heat storage tank, the degree of freedom of the matrix to be solved can be reduced as compared with the case where the entire heat storage tank group is analyzed simultaneously. As a result, the analysis of the heat flow behavior in the heat storage tank group can be processed in a short time even with a small amount of calculation resources such as the performance and storage capacity of the electronic computer. Furthermore, when the heat flow analysis is repeated for each heat storage tank by repeating the steps until the heat flow becomes steady, the analysis result for each heat storage tank is used using the analysis result for the adjacent upstream heat storage tank. It can be treated as independent. Therefore, the analysis for each heat storage tank can be processed in parallel, and the calculation time can be shortened.

  In addition, since the communication pipe itself between the heat storage tanks is not subject to the analysis grid, an evaluation formula or experimental result obtained by an experiment using a model simulating a plurality of heat storage tanks for the communication pipe part that was conventionally required The analysis result obtained by the numerical analysis for the whole heat storage tank group based on is not required. Therefore, it is possible to reduce the cost of performing the model experiment and save the labor of performing the analysis separately from the heat flow analysis of the heat storage tank group.

  As described above, according to the thermal flow analysis method of the heat storage tank group of the present invention, without generating an analysis grid that integrates all of the heat storage tanks constituting the heat storage tank group and the communication pipes between the heat storage tanks. Since the analysis for each heat storage tank is performed, know-how for generating a complex analysis grid for the entire heat storage tank group is not required, and the versatility is high. In addition, by performing the analysis of the heat storage tank alone for each heat storage tank, the degree of freedom of the matrix to be solved can be reduced compared to the case where the entire heat storage tank group is analyzed simultaneously, and the heat storage tank It is possible to analyze the heat flow behavior within the group in a short time even with a small amount of computing resources such as the performance and storage capacity of the computer. Furthermore, the analysis for each heat storage tank can be processed in parallel, and the calculation time can be shortened.

  Further, according to the heat flow analysis method of the heat storage tank group of the present invention, the communication pipe itself between the heat storage tanks is not the target of the analysis grid, and therefore, a plurality of heat storage tanks for the communication pipe portion that has been conventionally required The analysis result obtained by the numerical analysis for the entire heat storage tank group based on the evaluation formula obtained by the experiment using the model simulating the model or the experiment result is not required. Therefore, it is possible to reduce the cost of performing the model experiment and save the labor of performing the analysis separately from the heat flow analysis of the heat storage tank group.

  Hereinafter, the configuration of the present invention will be described in detail based on the best mode shown in the drawings. In this embodiment, as shown in FIG. 3, N heat storage tanks 12 from the first tank to the Nth tank (N ≧ 2) are connected by a communication pipe 14 as a heat storage tank group for performing heat flow analysis. The heat storage tank group 10 that accumulates the generated water will be described as an example. Further, the heat storage tank 12 on the upstream side of the fluid flow 16 from the inlet 13 of the heat storage tank group 10 to the outlet 15 of the communication pipe 14 is referred to as the upstream heat storage tank 12. The heat storage tank 12 on the downstream side is referred to as a downstream heat storage tank 12. Specifically, for example, in the relationship between the first tank and the second tank, the first tank is the upstream heat storage tank 12, and the second tank is the downstream heat storage tank 12. In addition, the thermal storage tank 12 which is in the most upstream side and has the inflow port 13 of the thermal storage tank group 10 is made into the 1st tank, and the number is provided to the thermal storage tank 12 in order toward this downstream from this 1st tank.

  In FIG. 1, the flowchart of one Embodiment of the analysis method of the heat flow of the thermal storage tank group 10 of this invention is shown. The heat flow analysis method of the heat storage tank group 10 of the present embodiment is based on the fluid temperature in the communication pipe 14 obtained as a result of the heat flow analysis on the upstream heat storage tank 12 with respect to the fluid flow 16 in the heat storage tank group 10 and The heat storage tank 12 alone is analyzed for the heat flow of the downstream heat storage tank 12 connected to the upstream heat storage tank 12 through the communication pipe 14 with the flow rate and pressure loss as analysis conditions, and the downstream heat storage tank 12 is analyzed. As a result of the heat flow analysis for the new upstream heat storage tank 12, the heat storage tank for the downstream heat storage tank 12 connected to the downstream heat storage tank 12 through the communication pipe 14. The heat flow analysis of the heat storage tank group 10 as a whole is performed by sequentially performing the heat flow analysis of 12 units in order from the first tank which is the most upstream heat storage tank 12 to the Nth tank which is the most downstream heat storage tank 12. Like to do

  Here, the analysis method of the heat flow of the heat storage tank group 10 of the present invention is connected to the temperature and flow rate of the fluid flowing out from the upstream heat storage tank 12 and the upstream heat storage tank 12 through the communication pipe 14. It is assumed that the temperature and flow rate of the fluid flowing into the downstream heat storage tank 12 are equal (see FIG. 2).

  The heat flow analysis method of the heat storage tank group 10 of the present embodiment sets the time t to 0 (zero) (S1), and first, the temperature and amount of water stored in each heat storage tank 12 as an initial state. Is set as an initial condition for each heat storage tank 12 (S2). As the water temperature for each heat storage tank 12, the water temperature measured for each heat storage tank 12 is used. Moreover, when there exists the thermal storage tank 12 in which the water temperature is not partially measured, for example, the measured temperature is used for the thermal storage tank 12 in which the water temperature is measured, and the water temperature in the thermal storage tank 12 in which the water temperature is not measured. Is set by performing linear interpolation or the like using the measured temperature of the heat storage tank 12 in which is measured.

  The amount of water for each heat storage tank 12 is calculated from the internal dimensions (specification values) and the water level for each heat storage tank 12. In addition, in the state before starting the operation | movement of the thermal storage tank group 10, the water level of all the thermal storage tanks 12 is uniform.

  Next, the water level for each heat storage tank 12 formed with the start of operation of the heat storage tank group 10 is calculated (S3). The water level for each heat storage tank 12 is the temperature and flow rate of water supplied from the inlet 13 set by the operation pattern of the heat storage tank group 10, and the temperature and amount of water for each heat storage tank 12 determined in S2. Furthermore, the calculation is performed based on the pressure loss in the communication pipe 14 between the upstream heat storage tank 12 and the pressure loss in the communication pipe 14 between the downstream heat storage tank 12. Since the method of calculating the water level based on the pressure loss in the communication pipe 14 is general, the details are omitted here. In addition, the pressure loss in the communication pipe 14 is based on the resistance coefficient arranged in the design handbook (for example, the Fluid Dynamics Handbook, etc.) and the inner diameter (specification value) of the communication pipe 14. It can be calculated using a pressure loss evaluation formula. Further, in the calculation of the water level of the most downstream N-th tank, the pressure loss at the outlet 15 is used instead of the pressure loss at the downstream communication pipe 14.

  The processing of S2 and S3 is performed only once for one operation pattern of one heat storage tank group 10, and is performed each time the operation pattern is changed in the middle. On the other hand, about the process (S4) which adds 1 to the time t, and makes the unit time pass, the required process is repeated as many times as necessary until the heat flow analysis of the entire heat storage tank group 10 is completed. Do. Here, while the operation pattern of the heat storage tank group 10 is not changed, water having a constant temperature and flow rate is continuously supplied from the inlet 13 of the heat storage tank group 10.

  The unit time is set based on the size of the heat storage tank 12 constituting the heat storage tank group 10 to be analyzed, the operation pattern of the heat storage tank group 10, and the like. For example, when the heat storage tank 12 is small and the operation pattern switching span of the heat storage tank group 10 is short, the time is short. When the heat storage tank 12 is large and the operation pattern switching span of the heat storage tank group 10 is long, the span is short. Long time. Specifically, for example, it can be set in the range of about 1 minute to 10 minutes, but is not particularly limited to this, and may be shorter or longer.

  Then, the process performed repeatedly until the heat flow analysis of the whole heat storage tank group 10 is complete | finished is demonstrated. First, 1 is added to time t, that is, the time is changed by the unit time, and the time is set as a new time t (S4).

  The temperature and flow rate of water flowing into the first tank from the inlet 13 of the heat storage tank group 10 are set (S5). This is set based on the operation pattern of the heat storage tank group 10.

  Next, it is determined whether or not the first tank is already in a steady state (S6). If it is not yet in a steady state (S6; NO), the heat flow analysis in the heat storage tank 12 for the first tank is performed. Perform (S7). On the other hand, if it is already in a steady state (S6; YES), the process proceeds to steps (S10 to S18) of heat flow analysis after the second tank.

  In the heat flow analysis (S7) in the heat storage tank 12 for the first tank, when the time t = 1 or the operation pattern is changed, the temperature of the water in the heat storage tank 12 obtained in S2 and S3 and With respect to the amount of water and the water level, the temperature and flow rate of the water flowing into the first tank set in S5, and the pressure loss in the communication pipe 14 between the second tank and the second tank are analyzed. Further, at time t ≧ 2 (that is, the time when one unit time or more unit time has elapsed since t = 1, and when the operation pattern is not changed), the time t = t−1 (that is, the current time). The temperature and flow rate of water flowing into the first tank at the time t = t set in S5 with respect to the temperature and amount of water in the heat storage tank 12 and the water level (time one unit time before the time) The pressure loss in the communication pipe 14 between the two tanks is performed as an analysis condition.

  Based on the result of the heat flow analysis in S7, it is determined whether or not the first tank is in a steady state (S8). If the first tank is in a steady state (S8; YES), the calculation of the first tank is completed. (S9), and the process proceeds to steps (S10 to S18) of heat flow analysis after the second tank. On the other hand, if not in a steady state (S8; NO), the process proceeds to the steps (S10 to S18) of the thermal flow analysis after the second tank as it is.

  Whether or not it is in a steady state is determined, for example, by whether or not there is a difference between the analysis result at time t = t and the analysis result at time t = t−1. For example, when the change amount of the temperature of the water flowing out from the communication pipe 14 of the first tank at the time t = t−1 and the temperature of the water flowing out at the time t = t is 0.1% or less, the steady state is reached. Judge that it is. However, the determination index for determining whether or not it is in a steady state and its determination level are not limited to this. For example, the determination level of the amount of change in the temperature of the water is made larger or smaller than 0.1%. You may do it.

  Then, the heat flow analysis after the 2nd tank is explained. For heat flow analysis of the nth tank (n ≧ 2), first, it is determined whether or not the nth tank is already in a steady state (S12). If it is not yet in a steady state (S12; NO), the nth tank The temperature and flow rate of the water flowing into the tank are set (S13). On the other hand, if already in a steady state (S12; YES), after setting n = n + 1 (S11), that is, after moving the target to the adjacent downstream heat storage tank 12, the procedure from S12 is repeated.

  The temperature and flow rate of water flowing into the nth tank from the communication pipe 14 at the time t = t as the analysis condition for performing the heat flow analysis of the nth tank at the time t = t is the upstream adjacent to the nth tank. The temperature and flow rate of the water flowing out from the communication pipe 14 obtained as a result of the thermal flow analysis at time t = t of the (n-1) th tank which is the side heat storage tank 12 are given (S13).

  The heat flow analysis in the heat storage tank 12 for the nth tank is (S14), the time t = t set in S13 with respect to the temperature, water amount and water level of the water in the heat storage tank 12 at time t = t−1. In addition, the temperature and flow rate of the water flowing into the nth tank from the communication pipe 14 and the pressure loss in the communication pipe 14 between the n + 1th tank are used as analysis conditions. In the thermal flow analysis of the Nth tank, which is the most downstream heat storage tank 12, the pressure loss at the outlet 15 is used instead of the pressure loss at the communication pipe 14 with the (n + 1) th tank.

  Based on the result of the heat flow analysis of S14, it is determined whether or not the nth tank is in a steady state (S15). If it is in a steady state (S15; YES), the calculation of the nth tank is finished. (S17), the process proceeds to step (S18) for determining whether or not there is an (n + 1) th tank.

  On the other hand, if the nth tank is not in a steady state (S15; NO), it is determined whether there is an (n + 1) th tank (S16). If there is an (n + 1) th tank (S16; YES), n = The procedure after S12 is repeated on (S11) which is set to n + 1. On the other hand, if there is no n + 1th tank (S16; NO), t = t + 1 is set (S4), and the procedure after S5 is repeated.

  After the calculation of the nth tank is completed (S17), it is determined whether there is an (n + 1) th tank (S18). If there is an (n + 1) th tank (S18; YES), n = n + 1 is set (S11). ) Repeat the procedure from S12 onward. On the other hand, when there is no (n + 1) th tank (S18; NO), the heat flow analysis of the entire heat storage tank group 10 is terminated (S19).

  As described above, by calculating the n + 1th tank at the time t using the calculation result of the nth tank at the time t, the calculation at the time t + 1 is performed during the calculation of the n + 1th tank at the time t. Since n tanks can be calculated in parallel (see FIG. 2), the calculation time can be shortened.

  In addition, although the above-mentioned form is an example of the suitable form of this invention, it is not limited to this, A various deformation | transformation implementation is possible in the range which does not deviate from the summary of this invention.

  For example, in this embodiment, the heat flow analysis of the heat storage tank 12 alone is repeatedly performed until all the heat storage tanks 12 constituting the heat storage tank group 10 are in a steady state, but the state of the heat storage tank group 10 after a certain time has elapsed. When it is desired to evaluate the thermal flow analysis, the time t is shifted by an amount corresponding to the passage of a predetermined time.

It is a flowchart which shows one Embodiment of the analysis method of the heat flow of the thermal storage tank group of this invention. It is a conceptual diagram of a division | segmentation sequential process. It is a schematic diagram of the heat storage tank group which the analysis method of the heat flow of the heat storage tank group of this embodiment makes object.

Explanation of symbols

10 heat storage tank group 12 heat storage tank 14 communication pipe 16 fluid flow

Claims (1)

  Obtained as a result of heat flow analysis on the upstream heat storage tank with respect to the flow of the fluid in the heat storage tank group, targeting a heat storage tank group in which a plurality of heat storage tanks are sequentially connected by a communication pipe and fluid can pass through. Heat flow analysis of a single heat storage tank with respect to the downstream heat storage tank connected with the upstream heat storage tank and the communication pipe given the fluid temperature and flow rate and pressure loss of the communication pipe section as an analysis condition, The result of the heat flow analysis for the downstream heat storage tank is the result of the heat flow analysis for the new upstream heat storage tank, and the further downstream heat storage tank connected to the downstream heat storage tank through a communication pipe Heat storage analysis of the entire heat storage tank group is performed by sequentially performing heat flow analysis of the heat storage tank alone from the most upstream heat storage tank to the most downstream heat storage tank in order. Analysis method of heat flow.

Images