Method for evaluating energy efficiency of damp-heat test chamber

Abstract

The invention discloses a damp-heat test chamber energy efficiency evaluation method, which comprises the steps of setting a test working condition of an alternating damp-heat cycle of a test chamber, the test working condition comprising a plurality of working stages in the alternating damp-heat cycle and temperature and humidity change parameters of each working stage; putting the test sample into a test box or no-load, starting the test box, and carrying out an alternating damp-heat cycle test by the test box according to the test working condition; the actual total power consumption of the test box and the theoretical total energy calculated according to the collected temperature and humidity data are obtained through sorting after the test, and the stability weighted energy efficiency index of the test box is calculated according to the theoretical total energy and the actual total power consumption. Various energy consumption factors in the test process of the test box are comprehensively considered, the actual power consumption is combined, and the stability weighted energy efficiency index of the test box is calculated, so that the energy efficiency level and the performance level of the test box are scientifically and visually displayed, a basis is provided for a user to select an efficient and energy-saving test box, and the user experience is improved. And technical support is provided for manufacturers to improve product energy efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of test chamber energy efficiency testing, and in particular relates to a method for evaluating the energy efficiency of a damp heat test chamber. Background Art

[0002] Humidity test chambers are essential testing equipment in the fields of aviation, automobiles, home appliances, scientific research, etc. They are mainly used to simulate high temperature and high humidity and temperature and humidity cycle conditions to evaluate the environmental adaptability and reliability of electrical and electronic products. As the requirements for product quality in various industries continue to increase, the frequency and duration of use of test chambers have increased significantly, and their energy consumption issues have become a focus of industry attention. According to incomplete statistics, a standard volume (1~5m 3 ) The annual power consumption of a humidity test chamber can reach thousands of kilowatt-hours (usually 3000-8000kWh).

[0003] However, the current market lacks a unified, accurate, and scientific method for evaluating the energy efficiency of humidity and heat test chambers. Existing testing methods often only measure the chamber's power consumption and volume ratio, failing to comprehensively evaluate the chamber's energy conversion efficiency based on the test conditions specified in national standards. This makes it difficult for users to directly determine the chamber's energy efficiency level, hindering their ability to make informed decisions during equipment procurement and use. This also hinders manufacturers from optimizing and upgrading their products' energy efficiency, resulting in energy waste and inefficient resource utilization. Summary of the Invention

[0004] The main purpose of the present invention is to provide a method for evaluating the energy efficiency of a humidity test chamber, thereby overcoming the problem that the energy efficiency evaluation of existing humidity test chambers lacks a unified, accurate and scientific method.

[0005] To achieve the aforementioned object of the invention, the technical solution adopted by the present invention includes: a method for evaluating energy efficiency of a damp heat test chamber, comprising:

[0006] S1, setting a test chamber to perform an alternating damp heat cycle test condition, wherein the test condition includes multiple working stages in the alternating damp heat cycle and temperature and humidity change parameters of each working stage;

[0007] S2, placing the test sample into the test chamber or emptying the test chamber, and starting the test chamber, and performing the alternating damp heat cycle test in the test chamber according to the test conditions;

[0008] S3. After the test, the actual power consumption of each working stage of the test chamber and the theoretical energy calculated from the temperature and humidity data, as well as the actual total power consumption and the theoretical total energy of the test chamber are obtained. The stability weighted energy efficiency index of each working stage of the test chamber is calculated from the actual power consumption and theoretical energy of each working stage, and the total stability weighted energy efficiency index of the test chamber is calculated from the theoretical total energy and the actual total power consumption.

[0009] In a preferred embodiment, the multiple working stages include a pretreatment stage, a heating stage, a high-temperature constant temperature stage, a cooling stage, and a low-temperature constant temperature stage. The temperature and humidity change parameters of the pretreatment stage are: the temperature is 25°C ± 3K, the humidity is 50% RH, and the temperature is 25°C ± 3K and the humidity is 95% RH; the temperature and humidity change parameters of the heating stage are: the temperature is raised from 25°C ± 3K to 55°C ± 2K within 3h ± 30min, the humidity is not less than 95% RH, and cannot be less than 90% RH in the last 15min; the temperature and humidity change parameters of the high-temperature constant temperature stage are: the temperature is kept at Within 55℃±2K, until 12h+30min after the start of the cycle, and within the first 15min of this stage, the humidity is reduced to 90% RH by dehumidification, and within the last 15min, the humidity is increased to 95% RH by humidification. The humidity is not less than 90% RH at other times; the temperature and humidity change parameters of the cooling stage are: reducing the temperature from 55℃±2K to 25℃±3K within 3h~6h, and maintaining the humidity at not less than 95% RH; the temperature and humidity change parameters of the low-temperature constant temperature stage are: maintaining the temperature at 25℃±3K, and the humidity at not less than 95% RH, until the end of the cycle.

[0010] In a preferred embodiment, the pretreatment stage is divided into a heating or cooling stage and a humidification stage. The temperature change parameter of the heating or cooling stage is: the temperature reaches 25°C ± 3K and takes no more than 1 hour; the humidity change parameter of the humidification stage is: the humidity reaches between 95% RH and 100% RH and takes no more than 1 hour.

[0011] In a preferred embodiment, in S3, the process of obtaining the actual total power consumption of the test box includes: collecting the actual power consumption of each working stage in real time, and calculating the actual total power consumption from the sum of the actual power consumption of each stage.

[0012] In a preferred embodiment, in S3, the calculation method of the theoretical energy of the test chamber includes the enthalpy difference method, the ideal gas state equation method or the entropy increase method, and the process of calculating the theoretical total energy of the test chamber using the enthalpy method includes: calculating the unit wet air enthalpy change Δh in adjacent time intervals of each working stage, and then calculating it with the initial and final average air mass m of each working stage to obtain the overall wet air enthalpy change Q in adjacent time intervals of each working stage, and calculating the theoretical total energy from the sum of the overall wet air enthalpy change Q in adjacent time intervals of each working stage.

[0013] In a preferred embodiment, the calculation formula for the total wet air enthalpy change Q at the i-th moment in a certain working stage is:

[0014] Q i =Δhi m=Δh i ·ρ·V=Δh i ·(ρ i，1 +ρ i，2 ) / 2·V;

[0015] Where Δh i is the change in enthalpy of unit moist air at the i-th moment in a certain stage, in kJ / kg, m is the air mass, in kg, and ρ is the density of moist air, in kg / m 3 , V is the volume of the test chamber, in m 3 ,ρ i，1 is the density of moist air at the initial state point of a certain stage, ρ i，2 is the density of moist air at the final state point of a certain stage;

[0016] The change in unit wet air enthalpy at the i-th moment in the certain stage Δh i The calculation formula is:

[0017] Δh i =h i -h i-1 ;

[0018] Among them, h i is the unit enthalpy of moist air at the state point at the i-th moment in a certain stage, h i-1 is the unit moist air enthalpy value at the i-1th moment in a certain stage;

[0019] The unit enthalpy of moist air at the state point at time i in a certain stage h i The calculation formula is: i =1.005t i +0.001d i (2500+1.84t i );

[0020] Among them, t i is the temperature of the state point at the i-th moment in a certain stage, in °C, d i is the moisture content at the i-th moment in a certain stage, in g / kg;

[0021] The unit enthalpy of moist air at the state point at time i-1 in a certain stage h i-1 The calculation formula is: i-1 =1.005t i-1 +0.001d i-1 (2500+1.84t i -1);

[0022] Among them, t i-1 is the temperature of the state point at the i-1th moment in a certain stage, in °C, di-1 The moisture content of the state point at the i-1th moment in a certain stage, in g / kg

[0023] In a preferred embodiment, the calculation formula of the total stability weighted energy efficiency index of the test chamber is:

[0024]

[0025] Among them, SWEI is the stability weighted energy efficiency index, a dimensionless index; K is a normalization constant, which is 1 and the unit is kJ·kWh; E 总 The actual total power consumption of the test chamber in a certain working stage, in kWh; Q 总 The theoretical total energy calculated for the test chamber at the same working stage, in kJ;

[0026] The calculation formula of the theoretical total energy Qtotal calculated by the test chamber at a certain working stage is:

[0027]

[0028] Where i represents the time, n is an integer greater than or equal to 1, Q i Indicates the theoretical total energy calculated at the current moment, Q i-1 Represents the theoretical total energy calculated at the previous moment.

[0029] In a preferred embodiment, the test sample is an electronic and / or electrical product, and the electronic and / or electrical product includes an integrated circuit chip, a printed circuit board, or an automobile engine control unit.

[0030] In a preferred embodiment, in the process of obtaining the actual total power consumption of the test box, a power monitoring device is used to collect the actual power consumption data of each working stage in real time, and a data acquisition device is used to record it synchronously. At the same time, the temperature and humidity in the test box at each stage are also collected. After the test is completed, the actual power consumption data of each stage is exported and sorted from the data acquisition device. At the same time, the temperature and humidity values ​​in the test box at each stage are also collected, and the energy is calculated based on the collected temperature and humidity data.

[0031] In a preferred embodiment, in S2, a heating or cooling device and a humidifying device are used to heat or cool and humidify the air in the test box respectively. The heating or cooling device directly heats or cools the air in the test box, and the humidifying device humidifies the air in the test box by using a water vaporization humidification method.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides an energy efficiency evaluation scheme for a humidity and heat test chamber. By comprehensively considering various energy consumption factors during the test chamber testing process and combining them with actual power consumption, the Stability-Weighted Energy Efficiency Index (SWEI) of the test chamber as a whole and for each working stage is calculated. This scheme scientifically and intuitively displays its energy efficiency level, provides a basis for users to select energy-efficient test chambers, and offers technical support for manufacturers to improve product energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 1 is a flow chart of the energy efficiency evaluation method of the damp heat test chamber of the present invention;

[0036] Figure 2 It is a schematic diagram of temperature and humidity changes in various working stages of the alternating wet heat cycle of the test chamber of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be more fully understood through the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the present invention, which can be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as a basis for the claims and as a representative basis for teaching those skilled in the art to employ the present invention in various ways in virtually any appropriately detailed embodiment.

[0038] like Figure 1 As shown, the present invention discloses a method for evaluating the energy efficiency of a damp heat test chamber, which is used to accurately evaluate the energy conversion efficiency of the damp heat test chamber in a simulated alternating damp heat environment. The method specifically includes the following steps:

[0039] S1, setting a test chamber to perform a test condition of an alternating damp heat cycle, wherein the test condition includes multiple working stages in the alternating damp heat cycle and temperature and humidity change parameters of each working stage.

[0040] Specifically, during implementation, multiple operating stages of the humidity-alternating cycle test in the test chamber are set, along with temperature and humidity variation parameters for each operating stage. These temperature and humidity variation parameters include at least a set temperature value, a set humidity value, and the duration of each stage. In one embodiment, a humidity-alternating cycle in the test chamber is divided into five consecutive operating stages: a preconditioning stage, a temperature rise stage, a high-temperature constant temperature stage, a temperature drop stage, and a low-temperature constant temperature stage.

[0041] Among them, the temperature and humidity change parameters of the pretreatment stage are set as follows: the temperature is 25℃±3K and the humidity is 50% RH, and the temperature is humidified to 25℃±3K and 95% RH. Specifically, the pretreatment stage is divided into two stages, namely the heating or cooling stage and the humidification stage. Among them, the temperature change parameter of the heating or cooling stage is: the temperature reaches 25℃±3K and the time does not exceed 1 hour; the humidity change parameter of the humidification stage is: the humidity reaches between 95%RH and 100%RH and the time does not exceed 1 hour. It should be noted that the initial state point of this stage is the temperature of 25℃±3K and the humidity of 50%RH.

[0042] The temperature and humidity change parameters during the heating stage are set as follows: the temperature is raised from 25℃±3K to 55℃±2K within 3h±30min, the humidity is not less than 95%RH, and cannot be less than 90%RH in the last 15min.

[0043] The temperature and humidity change parameters of the high-temperature constant temperature stage are set as follows: the temperature is maintained within 55℃±2K until the end of 12h+30min from the start of the cycle, and within the first 15min of this stage, the humidity is reduced to 90%RH by dehumidification, and within the last 15min, the humidity is increased to 95%RH by humidification. The humidity is not less than 90%RH at other times.

[0044] The temperature and humidity change parameters in the cooling stage are set as follows: the temperature is reduced from 55℃±2K to 25℃±3K within 3h to 6h, and the humidity is maintained at no less than 95%RH.

[0045] The temperature and humidity change parameters of the low-temperature constant temperature stage are set as follows: maintaining the temperature at 25°C ± 3K and the humidity not less than 95% RH until the cycle (if one cycle is 24 hours, that is, until the 24-hour cycle) is completed.

[0046] In addition, test samples should be representative of electrical and electronic products. Their size, properties, and electrical load must meet standard requirements and not significantly affect the temperature and humidity conditions within the test chamber. Test samples include, but are not limited to, integrated circuit chips, printed circuit boards (PCBs), and automotive engine control units (ECUs). Alternatively, the test chamber can be empty, meaning no test samples are placed in it.

[0047] S2: Place the test sample in the test chamber or leave it empty and start the test chamber. The test chamber will be subjected to alternating damp heat cycle test according to the above test conditions.

[0048] Specifically, during this process, a heating device or cooling device and a humidifier are used to heat or cool and humidify the air in the test chamber, respectively, to achieve the temperature and humidity test conditions set in step S1. The heating device or cooling device directly heats or cools the air in the test chamber, while the humidifier humidifies the air in the test chamber using water vaporization humidification. The power consumption of heating the water is not considered, only the power consumption of the latent heat of water vaporization is considered.

[0049] S3. After the test, the actual power consumption of each working stage of the test chamber and the theoretical energy calculated from the temperature and humidity data, as well as the actual total power consumption and the theoretical total energy of the test chamber are obtained. The stability weighted energy efficiency index of each working stage of the test chamber is calculated from the actual power consumption and theoretical energy of each working stage, and the total stability weighted energy efficiency index of the test chamber is calculated from the theoretical total energy and the actual total power consumption.

[0050] Specifically, in step S3, the process of obtaining the actual total power consumption of the test chamber includes: using power monitoring equipment to collect the actual power consumption data of each working stage in real time, and using data acquisition equipment to record them synchronously, and after the test completes a 24-hour cycle, deriving and sorting the actual power consumption data of each stage from the data acquisition equipment, and calculating the actual total power consumption by the sum of the actual power consumption of each stage. For example, in the above-mentioned specific embodiment, an alternating wet heat cycle is divided into 5 working stages, excluding the pretreatment stage. In this step, the actual power consumption of the 4 working stages can be obtained. For example, the actual power consumption of the heating stage is defined as E2, the actual power consumption of the high temperature constant temperature stage is defined as E3, the actual power consumption of the cooling stage is defined as E4, and the actual power consumption of the low temperature constant temperature stage is defined as E5. The actual total power consumption is Etotal, then Etotal = E2+E3+E4+E5.

[0051] In step S3, the calculation method of the theoretical energy of the test chamber includes the enthalpy difference method, the ideal gas state equation method or the entropy increase method. The process of calculating the theoretical total energy of the test chamber using the enthalpy method includes: calculating the unit wet air enthalpy change Δh in the adjacent time intervals of each working stage, and then calculating it with the initial and final average air mass m of each working stage to obtain the overall wet air enthalpy change Q in the adjacent time intervals of each working stage, and calculating the theoretical total energy by the sum of the overall wet air enthalpy change Q in the adjacent time intervals of each working stage.

[0052] Among them, the calculation formula for the change in the total wet air enthalpy value Q at the i-th moment in a certain working stage is:

[0053] Q i =Δh i m=Δh i ·ρ·V=Δh i ·(ρ i，1 +ρ i，2 ) / 2·V;

[0054] Where Δh i is the change in enthalpy of unit moist air at the i-th moment in a certain stage, in kJ / kg, m is the air mass, in kg, and ρ is the density of moist air, in kg / m 3 , V is the volume of the test chamber, in m 3 ,ρ i，1 is the density of moist air at the initial state point of a certain stage, ρ i，2 is the density of moist air at the final state point of a certain stage;

[0055] The change in unit wet air enthalpy at the i-th moment in the certain stage Δh i The calculation formula is:

[0056] Δh i =h i -h i-1 ;

[0057] Among them, h i is the unit enthalpy of moist air at the state point at the i-th moment in a certain stage, h i-1 is the unit moist air enthalpy value at the i-1th moment in a certain stage;

[0058] The unit enthalpy of moist air at the state point at time i in a certain stage h i The calculation formula is: i =1.005t i +0.001d i (2500+1.84t i );

[0059] Among them, t i is the temperature of the state point at the i-th moment in a certain stage, in °C; di is the moisture content of the state point at the i-th moment in a certain stage, in g / kg;

[0060] The unit enthalpy of moist air at the state point at time i-1 in a certain stage h i-1 The calculation formula is: i-1 =1.005t i-1 +0.001d i-1 (2500+1.84t i-1 );

[0061] Among them, t i-1is the temperature of the state point at the i-1th moment in a certain stage, in °C, d i-1 It is the moisture content at the i-1th moment in a certain stage, in g / kg.

[0062] As in the above specific embodiment, an alternating wet heat cycle is divided into 5 working stages, excluding the pretreatment stage. In this step, according to the above calculation process, the total wet air enthalpy value change Q of the 4 working stages can be calculated in sequence. For example, the calculated total wet air enthalpy value change in the heating stage is defined as Q2, the total wet air enthalpy value change in the high temperature constant temperature stage is defined as Q3, the total wet air enthalpy value change in the cooling stage is defined as Q4, and the total wet air enthalpy value change in the low temperature constant temperature stage is defined as Q5. The theoretical total power consumption is Qtotal, which is the integral of the absolute value of the enthalpy difference within the cycle or the accumulation of the average fluctuation amplitude, such as Where i represents the time, n is an integer greater than or equal to 1, Qi represents the theoretical total energy calculated at the current time, Q i-1 Represents the theoretical total energy calculated at the previous moment.

[0063] The above parameters, such as the volume V of the test chamber, are obtained by measuring the internal dimensions of the test chamber. In addition, according to the set temperature and humidity requirements, the wet air density ρ, moisture content d and air mass m under various temperature and humidity conditions can be obtained by consulting the psychrometric chart.

[0064] Finally, the total stability-weighted energy efficiency index (SWEI) of the test chamber can be calculated using the following formula: the theoretical total energy Qtotal and the actual total power consumption Etotal obtained above are substituted into the following stability-weighted energy efficiency index formula:

[0065]

[0066] Among them, SWEI is the stability weighted energy efficiency index, a dimensionless index; K is a normalization constant, which is 1 and the unit is kJ·kWh; E 总 The actual total power consumption of the test chamber in a certain working stage, in kWh; Q 总 The theoretical total energy calculated for the test chamber at the same working stage, in kJ.

[0067] According to the calculation results, the energy efficiency level of the test chamber can be evaluated. The present invention adopts the stability weighted energy efficiency index (SWEI) to simultaneously reflect the control stability and energy efficiency of the test chamber, and intuitively reflect the energy efficiency level of the test chamber. If the SWEI is low, the energy consumption data of each stage is analyzed to find out the reasons for the high energy consumption, such as poor thermal insulation performance, low efficiency of the heating or cooling system, or optimization of the control algorithm to reduce the total Q, etc., to provide direction for subsequent improvements. The larger the SWEI value, the higher the energy efficiency level of the test chamber, and the stronger the ability of the test chamber to convert electrical energy into effective energy to achieve temperature and humidity changes.

[0068] Of course, it is also possible to calculate the stability-weighted energy efficiency index for each operating phase. This index is calculated based on the ratio of the theoretical energy Q to the actual power consumption E for each phase. The stability-weighted energy efficiency index for each phase can be used to measure the ability of a factory-produced test chamber to change temperature and humidity during each operating phase.

[0069] Of course, in addition to measuring the overall energy efficiency level of the test chamber and the energy efficiency level of each stage, the following capabilities of the test chamber can also be evaluated: cooling capacity, heating capacity, insulation capacity, dehumidification capacity, humidification capacity (electrical energy is converted into latent heat of vaporization of water), the ability of the equipment to adjust the temperature and humidity parameters quickly, and the ability to evaluate the stability of the equipment based on the temperature and humidity curve and temperature and humidity offset.

[0070] The following is a specific embodiment to illustrate the specific process of the energy efficiency evaluation method of the damp heat test chamber provided by the present invention.

[0071] Note: This embodiment uses four stages as examples. The calculation method is the same if the previous and next moments are considered.

[0072] First, a test chamber is provided. The chamber has a volume of V and is adiabatic, meaning there is no heat exchange with the outside world. The pressure inside the chamber, P, is constant at 1 standard atmosphere (i.e., P = 101325 Pa). The air inside the chamber is treated to change the temperature and humidity. The chamber is then maintained in a stable state under certain conditions (i.e., the entire process is under ideal conditions, ignoring energy losses). This is divided into five stages, combined with Figure 2 As shown:

[0073] Pretreatment stage: temperature is 25℃, humidity is 50%RH, humidification to 25℃, humidity is 95%RH.

[0074] Heating stage: The initial temperature and humidity are 25℃ and 95% RH respectively. The temperature is raised to 55℃ and the humidity is maintained at 95% RH. It takes 3h±30min.

[0075] High temperature constant temperature stage: the temperature is maintained at 55°C and the humidity is 90% RH, and is constant for 9 hours.

[0076] Cooling stage: The initial temperature and humidity are 55°C and 95% RH, and the temperature is lowered to 25°C and the humidity is maintained at 95% RH, which takes 3h to 6h.

[0077] Low temperature constant temperature stage: the temperature is maintained at 25 ° C and the humidity is maintained at 95% RH for 6 hours.

[0078] Except for the pretreatment stage, the theoretical total wet air enthalpy change Q of each stage is calculated through the above calculation process.

[0079] 1. Preprocessing stage:

[0080] The initial state point parameter values ​​of this stage are: t1 = 25°C, d1=9.88g / kg, ρ1=1.172kg / m 3 , m1=ρ1V=1.172Vkg. Here is the humidity at the initial state point of this stage.

[0081] The final state point of this stage has the following parameter values: t2 = 25°C, d2=19.05g / kg, ρ2=1.166kg / m 3 , m2=ρ2V=1.166Vkg. Here is the humidity at the final state point of this stage.

[0082] Since the room temperature during this stage is unknown, the power consumption during this stage is not calculated.

[0083] 2. Heating stage:

[0084] The initial state point parameter values ​​of this stage are: t1 = 25°C, d1=19.05g / kg, ρ1=1.166kg / m 3 , m1=ρ1V=1.166Vkg.

[0085] The final state point of this stage has the following parameter values: t2 = 55°C, d2=107.83g / kg, ρ2=1.011kg / m 3 , m2=ρ2V=1.011Vkg.

[0086] Then the unit wet air enthalpy value h1 at the initial state point of this stage is:

[0087] h1=1.005t1+0.001d1(2500+1.84t1)=1.005×25+0.001×19.05(2500+1.84×25)=73.626kJ / kg.

[0088] The unit moist air enthalpy value h2 at the final state point of this stage is:

[0089] h2=1.005t2+0.001d2(2500+1.84t2)=1.005×55+0.001×107.83(2500+1.84×55)

[0090] =335.762kJ / kg.

[0091] The change in unit enthalpy of wet air Δh during this stage is:

[0092] Δh=h2-h1=262.136kJ / kg.

[0093] Therefore, the total wet air enthalpy change Q2 in this stage is:

[0094] Q2=m·Δh=(ρ1+ρ2) / 2·V·Δh=(1.166+1.011)V / 2×262.136=285.335VkJ.

[0095] 3. High temperature constant temperature stage:

[0096] This stage is divided into three stages: dehumidification stage, constant temperature stage and humidification stage;

[0097] The dehumidification stage is within the first 15 minutes of this stage, and the initial state point parameter values ​​are: t1 = 55 ° C, d1=107.83g / kg, ρ1=1.011kg / m 3 , m1=ρ1V=1.011Vkg.

[0098] The final state point of this stage has the following parameter values: t2 = 55°C, d2=101.23g / kg, ρ2=1.014kg / m 3 , m2=ρ2V=1.014Vkg.

[0099] Then the change in unit enthalpy of wet air Δh in this stage is:

[0100] Δh=h2-h1=0.001(2500+1.84t)×(d2-d1)=0.001(2500+1.84×55)×|101.23-107.83|=17.168kJ / kg.

[0101] Therefore, the total enthalpy change of wet air in this stage is Q1′:

[0102] Q1′=m·Δh=(ρ1+ρ2) / 2·V·Δh=(1.014+1.011)V / 2×17.168k=17.382VkJ.

[0103] The constant temperature stage is a 3-hour constant temperature stage in the middle of this stage. This process does not consume energy in the theoretical calculation stage, that is, Q=0.

[0104] The humidification stage is the last 15 minutes of this stage, and the initial state point parameter values ​​are: t1 = 55 ° C, d1=101.23g / kg, ρ1=1.014kg / m 3 , m1=ρ1V=1.014Vkg.

[0105] The final state point of this stage has the following parameter values: t2 = 55°C, d2=107.83gg / kg, ρ2=1.011kg / m 3 , m2=ρ2V=1.011Vkg.

[0106] Then the change in unit enthalpy of wet air Δh in this stage is:

[0107] Δh=h2-h1=0.001(2500+1.84t)×(d2-d1)=0.001(2500+1.84×55)×107.83-101.23=17.168kJ / kg.

[0108] Therefore, the total wet air enthalpy change Q2' in this stage is:

[0109] Q2′=m·Δh=(ρ1+ρ2) / 2·V·Δh=(1.014+1.011)V / 2×17.168k=17.382VkJ.

[0110] Therefore, the total enthalpy change of wet air in the high temperature constant temperature stage is Q3 = Q1' + Q2' = 34.764 VkJ.

[0111] 4. Cooling stage:

[0112] The initial state point parameter values ​​of this stage are: h = 55 ° C, d1=107.83g / kg, ρ1=1.011kg / m 3 , m1=ρ1V=1.011Vkg.

[0113] The final state point of this stage has the following parameter values: t2 = 25°C, d2=19.05g / kg, ρ2=1.166kg / m 3 , m2=ρ2V=1.166Vkg.

[0114] Then the unit wet air enthalpy value h1 at the initial state point of this stage is:

[0115] h1=1.005t1+0.001d1(2500+1.84t1)=1.005×55+0.001×107.83(2500+1.84×55)

[0116] =335.762kJ / kg.

[0117] The unit moist air enthalpy value h2 at the final state point of this stage is:

[0118] h2=1.005t2+0.001d2(2500+1.84t2)=1.005×25+0.001×19.05(2500+1.84×25)=73.626kJ / kg.

[0119] The change in unit enthalpy of wet air Δh during this stage is:

[0120] Δh=|h2-h1|=262.136kJ / kg.

[0121] Therefore, the total wet air enthalpy change Q4 in this stage is:

[0122] Q4=m·Δh=(ρ1+ρ2) / 2·V·Δh=(1.166+1.011)V / 2×262.136=285.335VkJ.

[0123] 5. Low temperature constant temperature stage:

[0124] It should be noted that in theoretical calculations, the energy loss of the test chamber to the outside world is not considered, so the test chamber does not consume energy when maintaining a stable state. Therefore, the theoretical calculation is not related to time, and the energy consumption comes entirely from the changes in temperature and humidity inside the test chamber.

[0125] Therefore, in this stage, since the entire process is in an adiabatic state, no energy is consumed, that is, Q5=0.

[0126] Therefore, in this embodiment, the theoretical total power consumption Qtotal=Q2+Q3+Q4+Q5=285.335+34.764+285.335+0=605.434 VkJ.

[0127] Of course, there are many ways to calculate theoretical power consumption. In addition to the above-mentioned enthalpy difference method, two other methods are listed below: the ideal gas state equation method and the entropy increase method.

[0128] Ideal gas state equation method:

[0129] 1. Preprocessing stage

[0130] Conditions: 25°C, 50% relative humidity → 25°C, 95% relative humidity;

[0131] ①Calculate moisture content:

[0132] Saturated water vapor pressure P at 25℃ sat =3169Pa, the moisture content calculation formula is as follows:

[0133]

[0134] Where, Represents relative humidity, B represents standard atmospheric pressure, and its value is 101325Pa;

[0135] ② Air quality calculation:

[0136] Ideal gas state equation: PV = m air RT;

[0137] Among them, P represents the absolute pressure of the gas, V represents the total volume of the gas, m air is the total mass of the gas, and R is the gas constant, which is 287 Jkg -1 K -1 , T is the thermodynamic temperature of the gas;

[0138] Air quality

[0139] 2. Heating stage

[0140] Conditions: 25°C, 95% relative humidity → 55°C, 95% relative humidity;

[0141] ① Calculation of air sensible heat:

[0142] Q 2a =m air c p ΔT=1.184V×1.005×30=35.698VkJ;

[0143] ② Calculation of sensible heat of water vapor:

[0144] Saturated water vapor pressure P at 25℃ sat =3169Pa, saturated water vapor pressure P at 55℃ sat =15752Pa;

[0145] Initial moment:

[0146] Final Moment:

[0147] Water vapor mass Δm v =m v，2 -m v，1 =1.184V×(0.103-0.0188)=0.0997Vkg;

[0148] Q 2b =Δm v c p，v ΔT=0.0997V×1.86×30=5.56VkJ;

[0149] ③ Calculation of latent heat of water vapor:

[0150] Q 2c =m v，2 r2-m v，1 r1=0.122V×2370-0.0223V×2442=234.683VkJ;

[0151] ③ Calculation of total energy consumption:

[0152] Q2=Q 2a +Q 2b +Q 2c =35.698V+5.562V+234.683V=275.943VkJ.

[0153] 3. Dehumidification stage

[0154] Conditions: 55°C, 95% relative humidity → 55°C, 90% relative humidity;

[0155] ① Calculation of dehumidification capacity:

[0156] Saturated water vapor pressure P at 55℃ sat =15752Pa;

[0157] Initial moment: Final Moment:

[0158] ②Theoretical dehumidification energy consumption:

[0159] Q3=m air (d2-d3)r=1.184V×0.005×2370=14.03VkJ;

[0160] (where r = 2370 kJ / kg is the latent heat of vaporization of water at 55°C).

[0161] 4. High temperature constant temperature stage

[0162] Conditions: Maintain 55°C, 90% relative humidity;

[0163] Theoretical energy consumption:

[0164] Under adiabatic conditions, the constant temperature process does not require energy consumption, Q4=0.

[0165] 5. Humidification stage

[0166] Conditions: 55°C, 90% relative humidity → 55°C, 95% relative humidity;

[0167] ①Calculation of humidification capacity:

[0168] Saturated water vapor pressure P at 55℃ sat =15752Pa;

[0169] Initial moment: Final Moment:

[0170] ②Theoretical humidification energy consumption:

[0171] Q5=m air (d5-d4)r=1.184V×0.005×2370=14.03VkJ;

[0172] Among them, r = 2370kJ / kg is the latent heat of vaporization of water at 55°C.

[0173] 6. Cooling stage

[0174] Conditions: 55°C, 95% relative humidity → 25°C, 95% relative humidity;

[0175] ① Calculation of air sensible heat:

[0176] Q 6a =m air c p ΔT=1.184V×1.005×30=35.698VkJ;

[0177] ② Calculation of sensible heat of water vapor:

[0178] Saturated water vapor pressure P at 25℃ sat =3169Pa, saturated water vapor pressure P at 55℃ sat =15752Pa;

[0179] Initial moment:

[0180] Final Moment:

[0181] Water vapor mass change Δm v =m v，5 -m v，6 =1.184V×(0.103-0.0188)=0.0997Vkg;

[0182] Q 6b =Δm v c p，v ΔT=0.0997V×1.86×30=5.56VkJ;

[0183] ③ Calculation of latent heat of water vapor:

[0184] Q 6c =m v，2 r2-m v，1r1=0.122V×2370-0.0223V×2442=234.683VkJ;

[0185] ③ Calculation of total energy consumption:

[0186] Q6=Q 6a +Q 6b +Q 6c =35.698V+5.562V+234.683V=275.943VkJ;

[0187] Theoretical total power consumption:

[0188] Q=Q2+Q3+Q4+Q5+Q6=275.943V+14.03V+14.03V+275.943V=579.946VkJ

[0189] =0.1612kWh.

[0190] Entropy increase method:

[0191] 1. Heating process

[0192] Conditions: 25°C, 95% relative humidity → 55°C, 95% relative humidity;

[0193] ① Dry air entropy change:

[0194]

[0195] ② Water vapor entropy change:

[0196] 25℃s v，1 =8.556kJ / (kg·K);

[0197] 55℃s v，2 =8.901kJ / (kg·K);

[0198] ΔS air =0.0997×1.184V×(8.901-8.558)+0.0105×1.184V×8.901=1.058VkJ / K;

[0199] ΔS2=0.114V+1.058=1.172kJ / K;

[0200] Q2=TΔS V =298.15×1.172V=349.432VkJ;

[0201] 2. Dehumidification stage

[0202] ①Moisture content changes:

[0203] Initial moment:

[0204] Final Moment:

[0205] Water vapor mass change Δm v =m v，2 -m v，3 =1.184V×(0.0103-0.098)=0.0059Vkg;

[0206] ② Entropy change calculation:

[0207] 55℃ saturated water vapor g =8.901kJ / (kg·K), liquid water s f =0.703kJ / (kg·K);

[0208] ΔS v =0.0059V×(0.703-8.901)=-0.0484kJ / K;

[0209] ③Theoretical energy consumption:

[0210] Q3=T|ΔS v |=298.15×0.0484V=14.430VkJ;

[0211] 3. High temperature constant temperature stage

[0212] Conditions: Maintain 55°C, 90% relative humidity;

[0213] Theoretical energy consumption:

[0214] Under adiabatic conditions, the constant temperature process does not require energy consumption, Q4 = 0;

[0215] 4. Humidification stage

[0216] Conditions: 55°C, 90% relative humidity → 55°C, 95% relative humidity;

[0217] Reverse Operation Phase 3

[0218] ΔS v =0.0059V×(0.703-8.901)=-0.0484kJ / K;

[0219] Q5=T|ΔS v |=298.15×0.0484V=14.430VkJ;

[0220] 5. Cooling down phase

[0221] Conditions: 55°C, 95% relative humidity → 25°C, 95% relative humidity;

[0222] Reverse Operation Phase 2

[0223] ΔS6=0.114V+1.058=1.172kJ / K;

[0224] Q6=TΔS v =298.15×1.172V=349.432VkJ;

[0225] Theoretical total power consumption:

[0226] Q=Q2+Q3+Q4+Q5+Q6=26.804V+349.432V+14.43V+14.43V+349.432V=

[0227] 727.724VkJ.

[0228] From the above calculation processes, we can see that different calculation methods will produce different results. For engineering applications, the enthalpy difference method is preferred because it is easy to calculate, obtains data quickly, and produces high-precision results.

[0229] In addition, the actual total power consumption Etotal is obtained through the process in the above step S3.

[0230] In summary, the stability weighted energy efficiency index of the test chamber can be obtained

[0231] There is a machine with a capacity of 1m 3 Temperature and humidity test chamber, the actual measured data are shown in Tables 1 to 4.

[0232] Table 1 Data collection table for the heating stage

[0233]

[0234]

[0235] The data from 2:00:06 to 4:59:55 are omitted. The energy and power consumption during the heating phase are calculated according to the above formula:

[0236]

[0237] E 升 =4139.919922-4131.959961=7.959961kWh.

[0238] Table 2 Data collection table for high temperature constant temperature stage

[0239]

[0240] The data from 5:00:05 to 14:59:55 are omitted. The high temperature constant temperature energy and power consumption are calculated according to the above formula:

[0241]

[0242] E 高恒 =4142.517985-4139.919922=2.598063kWh.

[0243] Table 3 Data collection table for cooling stage

[0244]

[0245] The data from 15:00:05 to 19:59:55 are omitted. The cooling energy and power consumption are calculated according to the above formula:

[0246] E 降 =4188.362712-4142.517985=45.844727kWh.

[0247] Table 4 Data collection table of low temperature constant temperature stage

[0248]

[0249] The data from 20:00:05 to 23:59:55 are omitted. The cooling energy and power consumption are calculated according to the above formula:

[0250] E 低i =4201.091309-4188.362712=12.728597kWh.

[0251] so:

[0252] Qtotal=611.23kJ+49.232kJ+294.336kJ+20.353kJ=975.151;

[0253] Total E=7.959961kWh+2.598063kWh+45.844727kWh+12.728597kWh=69.131348;

[0254] According to the formula Calculate the stability weighted energy efficiency index of the test chamber:

[0255]

[0256] It should be noted that the working conditions in the above preferred embodiment can also be changed according to the different test requirements of different products, including special requirements such as high temperature, high humidity, sub-zero and extreme temperatures. As long as the temperature and humidity are changed unidirectionally at each stage of the entire test process and the temperature and humidity can be recorded in real time, the above enthalpy difference method can be used for calculation.

[0257] A method for evaluating the energy efficiency of a damp heat test chamber provided by an embodiment of the present invention has at least the following advantages: the present invention provides an energy efficiency evaluation scheme for a damp heat test chamber, which comprehensively considers various energy consumption factors during the test chamber testing process and combines the actual power consumption to calculate the stability-weighted energy efficiency index of the test chamber in total and in each working stage, thereby scientifically and intuitively displaying its energy efficiency level, providing a basis for users to select energy-efficient test chambers, and also providing technical support for manufacturers to improve product energy efficiency.

[0258] The various aspects, embodiments, features and examples of the present invention should be considered as illustrative in all respects and are not intended to limit the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0259] The use of headings and sections in this disclosure is not meant to limit the disclosure; each section may apply to any aspect, embodiment, or feature of the disclosure.

Claims

1. A method for evaluating energy efficiency of a damp heat test chamber, characterized by: The method comprises: S1, setting a test chamber to perform an alternating damp heat cycle test condition, wherein the test condition includes multiple working stages in the alternating damp heat cycle and temperature and humidity change parameters of each working stage; S2, placing the test sample into the test chamber or emptying the test chamber, and starting the test chamber, and performing the alternating damp heat cycle test in the test chamber according to the test conditions; S3. After the test, the actual power consumption of each working stage of the test chamber and the theoretical energy calculated from the temperature and humidity data, as well as the actual total power consumption and the theoretical total energy of the test chamber are obtained. The stability weighted energy efficiency index of each working stage of the test chamber is calculated from the actual power consumption and theoretical energy of each working stage, and the total stability weighted energy efficiency index of the test chamber is calculated from the theoretical total energy and the actual total power consumption.

2. The method for evaluating energy efficiency of a damp heat test chamber according to claim 1, wherein: The multiple working stages include a pretreatment stage, a heating stage, a high-temperature constant temperature stage, a cooling stage, and a low-temperature constant temperature stage. The temperature and humidity change parameters of the pretreatment stage are: the temperature is 25°C ± 3K, the humidity is 50% RH, and the temperature is humidified to 25°C ± 3K and the humidity is 95% RH; the temperature and humidity change parameters of the heating stage are: the temperature is raised from 25°C ± 3K to 55°C ± 2K within 3h ± 30min, the humidity is not less than 95% RH, and cannot be less than 90% RH in the last 15min; the temperature and humidity change parameters of the high-temperature constant temperature stage are: the temperature is maintained at 55°C ±2K, until the end of 12h+30min after the start of the cycle, and within the first 15min of this stage, the humidity is reduced to 90% RH by dehumidification, and within the last 15min, the humidity is increased to 95% RH by humidification, and the humidity is not less than 90% RH at other times; the temperature and humidity change parameters of the cooling stage are: the temperature is reduced from 55℃±2K to 25℃±3K within 3h~6h, and the humidity is maintained at not less than 95% RH; the temperature and humidity change parameters of the low-temperature constant temperature stage are: maintain the temperature at 25℃±3K, and the humidity is not less than 95% RH until the end of the cycle.

3. The method for evaluating energy efficiency of a damp heat test chamber according to claim 2, wherein: The pretreatment stage is divided into a heating or cooling stage and a humidification stage. The temperature change parameter of the heating or cooling stage is: the temperature reaches 25°C ± 3K and the time does not exceed 1 hour; the humidity change parameter of the humidification stage is: the humidity reaches between 95% RH and 100% RH and the time does not exceed 1 hour.

4. The method for evaluating energy efficiency of a damp heat test chamber according to claim 1, wherein: In S3, the process of obtaining the actual total power consumption of the test box includes: collecting the actual power consumption of each working stage in real time, and calculating the actual total power consumption from the sum of the actual power consumption of each stage.

5. The method for evaluating energy efficiency of a damp heat test chamber according to claim 1, wherein: In S3, the calculation method of the theoretical energy of the test chamber includes the enthalpy difference method, the ideal gas state equation method or the entropy increase method. The process of calculating the theoretical total energy of the test chamber using the enthalpy method includes: calculating the unit wet air enthalpy change Δh in the adjacent time intervals of each working stage, and then calculating it with the initial and final average air mass m of each working stage to obtain the overall wet air enthalpy change Q in the adjacent time intervals of each working stage, and calculating the theoretical total energy from the sum of the overall wet air enthalpy change Q in the adjacent time intervals of each working stage.

6. The method for evaluating energy efficiency of a damp heat test chamber according to claim 5, wherein: The calculation formula for the total wet air enthalpy change Q at the i-th moment in a certain working stage is: Q i =Δh i ·m=Δh i ·ρ·V=Δh i ·(ρ i，1 +ρ i，2 ) / 2·V; Where Δh i is the change in enthalpy of unit moist air at the i-th moment in a certain stage, in kJ / kg, m is the air mass, in kg, and ρ is the density of moist air, in kg / m 3 , V is the volume of the test chamber, in m 3 ,ρ i，1 is the density of moist air at the initial state point of a certain stage, ρ i，2 is the density of moist air at the final state point of a certain stage; The change in unit wet air enthalpy at the i-th moment in the certain stage Δh i The calculation formula is: Δh i =h i -h i-1 ; Among them, h i is the unit enthalpy of moist air at the state point at the i-th moment in a certain stage, h i-1 is the unit moist air enthalpy value at the i-1th moment in a certain stage; The unit enthalpy of moist air at the state point at time i in a certain stage h i The calculation formula is: i =1.005t i +0.001d i (2500+1.84t i ); Among them, t i is the temperature of the state point at the i-th moment in a certain stage, in °C, d i is the moisture content at the i-th moment in a certain stage, in g / kg; The unit enthalpy of moist air at the state point at time i-1 in a certain stage h i-1 The calculation formula is: i-1 =1.005t i-1 +0.001d i-1 (2500+1.84t i-1 ); Among them, t i-1 is the temperature of the state point at the i-1th moment in a certain stage, in °C, d i-1 It is the moisture content at the i-1th moment in a certain stage, in g / kg.

7. The method for evaluating energy efficiency of a damp heat test chamber according to claim 6, wherein: The calculation formula of the total stability weighted energy efficiency index of the test chamber is: Among them, SWEI is the stability weighted energy efficiency index, a dimensionless index; K is a normalization constant, which is 1 and the unit is kJ·kWh; E 总 The actual total power consumption of the test chamber in a certain working stage, in kWh; Q 总 The theoretical total energy calculated for the test chamber at the same working stage, in kJ; The calculation formula of the theoretical total energy Qtotal calculated by the test chamber at a certain working stage is: Where i represents the time, n is an integer greater than or equal to 1, Q i Indicates the theoretical total energy calculated at the current moment, Q i-1 Represents the theoretical total energy calculated at the previous moment.

8. The method for evaluating energy efficiency of a damp heat test chamber according to claim 1, wherein: The test samples are electronic and / or electrical products, including integrated circuit chips, printed circuit boards or automobile engine control units.

9. The method for evaluating energy efficiency of a damp heat test chamber according to claim 4, wherein: In the process of obtaining the actual total power consumption of the test box, the power monitoring equipment is used to collect the actual power consumption data of each working stage in real time, and the data acquisition equipment is used to record it synchronously. After the test is completed, the actual power consumption data of each stage is exported and sorted from the data acquisition equipment. At the same time, the temperature and humidity values ​​in the test box at each stage are also collected, and the energy is calculated based on the collected temperature and humidity data.

10. The method for evaluating energy efficiency of a damp heat test chamber according to claim 1, wherein: In S2, a heating or cooling device and a humidifying device are used to heat or cool and humidify the air in the test box respectively. The heating or cooling device directly heats or cools the air in the test box, and the humidifying device humidifies the air in the test box by using a water vaporization humidification method.

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