Calculation device and method for calculating waste heat recovery efficiency

Abstract

This provides a technique for simply calculating the efficiency of waste heat recovery. [Solution] The waste heat recovery efficiency calculation device 200 of the present disclosure is a device for calculating the waste heat recovery efficiency in a fuel cell system 100 comprising at least one fuel cell unit 20, wherein the fuel cell unit 20 includes a fuel cell stack 21, and comprises a rotation speed data acquisition unit 201 that acquires rotation speed data representing the rotation speed of a pump 33 installed in a water path for recovering waste heat from the fuel cell stack 21 in the form of hot water, a waste heat recovery amount calculation unit 202 that calculates the waste heat recovery amount based on the rotation speed data, and an efficiency calculation unit 203 that calculates the waste heat recovery efficiency using fuel consumption data representing the fuel consumption of the fuel cell unit 20 and the waste heat recovery amount.

Description

[Technical Field]

[0001] This disclosure relates to a device and method for calculating waste heat recovery efficiency. [Background technology]

[0002] The waste heat from a fuel cell system is recovered and utilized in the form of hot water. By recovering and utilizing waste heat, the overall efficiency of the fuel cell system can be improved. Overall efficiency refers to the ratio (%) of final energy consumption to the amount of primary energy supplied. In a fuel cell system, primary energy is the chemical energy (calorific value) of pure hydrogen gas or hydrocarbon gas. Energy consumption is the sum of electricity supply and heat supply.

[0003] Patent Document 1 discloses a method for calculating the overall efficiency of a power generation system based on power generation efficiency and waste heat recovery efficiency. Waste heat recovery efficiency is calculated by measuring the cumulative heat amount supplied to the hot water supply equipment. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2004-213970 [Overview of the project] [Problems that the invention aims to solve]

[0005] The purpose of this disclosure is to provide a technique for easily calculating waste heat recovery efficiency. [Means for solving the problem]

[0006] This disclosure is, A device for calculating the waste heat recovery efficiency in a fuel cell system comprising at least one fuel cell unit, wherein the fuel cell unit includes a fuel cell stack. A rotation speed data acquisition unit acquires rotation speed data representing the rotation speed of a pump installed in a water path for recovering waste heat from the fuel cell stack in the form of hot water. A heat recovery amount calculation unit that calculates the amount of heat recovered based on the rotation speed data, An efficiency calculation unit that calculates the waste heat recovery efficiency using fuel consumption data representing the fuel consumption of the fuel cell unit and the waste heat recovery amount, The present invention provides a device for calculating waste heat recovery efficiency, which includes the following features.

[0007] In another respect, this disclosure is: A method for calculating the waste heat recovery efficiency in a fuel cell system comprising at least one fuel cell unit, wherein the fuel cell unit includes a fuel cell stack. To acquire rotational speed data representing the rotational speed of a pump installed in a water path for recovering waste heat from the fuel cell stack in the form of hot water, The amount of waste heat recovered is calculated based on the aforementioned rotational speed data, The waste heat recovery efficiency is calculated using fuel consumption data representing the fuel consumption of the fuel cell unit and the amount of waste heat recovered. This provides a method for calculating exhaust heat recovery efficiency, including [specific details omitted]. [Effects of the Invention]

[0008] According to the technology disclosed herein, the waste heat recovery efficiency can be calculated in a simple manner. [Brief explanation of the drawing]

[0009] [Figure 1] Configuration diagram of the fuel cell system according to Embodiment 1 [Figure 2] Configuration diagram of the computing device according to Embodiment 1 [Figure 3] A graph showing the relationship between pump rotation speed (rpm) and water flow rate (liters / min) in the hot water generation circuit. [Figure 4] A graph showing an example of a fuel cell system operating pattern. [Figure 5] Configuration diagram of the fuel cell system according to Embodiment 2 [Figure 6] Functional configuration diagram of the power supply system in Embodiment 3 [Figure 7] Sequence diagram for explaining the normal mode of the power supply system in Embodiment 3 [Figure 8] Chart for explaining the normal mode of the power supply system in Embodiment 3

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of well-known matters or duplicate descriptions of substantially the same configurations may be omitted.

[0011] The accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims thereby.

[0012] (Embodiment 1) Hereinafter, Embodiment 1 will be described using FIGS. 1 to 3.

[0013] [1-1. Configuration] FIG. 1 is a configuration diagram of a fuel cell system 100 according to Embodiment 1. The fuel cell system 100 includes a fuel cell unit 20, a hot water storage unit 50, and a calculation device 200 for calculating the waste heat recovery efficiency. The fuel cell unit 20 includes a fuel cell stack 21 and a control device 60. The calculation device 200 acquires necessary data from the control device 60 of the fuel cell unit 20 and calculates the waste heat recovery efficiency in the fuel cell system 100.

[0014] The computing device 200 is a general-purpose computer and is connected to the control device 60 via a data transmission circuit 300. The data transmission circuit 300 can be a communication interface such as USB (Universal Serial Bus), RS232, or RS485. However, the computing device 200 may be located away from the installation site of the fuel cell unit 20. In this case, the data transmission circuit 300 can be the internet. It is not essential that the computing device 200 can transmit data and / or commands to the control device 60. The data necessary for calculating the waste heat recovery efficiency may be transmitted unidirectionally from the control device 60 to the computing device 200.

[0015] The fuel cell stack 21 is, for example, a polymer electrolyte fuel cell stack.

[0016] The fuel cell unit 20 further comprises a heat exchanger 23 and a cooling circuit 30. The cooling circuit 30 connects the fuel cell stack 21 and the heat exchanger 23. The cooling circuit 30 is configured to circulate cooling water between the fuel cell stack 21 and the heat exchanger 23. The cooling circuit 30 includes a supply path 30a and a return path 30b. The supply path 30a connects the cooling water outlet of the fuel cell stack 21 to the high-temperature side inlet of the heat exchanger 23. The return path 30b connects the high-temperature side outlet of the heat exchanger 23 to the cooling water inlet of the fuel cell stack 21.

[0017] The cooling circuit 30 is comprised of at least one pipe. This also applies to other circuits and pathways.

[0018] The heat exchanger 23 is a liquid-liquid heat exchanger such as a double-tube heat exchanger, a shell-and-tube heat exchanger, or a plate heat exchanger. In the heat exchanger 23, the temperature of the cooling water decreases.

[0019] The fuel cell unit 20 further includes a pump 34 and a temperature sensor 36.

[0020] Pump 34 is located in the cooling circuit 30. More specifically, pump 34 is located in the return path 30b of the cooling circuit 30. Pump 34 includes a pump body 34a and a motor 34b. The motor 34b is connected to the pump body 34b. The flow rate of cooling water in the cooling circuit 30 can be adjusted by controlling the motor 34b. The motor 34b is, for example, a pulse motor.

[0021] The temperature sensor 36 is located in the cooling circuit 30. More specifically, the temperature sensor 36 is located in the supply path 30a of the cooling circuit 30. The temperature sensor 36 can detect the temperature of the cooling water at the cooling water outlet of the fuel cell stack 21. The temperature of the fuel cell stack 21 can be estimated from the temperature of the cooling water. The temperature of the cooling water at the cooling water outlet of the fuel cell stack 21 may be considered as the temperature of the fuel cell stack 21.

[0022] The fuel cell unit 20 further includes a bypass path 31, a heat exchanger 24, and a flow path switching section 39.

[0023] The bypass path 31 is a path that bypasses the heat exchanger 23. The starting end of the bypass path 31 is connected to the supply path 30a of the cooling circuit 30. The ending end of the bypass path 31 is connected to the return path 30b of the cooling circuit 30. The heat exchanger 24 is located in the bypass path 31. The heat exchanger 24 may be a gas-liquid heat exchanger such as a fin-and-tube heat exchanger. The flow path switching unit 39 is located at the connection point between the starting end of the bypass path 31 and the supply path 30a of the cooling circuit 30. The flow path switching unit 39 is typically a three-way valve. By controlling the flow path switching unit 39, the cooling water can be selectively directed to either the heat exchanger 23 or the heat exchanger 24. For example, when the hot water storage unit 50 is filled to its upper limit, the flow path switching unit 39 is controlled so that the cooling water is directed to the bypass path 31 and the heat exchanger 24. This causes the temperature of the cooling water to decrease in the heat exchanger 24.

[0024] The hot water storage unit 50 comprises a hot water storage tank 51 and a hot water generation circuit 52. The hot water generation circuit 52 is a water path for recovering waste heat from the fuel cell stack 21 in the form of hot water. The hot water generation circuit 52 includes a supply path 52a and a return path 52b. The supply path 52a connects the bottom of the hot water storage tank 51 to the low-temperature side inlet of the heat exchanger 23. The return path 52b connects the low-temperature side outlet of the heat exchanger 23 to the top of the hot water storage tank 51. Part of the hot water generation circuit 52 is located inside the housing of the fuel cell unit 20. A city water path 53 is connected to the bottom of the hot water storage tank 51. A hot water supply path 54 is connected to the top of the hot water storage tank 51. Low-temperature water is guided from the bottom of the hot water storage tank 51 to the heat exchanger 23 through the supply path 52a. Hot water is generated in the heat exchanger 23. Hot water is guided to the top of the hot water storage tank 51 via the return path 52b. City water W1 is supplied to the bottom of the hot water storage tank 51 via the city water path 53. Hot water W2 is supplied from the hot water storage tank 51 to the use point via the hot water supply path 54. Examples of use points include faucets, factory production lines, and heating equipment.

[0025] The fuel cell unit 20 further includes a pump 33, a temperature sensor 37, and a temperature sensor 38. The pump 33, temperature sensor 37, and temperature sensor 38 are located inside the housing of the fuel cell unit 20. However, the pump 33, temperature sensor 37, and temperature sensor 38 may be included in the hot water storage unit 50.

[0026] The pump 33 is located in the hot water generation circuit 52. More specifically, the pump 33 is located inside the housing of the fuel cell unit 20 in the supply path 52a of the hot water generation circuit 52. The pump 33 includes a pump body 33a and a motor 33b. The motor 33b is connected to the pump body 33b. By controlling the motor 33b, the water flow rate (liters / min) in the hot water generation circuit 52 can be adjusted. In other words, it is possible to estimate the water flow rate from the rotational speed instruction to the motor 33b.

[0027] According to this embodiment, a flow meter for measuring the water flow rate is not provided in the hot water generation circuit 52. Therefore, problems such as water leakage from the joint between the flow meter and the piping are less likely to occur. Furthermore, cost reduction can be expected by omitting the flow meter.

[0028] The temperature sensor 37 is located in the hot water generation circuit 52. More specifically, the temperature sensor 37 is located in the supply path 52a of the hot water generation circuit 52. The temperature sensor 37 can detect the temperature of the water at the low-temperature side inlet of the heat exchanger 23.

[0029] The temperature sensor 38 is located in the hot water generation circuit 52. More specifically, the temperature sensor 38 is located in the return path 52b of the hot water generation circuit 52. The temperature sensor 38 can detect the temperature of the hot water at the low-temperature side outlet of the heat exchanger 23.

[0030] The power generated by the fuel cell stack 21 is supplied to an external load of the fuel cell unit 20 through the power supply circuit 26. A DC-AC inverter 28 is located in the power supply circuit 26. The DC power generated by the fuel cell stack 21 is converted to AC power by the DC-AC inverter 28.

[0031] A current sensor 62 is positioned between the fuel cell stack 21 and the DC-AC inverter 28. The current sensor 62 detects the current output from the fuel cell stack 21. The detected current value is transmitted to the control device 60 and the computing device 200.

[0032] A fuel supply path 111 is connected to the anode of the fuel cell stack 21. The fuel supply path 111 is a path connecting the fuel cell stack 21 to a fuel supply source 113. The fuel supply source 113 can be a hydrogen storage tank, a hydrogen gas infrastructure, etc. Hydrogen gas is supplied to the fuel cell stack 21 as fuel from the fuel supply source 113 through the fuel supply path 111. The hydrogen gas is, for example, pure hydrogen gas with a volume concentration of 99% or more. The fuel cell system 100 may be a pure hydrogen fuel cell system.

[0033] A flow meter 112 is installed in the fuel supply path 111. The flow meter 112 detects the hydrogen gas supply flow rate (liters / min) at a predetermined sampling period. The detected supply flow rate is transmitted to the calculation device 200. The predetermined sampling period is any period between 1 second and 60 seconds, and is typically 3 seconds. As will be described later, the flow meter 112 is not essential. This is because it is possible to calculate the hydrogen gas supply flow rate from the value of the current output from the fuel cell stack 21 using a predetermined conversion formula.

[0034] In this embodiment, the flow meter 112 is located outside the fuel cell unit 20. In this case, the flow meter 112 can be shared by multiple fuel cell units 20.

[0035] The control device 60 is responsible for controlling the operation of the fuel cell unit 20. The control device 60 is composed of a DSP (Digital Signal Processor) which includes, for example, input / output circuits, a processor, and memory. The control device 60 acquires the detected temperature from temperature sensors 36, 37, and 38. Pumps 33, 34, and the flow path switching unit 39 are controlled according to the detected temperature.

[0036] [1-2. Operation] Figure 2 is a diagram of the configuration of the calculation device 200 according to Embodiment 1. The calculation device 200 includes a rotational speed data acquisition unit 201, a waste heat recovery amount calculation unit 202, and an efficiency calculation unit 203. The rotational speed data acquisition unit 201, the waste heat recovery amount calculation unit 202, and the efficiency calculation unit 203 are each composed of software stored in the memory of the calculation device 200. The calculation device 200 calculates the waste heat recovery efficiency (%) using the following formula (1). The calculation result is output to a display, printer, etc. According to formula (1), the instantaneous value of the waste heat recovery efficiency can be obtained.

[0037] Exhaust heat recovery efficiency (%) = 100 × (amount of exhaust heat recovered) / (calorific value of hydrogen gas) ... (1)

[0038] Heat recovery amount: Wr × ΔT × Cw Calorific value of hydrogen gas: Hr × HHV Wr: Water flow rate in the hot water generation circuit 52 (unit: liters / min) ΔT: (Detection value from temperature sensor 38) - (Detection value from temperature sensor 37) (Unit: °C) Cw: Specific heat of water (kJ / liter·°C) Hr: Hydrogen gas flow rate (unit: m) 3 / min) HHV: Unit volume (1 m³) 3 The higher heating value of hydrogen gas per unit area (=12790kJ)

[0039] The rotational speed data acquisition unit 201 acquires rotational speed data representing the rotational speed (rpm) of the pump 33 installed in the hot water generation circuit 52. More specifically, the rotational speed of the pump 33 is the rotational speed of the motor 33b. The rotational speed data representing the rotational speed of the motor 33b may be time-series data held by the control device 60 that controls the motor 33b. Therefore, the rotational speed data stored in the memory or storage of the computing device 200 may also be time-series data. The rotational speed data is transmitted from the control device 60 to the computing device 200 at any given time.

[0040] Figure 3 is a graph showing the relationship between the rotational speed (rpm) of pump 33 and the water flow rate (liters / min) in the hot water generation circuit 52. There is a correlation between the rotational speed of pump 33 and the water flow rate. For example, there is linearity between the rotational speed of pump 33 and the water flow rate. By experimentally investigating the relationship between the rotational speed of pump 33 and the water flow rate in advance, the equation of the straight line (A) shown in Figure 3 can be obtained. The equation of the straight line (A) is incorporated into the waste heat recovery amount calculation unit 202 and used when calculating the water flow rate from the rotational speed of pump 33.

[0041] According to this embodiment, the water flow rate in the hot water generation circuit 52 is calculated from rotational speed data representing the rotational speed of the pump 33. In other words, a flow meter is not required in the hot water generation circuit 52. Therefore, problems such as water leakage from the joint between the flow meter and the piping are less likely to occur. Furthermore, cost reduction can be expected by omitting the flow meter.

[0042] In this embodiment, the motor 33b mounted on the pump 33 is a pulse motor. In this case, the rotational speed data acquired by the computing device 200 is the rotational speed instruction given to the pulse motor. With this configuration, it is not essential to detect the actual rotational speed of the motor 33b using a detector such as an encoder. However, it is also possible to measure the actual rotational speed of the motor 33b using a detector such as an encoder and transmit the measured value as rotational speed data to the computing device 200.

[0043] The waste heat recovery amount calculation unit 202 calculates the waste heat recovery amount based on the rotation speed data acquired by the rotation speed data acquisition unit 201. Specifically, in addition to the rotation speed data, the waste heat recovery amount calculation unit 202 acquires temperature data from the control device 60. The temperature data represents the detected temperatures of temperature sensors 37 and 38, respectively. By subtracting the detected temperature of temperature sensor 38 from the detected temperature of temperature sensor 37, the temperature difference ΔT between the temperature of the water before receiving waste heat and the hot water generated by the waste heat can be calculated. With this configuration, the waste heat recovery amount can be calculated accurately. Note that the temperature data may also represent the temperature difference ΔT.

[0044] The temperatures detected by temperature sensors 37 and 38 are stored as temperature data in the control device 60 at a predetermined sampling period. Therefore, the temperature data stored in the memory or storage of the computing device 200 may also be time-series data. The temperature data is transmitted from the control device 60 to the computing device 200 at any time. The predetermined sampling period is, for example, any period between 1 second and 60 seconds, and is typically 3 seconds.

[0045] It is desirable that the rotational speed represented by the rotational speed data corresponds one-to-one with the detected temperature represented by the temperature data. In other words, it is desirable that the rotational speed of the motor 33b at the time when the temperature of water or hot water is detected by the temperature sensors 37 and 38 is identified by the control device 60 and transmitted to the calculation device 200. This improves the accuracy of the calculation of the waste heat recovery efficiency.

[0046] The efficiency calculation unit 203 calculates the waste heat recovery efficiency from the waste heat recovery amount and the calorific value of hydrogen gas based on equation (1). The waste heat recovery amount is obtained from the waste heat recovery amount calculation unit 202. The calorific value of hydrogen gas can be calculated by multiplying the hydrogen gas flow rate Hr by the higher heating value HHV of hydrogen gas per unit volume. The hydrogen gas flow rate Hr is the value detected by the flow meter 112. As explained above, the value detected by the flow meter 112 is transmitted to the calculation device 200 at a predetermined sampling period as fuel consumption data representing the amount of hydrogen gas consumed.

[0047] The heat recovery efficiency can be determined from the above process.

[0048] As shown in Figure 2, rotational speed data, temperature data, and fuel consumption data are stored in the calculation device 200 in a time series. Therefore, the waste heat recovery efficiency within a predetermined period (e.g., 1 hour) can be calculated using this data. For example, the amount of waste heat recovered for each sampling period can be calculated, and the cumulative value of the waste heat recovered over the predetermined period can be calculated. From the time-series fuel consumption data, the amount of hydrogen gas consumed over the predetermined period, that is, the cumulative value of the calorific value of hydrogen gas over the predetermined period, can be calculated.

[0049] Figure 4 is a graph showing an example of the operating pattern of the fuel cell system 100. In Figure 4, the horizontal axis represents time, and the vertical axis represents generated power. Power generation begins at time t0. Partial load operation is performed from time t1 to time t2. Output increases from time t2 to time t3. From time t3 onward, operation is performed at rated output.

[0050] The rotational speed data, temperature data, and fuel consumption data used in calculating the waste heat recovery efficiency should preferably be data from a period during which the power generated by the fuel cell unit 20 (kW) is equal to or greater than a predetermined value. More preferably, the waste heat recovery efficiency should be calculated using data from a period during which the power generated is approximately equal to the rated output. With such a configuration, the waste heat recovery efficiency can be calculated accurately. The "predetermined value" is, for example, 80% of the rated output.

[0051] Furthermore, it is desirable that the rotational speed data, temperature data, and fuel consumption data used in calculating the waste heat recovery efficiency are data from a period in which the amount of waste heat recovered per unit time is equal to or greater than a predetermined value. The unit time is, for example, any time in the range of 5 minutes to 120 minutes. Typically, the unit time is 1 hour. The amount of waste heat recovered per unit time can be calculated from the rotational speed data, temperature data, and fuel consumption data accumulated in time series in the calculation device 200. If the amount of waste heat recovered per hour is equal to or greater than a predetermined value, the data set included in the relevant period can be suitably used in calculating the waste heat recovery efficiency. With such a configuration, the waste heat recovery efficiency can be calculated accurately. The "predetermined value" is, for example, 80% of the amount of waste heat recovered per unit time that is predicted when the fuel cell system 100 is operating at rated output.

[0052] When the temperature detected by the temperature sensor 37 reaches a threshold temperature, the control device 60 assumes that the hot water storage unit 50 has been filled to its upper limit and controls the flow path switching unit 39 so that the cooling water is directed to the bypass path 31 and the heat exchanger 24. This allows the cooling water in the cooling circuit 30 to be kept at an appropriate temperature, and the fuel cell stack 21 to be sufficiently cooled.

[0053] When hot water is used, city water is supplied to the hot water storage tank 51, causing the temperature detected by the temperature sensor 37 to fall below the threshold temperature. When the temperature detected by the temperature sensor 37 falls below the threshold temperature, the control device 60 controls the flow path switching unit 39 so that cooling water is directed to the heat exchanger 23. This allows the recovery of waste heat to be resumed. Alternatively, instead of the temperature detected by the temperature sensor 37, the flow path switching unit 39 may be controlled based on the detection result of at least one temperature sensor installed inside the hot water storage tank 51.

[0054] If the temperature of the fuel cell stack 21 is below the threshold temperature, the pump 34 is driven at a rotational speed lower than the rotational speed of the pump 34 when the output of the fuel cell unit 21 is equal to the rated output. With this configuration, the temperature of the fuel cell stack 21 can be raised rapidly. The temperature of the fuel cell stack 21 is the value detected by the temperature sensor 36. The threshold temperature is, for example, any temperature in the range of 30°C to 70°C. "The output of the fuel cell unit 21 is equal to the rated output" means, for example, that the output of the fuel cell unit 21 is 90% or more of the rated output.

[0055] The control device 60 of the fuel cell unit 20 can also function as a heat recovery efficiency calculator 200. In other words, the control device 60 may calculate the heat recovery efficiency. An external computer for calculating the heat recovery efficiency is not required. In this case, the heat recovery efficiency calculated by the control device 60 is extracted externally through the data transmission circuit 300.

[0056] The type of fuel cell stack 21 is not limited to polymer electrolyte fuel cells. The fuel cell stack 21 may be other fuel cell stacks such as solid oxide fuel cells, phosphoric acid fuel cells, or molten carbonate fuel cells. For example, if the fuel cell stack 21 is a solid oxide fuel cell stack, heat is recovered from the exhaust gas of the fuel used to heat the solid oxide fuel cell stack. The cooling circuit 30 is replaced by the exhaust gas path.

[0057] In the fuel cell system 100 shown in Figure 1, it is not essential that the fuel cell unit 20 and the hot water storage unit 50 are clearly separated. For example, the fuel cell stack 21, heat exchanger 23, hot water storage tank 51, and other components may be arranged in a single enclosure or a single space without partitions.

[0058] The lower heating value (=10780 kJ / m³) is used to express the calorific value of hydrogen gas. 3 ) may be adopted.

[0059] The fuel cell stack 21, heat exchanger 23, and hot water storage tank 51 may be housed in a single enclosure. In other words, the fuel cell unit 20 and the hot water storage unit 50 do not need to be clearly separated.

[0060] In equation (1), it is possible to calculate the hydrogen gas flow rate Hr using the value of the current output from the fuel cell stack 21 instead of the detected value from the flow meter 112. Fuel consumption data, including the current value data from the current sensor 62 that measures the current output from the fuel cell stack 21, is transmitted to the calculation device 200. There is a correlation between the magnitude of the current output from the fuel cell stack 21 and the amount of hydrogen gas consumed. Therefore, the hydrogen gas flow rate Hr can be calculated from the current value (A) using the following equation (2). Equation (2) is based on the reaction equation in equation (3) where hydrogen gas flows into the current (e - This is based on the fact that 1 A (ampere) of current means that 1 C (coulomb) of charge moves per second, 1 mole of electrons corresponds to a charge of 96,485 coulombs (Faraday constant), and the volume of 1 mole of hydrogen gas at standard conditions is considered to be 22.4 liters.

[0061] Hydrogen gas flow rate (NL / min) =Current value (A) × 60 (sec / min) × 22.4 (L) × 1 / 2 ÷ 96485 (C) × Number of cells ... (2)

[0062] H2→2H + +2e - ...(3)

[0063] Instead of the detected value from the flow meter 112, the hydrogen gas flow rate Hr can be calculated from the current value and used to calculate the waste heat recovery efficiency. In other words, the detected value from the flow meter 112 can be replaced with current value data representing the magnitude of the current output from the fuel cell stack 21. This makes it possible to omit the flow meter 112.

[0064] (Embodiment 2) [2-1. Structure] Figure 5 is a diagram showing the configuration of the fuel cell system 400 according to Embodiment 2. The fuel cell system 400 comprises a plurality of fuel cell units 20. The configuration of the fuel cell units 20 is as described in Embodiment 1.

[0065] Multiple fuel cell units 20 are connected in parallel to a fuel supply path 111. Hydrogen gas is supplied as fuel to each of the multiple fuel cell units 20 from a fuel supply source 113 through the fuel supply path 111. Only one flow meter 112 is installed in the fuel supply path 111. The flow meter 112 detects the flow rate of hydrogen gas in the fuel supply path 111. The value detected by the flow meter 112 is the total flow rate of hydrogen gas. Therefore, the amount of hydrogen gas consumed by each of the multiple fuel cell units 20 cannot be directly determined from the value detected by the flow meter 112.

[0066] In this embodiment, the efficiency calculation unit 203 (Figure 2) calculates the hydrogen gas consumption of each of the multiple fuel cell units 20 by proportionally distributing the total hydrogen gas consumption of the fuel cell system 400 according to the magnitude of the current output from the fuel cell stack 21 provided in each of the multiple fuel cell units 20. Fuel consumption data, including current value data representing the magnitude of the current output from the fuel cell units 20, is transmitted to the calculation device 200.

[0067] As explained with reference to Figure 1, the fuel cell unit 20 is equipped with a current sensor 62. The control device 60 acquires the detected value (amperes) of the current sensor 62 as current value data representing the magnitude of the current output from the fuel cell stack 21 at a predetermined sampling period. The predetermined sampling period is any period between 1 second and 60 seconds, and is typically 3 seconds. The current value data is transmitted to the computing device 200 at any time. The memory or storage of the computing device 200 stores the current value data of the fuel cell stack 21 of each of the multiple fuel cell units 20 in the form of time-series data.

[0068] The magnitude of the current output from the fuel cell stack 21 is proportional to the hydrogen gas consumption. Therefore, the hydrogen gas consumption of each of the multiple fuel cell units 20 can be calculated from the current value data of each fuel cell stack 21 of each of the multiple fuel cell units 20 and the total hydrogen gas consumption detected by the flow meter 112. With this configuration, it is not necessary to provide a dedicated flow meter 112 for each of the multiple fuel cell units 20.

[0069] After calculating the hydrogen gas consumption of each of the multiple fuel cell units 20, the heat recovery efficiency of each of the multiple fuel cell units 20 is calculated based on equation (1). The heat recovery efficiency of each of the multiple fuel cell units 20 is stored in the memory of the calculation device 200 as the operating performance of each fuel cell unit 20. The overall heat recovery efficiency of the fuel cell system 400 can be calculated by summing the heat recovery amounts of each of the multiple fuel cell units 20 and dividing by the total hydrogen gas consumption of the fuel cell system 400.

[0070] Alternatively, the overall heat recovery efficiency of the fuel cell system 400 may be calculated by weighting the heat recovery efficiency of each of the multiple fuel cell units 20 according to the amount of hydrogen gas consumed, and then calculating the average value of the heat recovery efficiencies of the multiple fuel cell units 20.

[0071] As explained earlier with reference to equation (2), the hydrogen gas flow rate Hr can be calculated from the current value. Therefore, the hydrogen gas flow rate Hr can be calculated for each of the multiple fuel cell units 20 using equation (2), and the waste heat recovery efficiency of each of the multiple fuel cell units 20 can be calculated.

[0072] (Embodiment 3) The fuel cell system 100 of Embodiment 1 and the fuel cell system 400 of Embodiment 2 described above can be applied to a power supply system that supplies electricity by coordinating a fuel cell, solar power generation, and storage battery. The power supply system in Embodiment 3 will be described below with reference to Figures 6 to 8.

[0073] [3-1. Structure] Figure 6 is a functional configuration diagram of the power supply system 1a. Below, we will describe the functions of the power supply system 1a when it is equipped with a solar power generation facility 70a, a fuel cell facility 10a, and a battery storage facility 80a.

[0074] The power supply system 1a is connected to the commercial power supply 2. The power supply system 1a supplies power to the power load 5. The power supply system 1a is connected to the EMS (Energy Management System) server 92 via the network 90.

[0075] The power supply system 1a is a distributed power supply system. The power supply system 1a includes a solar power generation facility 70a, a fuel cell facility 10a, a battery storage facility 80a, a control device 40a, an electrical circuit 95, a distribution board 4, a current sensor 3a, and a current sensor 3b.

[0076] The solar power generation equipment 70a includes solar power generation modules 71a, 71b, and 71c, DC-DC converters 72a1, 72b1, and 72c1, DC-AC inverters 72a2, 72b2, and 72c2. In this embodiment, solar power generation modules may be read as solar power generation devices.

[0077] The DC power generated by the solar power generation module 71a is converted to DC power of different voltages by the DC-DC converter 72a1. The converted DC power is then converted to AC power by the DC-AC inverter 72a2. The AC power is supplied to the circuit 95.

[0078] The DC power generated by the solar power generation module 71b is converted to DC power of different voltages by the DC-DC converter 72b1. The converted DC power is then converted to AC power by the DC-AC inverter 72b2. The AC power is supplied to the circuit 95.

[0079] The DC power generated by the solar power generation module 71c is converted to DC power of different voltages by the DC-DC converter 72c1. The converted DC power is then converted to AC power by the DC-AC inverter 72c2. The AC power is supplied to the circuit 95.

[0080] The fuel cell equipment 10a includes fuel cell unit 101 and fuel cell unit 102. Each of fuel cell unit 101 and fuel cell unit 102 is, for example, a polymer electrolyte fuel cell (PEFC) system, a solid oxide fuel cell (SOFC) system, etc. In Embodiment 3, fuel cell unit may be read as fuel cell device.

[0081] Each of the fuel cell unit 101 and fuel cell unit 102 may be the fuel cell unit 20 in Embodiment 1 or Embodiment 2.

[0082] The fuel cell unit 101 includes a fuel cell stack 11a and a power converter 12a. The power converter 12a includes a DC-DC converter 12a1 and a DC-AC inverter 12a2. The DC power generated by the fuel cell stack 11a is converted to DC power of different voltages by the DC-DC converter 12a1. The converted DC power is converted to AC power by the DC-AC inverter 12a2. The AC power is supplied to the circuit 95.

[0083] The fuel cell unit 102 includes a fuel cell stack 11b and a power converter 12b. The power converter 12b includes a DC-DC converter 12b1 and a DC-AC inverter 12b2. The DC power generated by the fuel cell stack 11b is converted to DC power of different voltages by the DC-DC converter 12b1. The converted DC power is converted to AC power by the DC-AC inverter 12b2. The AC power is supplied to the circuit 95.

[0084] The battery storage system 80a includes a battery module 81a, a battery module 81b, a bidirectional DC-DC converter 83a, a bidirectional DC-DC converter 83b, and a DC-AC inverter 84. Each of the battery modules 81a and 81b is, for example, a lithium-ion battery module, a nickel-metal hydride battery module, a lead-acid battery module, etc. In this embodiment, the battery module may be read as a battery storage device.

[0085] The power discharged from the battery module 81a is converted into DC power of different voltages by the bidirectional DC-DC converter 83a. The converted DC power is then converted into AC power by the DC-AC inverter 84. The AC power is supplied to the circuit 95.

[0086] The alternating current power supplied from circuit 95 to the DC-AC inverter 84 is converted to direct current power. This direct current power is then converted to direct current power of different voltages by a bidirectional DC-DC converter 83a. The converted direct current power is used to charge the battery module 81a.

[0087] The power discharged from the battery module 81b is converted into DC power of different voltages by the bidirectional DC-DC converter 83b. The converted DC power is then converted into AC power by the DC-AC inverter 84. The AC power is supplied to the circuit 95.

[0088] The alternating current power supplied from circuit 95 to the DC-AC inverter 84 is converted to direct current power. This direct current power is then converted to direct current power of different voltages by a bidirectional DC-DC converter 83b. The converted direct current power is used to charge the battery module 81b.

[0089] Power can flow from circuit 95 to commercial power supply 2. Power can flow from commercial power supply 2 to circuit 95. Current sensor 3a detects the current flowing between circuit 95 and commercial power supply 2. By monitoring the current detected value of current sensor 3a, control device 40a can make the power flowing from commercial power supply 2 to power supply system 1a or from power supply system 1a to commercial power supply 2 follow a target power (e.g., 0W).

[0090] Power can flow from circuit 95 to power load 5 via distribution board 4. Current sensor 3b detects the current flowing to power load 5.

[0091] The solar power generation equipment 70a includes a control unit 47a. Each of the fuel cell unit 101 and fuel cell unit 102 includes a control unit 41a. The battery storage equipment 80a includes a control unit 48a. Hereinafter, the control unit 41a of fuel cell unit 101 may be referred to as the first control unit 41a. The control unit 41a of fuel cell unit 102 may be referred to as the second control unit 41a.

[0092] The control unit 41a may be the control unit 60 of the fuel cell unit 20 in Embodiment 1 or Embodiment 2.

[0093] The control device 40a is connected to, for example, a network 90. ​​The network 90 is a network that includes, for example, telecommunications lines such as the Internet. The network 90 may include public lines or dedicated lines. For example, in addition to the control device 40a, the EMS server 92 and various servers 93 are connected to each other via the network 90 so that they can communicate with one another.

[0094] The EMS server 92 may be a cloud server or an on-premise server. The EMS server 92 transmits instructions regarding the operating mode of the power supply system 1a to the control device 40a. The control device 40a receives instructions regarding the operating mode from the EMS server 92 via the network 90. ​​In this case, the control device 40a determines the control content for the operation of the solar power generation equipment 70a, the fuel cell equipment 10a, the battery storage equipment 80a, and the power reception from the commercial power source 2, according to the instructed operating mode. Based on the control content, the control device 40a transmits the necessary control signals for the operation of the solar power generation equipment 70a, the fuel cell equipment 10a, and the battery storage equipment 80a to the control units 47a, 41a, and 48a, respectively.

[0095] The various servers 93 provide, for example, power outage information and / or disaster information to the EMS server 92 via the network 90. ​​The various servers 93 may be operated, for example, by a power company and / or a weather company.

[0096] The control device 40a may also serve as the computing device 200 in Embodiment 1 or Embodiment 2. Alternatively, the EMS server 92 may also serve as the computing device 200 in Embodiment 1 or Embodiment 2.

[0097] [3-2. Operation] The control device 40a communicates with current sensor 3a, current sensor 3b, control unit 47a, first control unit 41a, second control unit 41a, and control unit 48a. The control device 40a also communicates with the EMS server 92 via the network 90. ​​Through these communications, the control device 40a generates control signals to control the control unit 47a, first control unit 41a, second control unit 41a, and control unit 48a.

[0098] The control unit 48a receives a control signal from the control device 40a. Based on the control signal, the control unit 48a controls the bidirectional DC-DC converter 83a, the bidirectional DC-DC converter 83b, and the DC-AC inverter 84. Controlling the bidirectional DC-DC converter 83a controls whether the battery module 81a is charging, in standby mode, or discharging. Controlling the bidirectional DC-DC converter 83b controls whether the battery module 81b is charging, in standby mode, or discharging. Controlling the DC-AC inverter 84 performs power conversion between DC and AC. Through these controls, the power flowing between the battery equipment 80a and the circuit 95 is controlled.

[0099] Specifically, the charging and discharging power of the battery module 81a is controlled by controlling the bidirectional DC-DC converter 83a. The charging and discharging power of the battery module 81b is controlled by controlling the bidirectional DC-DC converter 83b.

[0100] In the example shown in Figure 6, the charging and discharging of the battery module 81a is controlled by controlling the terminal voltage V1 of the bidirectional DC-DC converter 83a in relation to the terminal voltage V2 of the DC-AC inverter 84. The charging and discharging of the battery module 81b is controlled by controlling the terminal voltage V1 of the bidirectional DC-DC converter 83b in relation to the terminal voltage V2 of the DC-AC inverter 84.

[0101] The control unit 47a receives a control signal from the control device 40a. Based on the control signal, the control unit 47a controls the DC-DC converters 72a1, 72b1, 72c1, DC-AC inverters 72a2, 72b2, and 72c2. By controlling the DC-DC converters 72a1, 72b1, and 72c1, the output voltages of the solar power generation modules 71a, 71b, and 71c are adjusted. By controlling the DC-AC inverters 72a2, 72b2, and 72c2, power conversion between DC and AC is performed. Through these controls, power is extracted from the solar power generation equipment 70a to the circuit 95.

[0102] The first control unit 41a receives a control signal from the control device 40a. Based on the control signal, the first control unit 41a controls the DC-DC converter 12a1 and the DC-AC inverter 12a2. By controlling the DC-DC converter 12a1, the output voltage of the fuel cell stack 11a is adjusted. By controlling the DC-AC inverter 12a2, power conversion between DC and AC is performed. Through these controls, power is extracted from the fuel cell unit 101 to the circuit 95.

[0103] The second control unit 41a receives a control signal from the control device 40a. Based on the control signal, the second control unit 41a controls the DC-DC converter 12b1 and the DC-AC inverter 12b2. By controlling the DC-DC converter 12b1, the output voltage of the fuel cell stack 11b is adjusted. By controlling the DC-AC inverter 12b2, power conversion between DC and AC is performed. Through these controls, power is extracted from the fuel cell unit 102 to the circuit 95.

[0104] The operating modes of the power supply system 1a include a normal mode. The operating modes of the power supply system 1a may also include modes other than the normal mode, such as a power outage preparation mode.

[0105] Figure 7 is a sequence diagram illustrating the normal mode of the power supply system 1a. As shown in Figure 7, when the control device 40a receives an operation instruction for normal mode from the EMS server 92 (step S1), it obtains the load current detection result from the current sensor 3b (step S2). In addition, the control device 40a obtains data indicating the current amount of stored energy in the battery storage equipment 80a (step S3), as well as the generated power P from the solar power generation equipment 70a. PVObtain data indicating the achievements (step S4). The control device 40a determines the control content in the normal mode based on the acquired data (step S5). The power storage amount may be represented as a physical quantity having dimensions such as ampere-hour or watt-hour, or may be represented as a quantity that quantitatively indicates the relative power storage state with respect to the fully charged state and the fully discharged state such as State of Charge (SoC).

[0106] FIG. 8 is a chart for explaining the normal mode of the power supply system 1a. As shown in FIG. 8, in the normal mode, the commercial power supply 2 is in an energized state. The control device 40a calculates the power consumption PL of the power load 5 connected to the power supply system 1a based on the detection result of the load current. When the power consumption PL is smaller than the power generation power P in the solar power generation facility 70a PV the control device 40a stops the operation of the fuel cell facility 10a. In addition, the control device 40a charges the storage battery facility 80a if possible, and waits for charging in the storage battery facility 80a when the current power storage amount has reached the maximum value. When the power consumption PL is larger than the power generation power P PV and the power consumption PL is larger than the power generation power P PV and less than the sum of the maximum power generation power P of the fuel cell facility 10a FCMAX the control device 40a discharges the storage battery facility 80a. This discharge is adjusted to absorb fluctuations in the power consumption PL with a short cycle. The control device 40a operates the fuel cell facility 10a to generate power so as to compensate for the shortage of the power generation power P with respect to the power consumption PL PV . When the power consumption PL is larger than the sum of the power generation power P PV and the maximum power generation power P of the fuel cell facility 10a FCMAX the control device 40a generates power at the maximum power generation power P of the fuel cell facility 10a FCMAX . In addition, the control device 40a, with respect to the power consumption PL, the power generation power P PV and the maximum power generation power P of the fuel cell facility 10a FCMAXThe battery storage system 80a is discharged to compensate for the deficit in the sum of these. In these cases, the power supply system 1a can supply the necessary power to the power load 5 without power supply from the commercial power source 2. Power consumption PL = generated power P PV and the maximum power generation P of the fuel cell equipment 10a FCMAX If the sum of the two values ​​is greater and the stored energy is zero, the control device 40a permits receiving power from the commercial power source 2, and power from the commercial power source 2 is supplied to the power load 5 according to the power shortage.

[0107] The power supply system 1a can reduce the amount of power supplied from the commercial power source 2 even when the commercial power source 2 is energized, which is advantageous, for example, from the viewpoint of reducing environmental impact.

[0108] As shown in Figure 7, in normal mode, the control device 40a transmits control signals to the control units 48a, 47a, and 41a according to the control content determined as described above (steps S6, S8, and S10). For example, when charging or discharging the battery storage equipment 80a, the control unit 48a controls the operation of the bidirectional DC-DC converters 83a and 83b according to the control signal received from the control device 40a (step S7). The control unit 47a also controls the energization of the DC-DC converters 72a1, 72b1, and 72c1 according to the control signal received from the control device 40a (step S9). The control unit 41a adjusts the operating state of the fuel cell units 101 and 102 according to the control signal received from the control device 40a (step S11). As a result, the output from the fuel cell units 101 and 102 is adjusted so that, for example, the desired power generation is obtained in the fuel cell equipment 10a.

[0109] The control device 40a, at predetermined intervals, checks the load current, the current amount of stored energy in the battery storage equipment 80a, and the power generated by the solar power generation equipment 70a P. PV The track record, and the power generation P in the fuel cell facility 10a. FCData showing the actual performance is acquired (steps S12, S13, S14, S15). Based on this data, the control device 40a determines the control content again according to the relationship shown in Figure 8 (step S16), and transmits control signals to the control units 48a, 47a, and 41a according to this control content. The control units 48a, 47a, and 41a control the operation of the battery storage equipment 80a, the solar power generation equipment 70a, and the fuel cell equipment 10a, respectively, according to the control signals received from the control device 40a. From here on, the acquisition of data and determination of control content in the control device 40a, and the control of the operation of the battery storage equipment 80a, the solar power generation equipment 70a, and the fuel cell equipment 10a according to this control content are repeated. In the control device 40a, the determination of the control content for the operation of the fuel cell equipment 10a is repeated, for example, at 30-minute intervals.

[0110] (Other embodiments) As described above, Embodiments 1 to 3 have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these and can be applied to embodiments that have been modified, replaced, added, omitted, etc. Furthermore, it is possible to create new embodiments by combining the components described in the above embodiments.

[0111] The embodiments described above are for illustrative purposes only and may be modified, replaced, added, or omitted within the scope of the claims or equivalents.

[0112] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0113] (Technology 1) A device for calculating the waste heat recovery efficiency in a fuel cell system comprising at least one fuel cell unit, wherein the fuel cell unit includes a fuel cell stack. A rotation speed data acquisition unit acquires rotation speed data representing the rotation speed of a pump installed in a water path for recovering waste heat from the fuel cell stack in the form of hot water. A heat recovery amount calculation unit that calculates the amount of heat recovered based on the rotation speed data, An efficiency calculation unit that calculates the waste heat recovery efficiency using fuel consumption data representing the fuel consumption of the fuel cell unit and the waste heat recovery amount, A device for calculating waste heat recovery efficiency, equipped with [specific features / features].

[0114] According to the technology disclosed herein, the waste heat recovery efficiency can be calculated in a simple manner.

[0115] (Technology 2) The heat recovery efficiency calculation device according to Technical 1, wherein the pump includes a pulse motor, and the rotational speed data includes an instruction amount for rotational speed given to the pulse motor. With such a configuration, it is not necessary to detect the actual rotational speed of the motor using a detector such as an encoder.

[0116] (Technology 3) The waste heat recovery efficiency calculation device according to Technology 1 or 2 includes current value data representing the magnitude of the current output from the fuel cell stack as the fuel consumption data. With such a configuration, even if there are multiple fuel cell units, it is not necessary to provide a dedicated flow meter for each of the multiple fuel cell units.

[0117] (Technology 4) The efficiency calculation unit calculates the fuel consumption from current value data representing the magnitude of the current output from the fuel cell stack, and is a waste heat recovery efficiency calculation device according to any one of the technologies 1 to 3. With this configuration, it is possible to omit a flow meter for measuring fuel consumption.

[0118] (Technology 5) The heat recovery efficiency calculation device according to any one of the technologies 1 to 4, wherein the rotational speed data and the fuel consumption data are, respectively, data from a period during which the power generated by the fuel cell unit is above a predetermined value. With such a configuration, the heat recovery efficiency can be calculated accurately.

[0119] (Technology 6) The heat recovery efficiency calculation device according to any one of the technical specifications 1 to 5, wherein the rotational speed data and the fuel consumption data are, respectively, data from a period in which the amount of heat recovered per unit time is equal to or greater than a predetermined value. With such a configuration, the heat recovery efficiency can be calculated accurately.

[0120] (Technology 7) The waste heat recovery amount calculation unit calculates the waste heat recovery amount using the temperature difference between the temperature of the water before receiving the waste heat and the hot water generated by the waste heat, as described in any one of the technical specifications 1 to 6. With this configuration, the waste heat recovery amount can be calculated accurately. With this configuration, the waste heat recovery amount can be calculated accurately.

[0121] (Technology 8) The calculation device according to any one of the technologies 1 to 7, wherein the at least one fuel cell unit includes a plurality of fuel cell units, and the efficiency calculation unit calculates the fuel consumption of each of the plurality of fuel cell units by proportionally distributing the total fuel consumption of the fuel cell system according to the magnitude of the current output from the fuel cell stack provided in each of the plurality of fuel cell units. With such a configuration, it is not necessary to provide a dedicated flow meter for each of the plurality of fuel cell units.

[0122] (Technology 9) A method for calculating the waste heat recovery efficiency in a fuel cell system comprising at least one fuel cell unit, wherein the fuel cell unit includes a fuel cell stack. To acquire rotational speed data representing the rotational speed of a pump installed in a water path for recovering waste heat from the fuel cell stack in the form of hot water, The amount of waste heat recovered is calculated based on the aforementioned rotational speed data, The waste heat recovery efficiency is calculated using fuel consumption data representing the fuel consumption of the fuel cell unit and the amount of waste heat recovered. A method for calculating exhaust heat recovery efficiency, including [specific details omitted]. [Industrial applicability]

[0123] The technology disclosed herein is useful for fuel cell systems. [Explanation of symbols]

[0124] 20 Fuel Cell Units 21 Fuel cell stack 23,24 Heat exchanger 26 Power supply circuit 28 DC-AC Inverters 30 Cooling circuit 30a, 52a Outbound route 30b, 52b Return route 31 Bypass Route 33,34 Pumps 33a, 34a Pump body 33b, 34b Motor 36, 37, 38 Temperature sensors 39 Flow path switching section 50 Hot water storage units 51 Hot water storage tank 52 Hot water generation circuit 53. City water supply routes 54 Hot water supply route 60 Control device 62 Current Sensor 100,400 fuel cell systems 111 Fuel supply routes 112 Flow meter 113 Fuel supply source 200 Computing equipment 201 Rotational Speed ​​Data Acquisition Unit 202 Heat Recovery Amount Calculation Unit 203 Efficiency Calculation Unit 300 Data Transmission Circuits

Claims

1. A device for calculating the waste heat recovery efficiency in a fuel cell system comprising at least one fuel cell unit, wherein the fuel cell unit includes a fuel cell stack. A rotation speed data acquisition unit acquires rotation speed data representing the rotation speed of a pump installed in a water path for recovering waste heat from the fuel cell stack in the form of hot water. A heat recovery amount calculation unit that calculates the amount of heat recovered based on the rotation speed data, An efficiency calculation unit that calculates the waste heat recovery efficiency using fuel consumption data representing the fuel consumption of the fuel cell unit and the waste heat recovery amount, A device for calculating waste heat recovery efficiency, equipped with [specific features / features].

2. The pump includes a pulse motor, The rotational speed data includes the rotational speed instruction amount given to the pulse motor. A device for calculating the waste heat recovery efficiency according to claim 1.

3. The fuel consumption data includes current value data representing the magnitude of the current output from the fuel cell stack. A device for calculating the waste heat recovery efficiency according to claim 1.

4. The efficiency calculation unit calculates the fuel consumption from current value data representing the magnitude of the current output from the fuel cell stack. A device for calculating the waste heat recovery efficiency according to claim 1.

5. The rotational speed data and fuel consumption data are, respectively, data from a period during which the power generated by the fuel cell unit is above a predetermined value. A device for calculating the waste heat recovery efficiency according to claim 1.

6. The rotational speed data and fuel consumption data are, respectively, data from a period in which the amount of waste heat recovered per unit time is equal to or greater than a predetermined value. A device for calculating the waste heat recovery efficiency according to claim 1.

7. The waste heat recovery amount calculation unit calculates the waste heat recovery amount using the temperature difference between the temperature of the water before receiving the waste heat and the hot water generated by the waste heat. A device for calculating the waste heat recovery efficiency according to claim 1.

8. The aforementioned at least one fuel cell unit includes multiple fuel cell units, The efficiency calculation unit calculates the fuel consumption of each of the multiple fuel cell units by proportionally distributing the total fuel consumption of the fuel cell system according to the magnitude of the current output from the fuel cell stacks provided in each of the multiple fuel cell units. A device for calculating the waste heat recovery efficiency according to claim 1.

9. A method for calculating the waste heat recovery efficiency in a fuel cell system comprising at least one fuel cell unit, wherein the fuel cell unit includes a fuel cell stack. To acquire rotational speed data representing the rotational speed of a pump installed in a water path for recovering waste heat from the fuel cell stack in the form of hot water, The amount of waste heat recovered is calculated based on the aforementioned rotational speed data, The waste heat recovery efficiency is calculated using fuel consumption data representing the fuel consumption of the fuel cell unit and the amount of waste heat recovered. A method for calculating exhaust heat recovery efficiency, including [specific details omitted].

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