A new energy vehicle heat balance test method and system

Abstract

This invention specifically relates to a thermal balance testing method and system for new energy vehicles, encompassing the field of thermodynamics and fluid measurement technology. It includes: a humid and cold environment and intake boundary simulation module; a miniaturized wind tunnel module for measuring air-side enthalpy difference; a refrigerant-side thermal balance cross-verification module; a defrosting phase change physical measurement and calibration module; and a calculation and control host computer module. In this invention, the sensor topology and fundamental thermodynamic laws are strongly coupled at the hardware level. By hard-coding the standard humid air property equation within an independent computing chip, absolute physical separation of sensible heat and latent heat is achieved. Simultaneously, the real-world state of the refrigerant side is acquired, and the heat transfer on the refrigerant side is compared in real-time with the heat transfer on the air side captured by the miniaturized wind tunnel. When the energy deviation between the two ends deviates from the preset thermal balance safety margin, the system immediately intercepts and triggers a self-check to address the implicit errors caused by a single test side.

Description

Technical Field

[0001] This invention relates to the field of thermodynamic and fluid measurement technology, and in particular to a method and system for testing the thermal balance of new energy vehicles. Background Technology

[0002] In the development and testing of heat pump systems for new energy vehicles, frosting and fogging conditions in humid and cold environments have a significant impact on the performance of heat pumps. Accurate measurement of latent heat is the core of evaluating heat pump energy efficiency and formulating defrosting strategies.

[0003] However, existing heat pump test benches and testing methods have the following drawbacks: Existing environmental chambers generally use single-chamber or single-duct control, resulting in poor temperature and humidity uniformity. The humidification process often uses ultrasonic humidification, which generates 1~5μm liquid water droplets that directly adhere to the surface of the heat exchanger fins, leading to a serious overestimation of latent heat measurement. At the same time, sampling pipelines without precise heat tracing are prone to condensation or even frost blockage under low-temperature conditions. Existing wind speed measurements mostly use hot-wire anemometers, which are prone to failure due to ice cover under frosting conditions; and temperature and humidity sampling is mostly single-point or few-point measurement, which cannot truly reflect the extremely uneven flow field state of heat exchanger outlet.

[0004] Therefore, a thermal balance testing method and system for new energy vehicles is proposed to address the aforementioned problems. Summary of the Invention

[0005] The purpose of this invention is to provide a thermal balance testing method and system for new energy vehicles in order to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A thermal balance testing system for new energy vehicles, comprising: The humid and cold environment and intake boundary simulation module is configured to include an external environment simulation chamber and a passenger compartment environment simulation chamber; the simulation chamber is connected to a saturated steam humidification array and outputs humid air; The air-side enthalpy difference miniature measurement wind tunnel module is configured to be connected to the anti-condensation heat tracing pipeline. The main body of the module is a miniature wind tunnel, and the miniature wind tunnel is equipped with the following components in sequence along the airflow direction: cross-sectional temperature and humidity sampling grid at the air inlet, heat exchanger under test, cross-sectional temperature and humidity sampling grid at the air outlet, anti-disturbance Pitot tube flow meter array, and air state isolator. The refrigerant-side heat balance cross-verification module is configured to acquire the refrigerant status and calculate the refrigerant-side heat exchange, so as to form an energy verification with the heat exchange measured on the air side. The defrosting phase change physics measurement and calibration module is configured to be installed below the heat exchanger under test to measure the mass of liquid water produced during defrosting, which serves as the calibration benchmark for latent heat measurement. The host computer module for calculation and control is configured to calculate the latent heat exchange and trigger the defrosting action through a defrosting trigger when the inlet and outlet pressure difference and the proportion of latent heat exchange meet the preset physical threshold conditions.

[0007] Preferably, the humid and cold environment and intake boundary simulation module includes a dual dew point micro-pressure environment chamber, which is a completely physically isolated external environment simulation chamber and passenger compartment environment simulation chamber; Multiple sampling units are arranged in different sections of the simulation cavity, and the system takes the average value of the measurements from multiple sampling units as the feedback value for temperature and humidity control. The simulation chamber is also equipped with a micro-pressure control module, whose control objective is to maintain the internal pressure of the chamber above the external atmospheric pressure by a preset positive pressure threshold.

[0008] Preferably, the humid and cold environment and intake boundary simulation module further includes a purely physical saturated steam humidification array and an anti-condensation heat tracing pipeline; The pure physical saturated steam humidification array includes an isothermal electrode steam humidifier, whose output steam flows sequentially through a first-stage diffusion chamber with distribution holes and a second-stage static mixer containing cross-arranged corrugated plates. The outer wall of the anti-condensation heat tracing pipeline is equipped with an electric heat tracing cable, and a cold mirror dew point meter is installed at its inlet to measure the dew point temperature of the air inside the pipeline in real time, so as to control the pipeline wall temperature to always be higher than the preset safe temperature difference of the dew point temperature.

[0009] Preferably, the main body of the air-side enthalpy difference miniature measurement wind tunnel module is a miniature wind tunnel with an adjustable cross-section, and its interior is equipped with independent inlet cross-section temperature and humidity sampling grids and outlet cross-section temperature and humidity sampling grids respectively. The distance between the sampling grid and the heat exchanger under test is set proportionally to the equivalent diameter of the wind tunnel section. The sampling grid is evenly distributed with sampling units including platinum resistance thermometers and high-frequency cold mirror dew point meters at a preset density. The temperature sensing probe of the sampling unit extends into the center of the wind tunnel channel.

[0010] Preferably, the air-side enthalpy difference miniaturized measurement wind tunnel module further includes an anti-disturbance Pitot tube flowmeter array and an air state isolator; The anti-disturbance Pitot tube flow meter array uses a preset number of S-shaped averaging pitot tubes spanning the cross section of the wind tunnel, with dynamic pressure taps and static pressure taps spaced apart along the axial direction for each Pitot tube. The air state isolator is located downstream of the Pitot tube at the air outlet. It is an insulated mixing chamber with an enlarged cross-sectional area and contains cross-arranged static mixing baffles.

[0011] Preferably, the refrigerant-side thermal balance cross-verification module includes a Coriolis mass flow meter and an immersion thermodynamic probe; The Coriolis mass flow meter is connected in series in the high-pressure and low-pressure pipelines of the heat pump under test, and is equipped with a heat tracing structure. The immersion thermodynamic probe is a combination probe that integrates an armored thermocouple and a pressure transmitter. Its temperature sensing head and the side pressure tap without a pressure tapping tube extend directly into the refrigerant pipeline to contact the actual fluid.

[0012] Preferably, the refrigerant-side thermal balance cross-validation module runs thermal balance cross-validation logic: The refrigerant specific enthalpy is determined by querying a hard-coded standard refrigerant property database based on real-time refrigerant temperature and pressure measured by probe, and the heat exchange on the high-pressure side and low-pressure side is calculated by combining the mass flow rate. When the calculated refrigerant-side heat exchange rate deviates from the total heat exchange rate calculated on the air side by more than the preset heat balance cross-validation deviation ratio, a system alarm is triggered.

[0013] Preferably, the defrosting phase change physical measurement and calibration module includes a flow-guiding constant temperature water receiving tray and a micro-weighing system; The bottom of the flow-guiding constant temperature water receiving tray is set with an inclined angle and a flow-guiding groove, and a constant temperature heating wire is embedded inside to keep the water receiving tray in a preset non-freezing and anti-evaporation temperature range. The micro-weighing system includes a high-precision electronic balance housed inside a sealed windproof cover. The windproof cover is equipped with temperature and pressure sensors to obtain air density and to compensate for and correct the weighing results of the balance by air buoyancy.

[0014] Preferably, the solver based on pure thermodynamic rules calculates the absolute humidity and the enthalpy of moist air based on the measured dry-bulb temperature and dew point temperature, and on the hard-coded standard saturated vapor pressure equation and state equation. The separation operator dynamically calculates the isobaric specific heat of moist air based on real-time absolute humidity to solve for the sensible heat transfer, and obtains the determined latent heat transfer by subtracting the sensible heat transfer from the total heat transfer based on the first law of thermodynamics. It also includes defrost triggers based on physical thresholds: The defrost trigger uses a dual physical threshold AND logic: it monitors in real time the rise rate of the static pressure difference between the inlet and outlet air relative to the initial reference value, as well as the decrease rate of the latent heat transfer rate as a percentage of the total heat transfer rate. Only when the rise rate is greater than the first preset physical threshold and the decrease rate is greater than the second preset physical threshold, a defrost command is sent to the heat pump under test.

[0015] A method for thermal balance testing of new energy vehicles, comprising: The target temperature and humidity conditions are reproduced by the humid and cold environment and air intake boundary simulation module. Pure gaseous humid air without liquid droplets is output to the heat pump under test through the pure physical saturated steam humidification array and anti-condensation heat tracing pipeline. The air-side enthalpy difference miniaturized measurement wind tunnel module is used to obtain the air physical state and flow velocity before and after heat exchange in real time; the calculation and control host computer module calls the air specific enthalpy hard-coded solver and the latent heat / sensible heat separation operator to separate the total heat exchange and latent heat exchange on the air side. Run the refrigerant-side heat balance cross-verification module to obtain the physical state of the refrigerant and calculate the heat exchange on the refrigerant side; compare the heat exchange on the refrigerant side with the total heat exchange on the air side, and if the deviation exceeds the preset physical verification threshold range, trigger an abnormal alarm to eliminate the single-sided measurement error; When the pressure difference between the inlet and outlet of the heat exchanger increases and the proportion of latent heat transfer decreases, meeting the preset physical threshold conditions, a defrosting trigger based on the physical threshold sends a defrosting command to the heat pump under test. During defrosting, the defrosting phase change physical metering and calibration module is used to weigh the defrosting water and obtain the absolute value of the latent heat of phase change. This absolute value is then used to physically calibrate the latent heat transfer.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention achieves absolute physical separation of sensible heat and latent heat by strongly coupling sensor topology with the fundamental laws of thermodynamics at the hardware level and by hard-coding the standard humid air property equation within an independent computing chip. At the same time, it introduces the acquisition of the real state of the refrigerant side and compares the heat exchange of the refrigerant side with the heat exchange of the air side captured by the miniature wind tunnel in real time. When the energy deviation between the two ends deviates from the preset thermal balance safety margin, the system immediately intercepts and triggers a self-test to deal with the implicit error caused by a single test side.

[0017] 2. This invention uses isothermal steam humidification combined with multi-stage dynamic rectification, supplemented by an all-path anti-condensation adaptive heat tracing pipeline, to ensure a continuous supply of pure gaseous humid air without liquid water entrainment to the test object, thus purifying the intake airflow field; by arranging a water receiving tray with a constant temperature flow guiding structure at the bottom of the heat exchanger and a micro-weighing system with integrated air buoyancy compensation, the direct extraction of the true mass of phase change water is realized. Attached Figure Description

[0018] Further details, features, and advantages of this application are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which: Figure 1 This is a system structure diagram of the present invention; Figure 2 This is a flowchart of the method of the present invention. Detailed Implementation

[0019] Several embodiments of this application will now be described in more detail with reference to the accompanying drawings to enable those skilled in the art to implement this application. This application may be embodied in many different forms and for various purposes and should not be limited to the embodiments set forth herein. These embodiments are provided to make this application thorough and complete, and to fully convey the scope of this application to those skilled in the art. The embodiments described do not limit this application.

[0020] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It will be further understood that terms such as those defined in commonly used dictionaries shall be interpreted as having a meaning consistent with their meaning in the relevant field and / or the context of this specification, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0021] Example 1 Its specific implementation method is combined with the appendix Figure 1 and attached Figure 2 Please provide a detailed explanation.

[0022] Appendix Figure 1 This invention provides a structural block diagram of a thermal balance test system for new energy vehicles, which shows the connection relationship between the humid and cold environment and intake boundary simulation module and the calculation and control host computer module, and marks the main functional interaction flow of each module.

[0023] Appendix Figure 2 The flowchart of a thermal balance test method for new energy vehicles provided in this embodiment of the invention shows the complete steps from reproducing the target temperature and humidity conditions to sending a defrost command to the heat pump under test by a defrost trigger based on a physical threshold.

[0024] In this embodiment, it includes: The humid and cold environment and intake boundary simulation module is configured to include a completely physically isolated external environment simulation chamber and a passenger compartment environment simulation chamber; the simulation chamber is connected to a pure physical saturated steam humidification array, which is sequentially connected to an isothermal electrode steam humidifier, a diffusion chamber and a static mixer, and outputs humid air to the next stage through an anti-condensation heat tracing pipeline; The core function of this module is to stably and accurately reproduce the wet and cold boundary conditions that cause heat pumps to frost or fog, which is the physical basis of the entire latent heat test.

[0025] In the current field of new energy vehicle heat pump testing, existing environmental simulation equipment generally suffers from problems such as poor temperature and humidity uniformity, liquid water droplets being trapped during humidification, and condensation and frost forming on sampling pipelines. This module addresses these issues from three dimensions: environmental chamber structure, humidification method, and pipeline protection.

[0026] Dual-dew-point micro-pressure environment chamber: Existing traditional environmental chambers generally adopt a single-chamber structure or single-duct temperature and humidity control, which can only simulate a single environment. Moreover, they mostly use single-point sampling of return air as control feedback. The temperature and humidity deviation in different areas of the chamber can reach up to 3°C, and the relative humidity deviation can reach up to 15%. At the same time, the pressure control accuracy is insufficient, which can easily lead to problems such as outside air leakage or humid air overflow from the chamber, directly destroying the consistency of the air intake boundary.

[0027] The dual dew point micro-pressure environment chamber used in this test bench is a completely physically isolated dual-chamber structure, corresponding to the external environment simulation chamber and the passenger compartment environment simulation chamber respectively. Except for the two heat exchangers of the heat pump under test, which can be extended into the two chambers respectively, there is no air flow path between the two chambers, which can independently simulate two different temperature, humidity and pressure conditions.

[0028] The entire cabin uses 150mm thick polyurethane foam insulation board as the insulation layer, and both the inner and outer shells are made of 304 stainless steel, with a thermal insulation coefficient of [missing information]. With a humidity level of ≤0.022W / (m·K), condensation on the bulkheads can be avoided, thus preventing the consumption of water vapor inside the cabin and ensuring the accuracy of humidity control.

[0029] Each cavity is equipped with an independent circulating air duct, which integrates an independent refrigeration unit, electric heating unit, humidification unit, and airflow regulation unit, allowing independent control of the temperature and humidity parameters of the corresponding cavity. The external environment simulation cavity has a temperature control range of -40℃ to 60℃, a relative humidity control range of 10% to 98%, and a dew point temperature control range of -45℃ to 50℃, fully covering all frosting conditions of the heat pump in new energy vehicles. The passenger compartment environment simulation cavity has a temperature control range of -10℃ to 85℃ and a relative humidity control range of 5% to 95%, covering the entire operating range of the passenger compartment from cold start to high-temperature exposure.

[0030] The temperature and humidity control adopts a multi-sampling point average feedback logic, abandoning the traditional single-point return air sampling: each cavity's supply air section, middle section, and return air section are equipped with 3 sets of sampling units. Each sampling unit includes one Class A PT100 platinum resistance thermometer (accuracy ±0.05°) and one Vaisala HMT330 series capacitive humidity sensor (accuracy ±1%RH). The control system takes the average measurement value of 6 sets of sampling units as the feedback value. Combined with PID adjustment logic (proportional coefficient P=2.2, integral coefficient I=0.08, derivative coefficient D=0.03), the temperature and humidity uniformity at any location in the cabin can be controlled within ±0.1℃ and ±1%RH. For the core working condition of easy frosting from -20℃ to 5℃, the temperature and humidity control accuracy can be further improved to ±0.08° and ±0.8%RH.

[0031] The micro-pressure control module uses an independent micro-differential pressure transmitter with a range of -50Pa to +50Pa and an accuracy of ±0.1Pa. The control target is to ensure that the internal pressure of the cavity is always 5Pa ±0.5Pa higher than the external atmospheric pressure. This can prevent unconditioned air from leaking into the cavity and prevent a large amount of humid air from overflowing from the chamber due to excessive positive pressure, thus ensuring the stability of humidity control.

[0032] The air outlet of the chamber is equipped with a 100mm long, 6mm aperture honeycomb rectifier grid with an opening rate of 70%. This can control the non-uniformity of the airflow to within 5%, ensuring uniform air velocity on the surface of the heat pump heat exchanger and preventing uneven frost formation caused by excessively high or low local air velocities. The chamber's sealing door uses double silicone rubber sealing strips with integrated heating wires inside. The temperature is controlled at 2°C above the dew point temperature of the air inside the chamber, preventing condensation and icing at the sealing strip and ensuring a good seal.

[0033] Pure physical saturated steam humidification array: Existing humidification solutions generally suffer from two core flaws: Firstly, ultrasonic humidification produces 1-5μm liquid water droplets that are not gaseous water vapor. These droplets directly adhere to the fin surface after entering the heat exchanger and are misjudged as frost, resulting in latent heat measurements being up to 40% higher than expected. Secondly, the steam humidifier lacks a mixing and rectification structure, resulting in uneven mixing of the high-temperature steam jet with dry air. This leads to oversaturation in some areas, causing condensation and also resulting in humidity measurement errors.

[0034] This module uses an isothermal electrode steam humidifier as the core of humidification. Its working principle is that by inserting electrodes into deionized water with a resistivity ≥18.2MΩ·cm, the current passes through the water to generate Joule heat, which heats the water to boiling and produces saturated water vapor at 100℃. The water vapor produced in this way is 100% gaseous, without any liquid water droplets entrained, and the humidity stability of the saturated steam is extremely strong.

[0035] The humidifier's water flow rate is automatically adjusted by a high-precision solenoid valve, with an adjustment range of 0.1g / s to 10g / s, which can cover all humidification needs from low temperature and low humidity to high temperature and high humidity.

[0036] The humidified steam is not directly sent into the air duct, but passes through a two-stage mixing and rectification structure to ensure the uniformity of the humidified air: The first stage is a 304 stainless steel diffuser chamber with a diameter of 300mm and a length of 500mm. Steam is uniformly injected from 12 small holes with a diameter of 2mm at the bottom of the diffuser chamber, and initially mixed with the pre-conditioned dry air entering from the side. The inner wall of the diffuser chamber is coated with polytetrafluoroethylene to prevent steam from condensing on the wall surface. The outlet of the diffuser chamber is equipped with a first-stage orifice plate rectifier with a hole diameter of 5mm and an opening rate of 60%, allowing the initially mixed humidified air to flow evenly. The second stage is a static mixer, which consists of 10 sets of cross-arranged stainless steel corrugated plates with an angle of 45° between adjacent corrugated plates. When the humidified air passes through the corrugated plates, it is repeatedly cut and rotated to ensure that the steam and dry air are completely mixed without local oversaturation areas. The outlet of the static mixer is equipped with a second-stage orifice plate rectifier with a hole diameter of 3mm and an opening rate of 50%, further uniformizing the flow field.

[0037] The rectifier outlet is equipped with a GEM series cold mirror dew point meter (accuracy ±0.1℃ dew point) to measure the dew point temperature of the humidified air in real time and feed it back to the humidifier control unit, ensuring that the dew point temperature of the humidified air deviates from the set value by ≤±0.1℃. Both the diffuser chamber and the static mixer are equipped with drain ports with solenoid valves at their bottoms, automatically draining for 10 seconds every 30 minutes to remove any trace amounts of condensate and prevent it from being carried into the environmental chamber by the airflow. All pipes and outer walls of the entire humidification array are wrapped with 20W / m silicone rubber heating tape, with the heating temperature controlled 3℃ higher than the maximum set dew point temperature. This ensures that the wall temperature throughout the humidification path remains above the air dew point temperature, preventing condensation and ensuring that the humidified air entering the environmental chamber is pure gaseous humidified air without any liquid droplets entrained.

[0038] Anti-condensation heat tracing pipeline The sampling pipelines of existing test benches mostly use ordinary plastic or copper pipes, without heat tracing or with insufficient heat tracing control accuracy. When the temperature of the humid air inside the pipeline is lower than the dew point temperature, condensation will form on the inner wall of the pipeline, resulting in a reduction in the water vapor content in the air and an underestimation of humidity. The latent heat measurement error can reach up to 20%. Under frosting conditions with a dew point below 0°C, the inner wall of the pipeline may also be blocked by frost, causing the measurement to fail completely.

[0039] All piping involved in the humidified air transport on this test bench, including the supply air piping from the environmental chamber to the heat pump inlet, the sampling piping from the heat pump outlet to the sensor, and the connecting piping from the humidification array to the environmental chamber, is made of 304 stainless steel with polished inner walls and a roughness Ra≤0.8μm to prevent moisture from adhering to the pipe walls. A 20W / m silicone rubber electric heating tape is wrapped around the outer wall of the piping. Hard-coded PID control is employed, with parameters tuned using thermal inertia: proportional coefficient P=2.5, integral coefficient I=0.1, and derivative coefficient D=0.05. The control objective is to ensure that the pipe wall temperature is always 2℃±0.2℃ higher than the dew point temperature of the air inside the pipe.

[0040] At least two Class A PT100 platinum resistance thermometers (accuracy ±0.05℃) are attached to the outer wall of each pipeline section to measure the pipe wall temperature. A cold mirror dew point meter is also installed at the pipeline inlet to measure the dew point temperature of the air inside the pipe in real time, serving as feedback for PID control. The pipeline is externally covered with a 50mm thick nano-aerogel insulation layer with an insulation coefficient λ≤0.018W / (m⋅K), reducing heat loss and improving heat tracing stability. All pipeline connections use VCR metal-faced sealed joints to prevent air leakage. Small heat tracing fins are additionally installed at the joints to ensure that the joint wall temperature is also higher than the dew point temperature, preventing condensation and frost formation at the joints.

[0041] All pipelines are tilted at a 1° angle towards the environmental chamber or condensate collection port. Even if a very small amount of condensate is generated, it will flow along the tilted pipeline to the collection port and will not flow into the sensor or heat pump heat exchanger, affecting the measurement results. A photoelectric droplet sensor is installed at the outlet of each sampling pipeline. Once liquid water is detected flowing out, the system automatically issues an alarm and raises the heating temperature by 5°C until the droplet disappears, ensuring that the air entering the sensor is free of liquid water entrainment.

[0042] The air-side enthalpy difference miniature measurement wind tunnel module is configured to be connected to the anti-condensation heat tracing pipeline. The main body of the module is a miniature wind tunnel, and the miniature wind tunnel is equipped with the following components in sequence along the airflow direction: cross-sectional temperature and humidity sampling grid at the air inlet, heat exchanger under test, cross-sectional temperature and humidity sampling grid at the air outlet, anti-disturbance Pitot tube flow meter array, and air state isolator. This module addresses the pain points of existing large-scale enthalpy difference laboratories being unable to adapt to automotive pipeline-level heat exchanger measurements, the low measurement accuracy of traditional automotive test benches, and their susceptibility to failure under frosting conditions. It miniaturizes large-scale enthalpy difference laboratories at the building complex level to the automotive pipeline level, accurately capturing changes in the physical state of the air.

[0043] The main component of this module is a miniature wind tunnel with an adjustable cross-section. The cross-sectional size of the wind tunnel can be adjusted according to the size of the heat exchanger to be tested, with an adjustment range from 100mm×100mm to 500mm×500mm, fully covering the size of all current new energy vehicle external and internal heat exchangers.

[0044] The wind tunnel is constructed entirely of 10mm thick extruded polystyrene board covered with 304 stainless steel sheet, and further encased in a 50mm thick insulation layer, with a heat leakage rate ≤1W / ( (⋅K), to reduce the impact of ambient heat on the measurement.

[0045] Cross-sectional temperature and humidity sampling grid: Existing test benches generally use single-point or a few-point temperature and humidity sampling, which cannot cover the temperature and humidity distribution of the entire cross section. In contrast, heat pump heat exchangers have extremely uneven temperature and humidity distribution at the outlet due to uneven fin efficiency and uneven refrigerant distribution. The maximum temperature difference can reach more than 5°C and the humidity difference can reach more than 15°C. The error of single-point measurement is extremely high, which directly leads to the distortion of enthalpy difference calculation.

[0046] This module configures independent temperature and humidity sampling grids at the inlet and outlet sections of the heat pump heat exchanger, with a grid density following a 50-grid pattern. The principle of setting up one sampling point is to configure 6×6 sampling points in a 300mm×300mm cross section, with each sampling point corresponding to one sampling unit of "PT100 high-precision platinum resistance and high-frequency cold mirror dew point meter".

[0047] The PT100 uses a Class A thin-film platinum resistance thermometer with a response time ≤0.1s and an accuracy of ±0.03℃. During installation, the temperature sensor is directly inserted into the wind tunnel channel to a depth of half the height of the wind tunnel cross-section, ensuring that the air temperature at the center of the channel is measured, not the wall temperature. The high-frequency cold mirror dew point meter uses the British Michel S8000 series, with a response time ≤0.2s, a dew point measurement range of -100℃ to +20℃, and an accuracy of ±0.05℃. The sampling tube of each dew point meter is inserted into the exact same position as the PT100, and a constant flow sampling pump is used to control the sampling flow rate at 1L / min ±0.05L / min to ensure sampling stability.

[0048] All sampling units are fixed on a movable mounting frame with a movement accuracy of ±1mm. The distance between the sampling section and the heat exchanger can be adjusted according to the position of the heat exchanger under test: the distance between the sampling section at the air inlet and the windward side of the heat exchanger is 1.5 times the equivalent diameter of the wind tunnel section, and the distance between the sampling section at the air outlet and the air outlet side of the heat exchanger is 2 times the equivalent diameter of the wind tunnel section. This distance has been verified by simulation and experiment, which can avoid the interference of the heat exchanger on the sampling and ensure that the sampled air is in the true state after passing through the heat exchanger.

[0049] Measurement data from each sampling point is uploaded to the host computer in real time. The average dry-bulb temperature and average dew point temperature of the entire cross-section are calculated using an arithmetic mean method without any weighting coefficients to avoid human error caused by weighting logic. Verified in a standard wind tunnel, the average temperature error of this high-density grid sampling is ≤0.05℃, and the average dew point temperature error is ≤0.08℃, far superior to the accuracy of traditional single-point sampling. All sampling units' sampling tubes are equipped with the same heat tracing structure as described above, with the wall temperature 2℃ higher than the dew point temperature to prevent condensation inside the sampling tubes.

[0050] Disturbance-resistant Pitot tube flow meter array: Current wind speed measurements generally use hot-wire anemometers. Although they have a fast response speed, they are easily affected by dust, water vapor, and ice. In frosting conditions, the surface of the hot wire will be covered with ice, which will cause the measurement accuracy to drop sharply or even fail completely. In addition, hot-wire anemometers have short calibration cycles, high maintenance costs, and poor long-term stability.

[0051] This module uses an S-shaped averaging pitot tube array based on pure fluid dynamics principles for flow measurement. The pressure taps of the S-shaped pitot tubes face and oppose the airflow respectively, making them less prone to clogging by dust and ice. Furthermore, it measures the average dynamic pressure across the entire measurement section, resulting in extremely high stability. The pitot tubes are arranged at a density following a ratio of 100... The principle of setting up one is to use 9 Pitot tubes in a 3×3 configuration for a 300mm×300mm cross section. The length of each Pitot tube is equal to the width of the wind tunnel cross section. It is inserted into the wind tunnel across the entire cross section. Every 30mm on the Pitot tube, there is one dynamic pressure tap and one static pressure tap. The diameter of the tap is 1mm to ensure that the dynamic pressure and static pressure at different locations on the entire cross section can be measured.

[0052] Each pitot tube has its dynamic pressure outlet and static pressure outlet connected to a differential pressure transmitter with a range of 0~100Pa, used to measure the dynamic pressure value of each pitot tube. The host computer first calculates the average dynamic pressure of all pressure taps of a single pitot tube, and then calculates the total average dynamic pressure of all pitot tubes. Then, the average air velocity is calculated based on the dynamic pressure equation: ; in The wet air density is calculated in real time, not the dry air density. The formula for calculating wet air density is: ; In the formula, For dry air partial pressure, The gas constant for dry air is 287 J / (kg⋅K). For water vapor partial pressure, The gas constant for water vapor is 461 J / (kg⋅K). This refers to the absolute temperature of the air.

[0053] The air volumetric flow rate is calculated by multiplying the average flow velocity by the wind tunnel cross-sectional area, and the mass flow rate is calculated by multiplying the volumetric flow rate by the humid air density. The wind tunnel cross-sectional area is calibrated using laser ranging with a calibration accuracy of ±0.1 mm and a cross-sectional area error of ≤0.05. The pitot tube is installed downstream of the temperature and humidity sampling grid at the air outlet, at a distance equal to one equivalent diameter of the wind tunnel cross-section, to avoid interference from the pitot tube in the temperature and humidity sampling.

[0054] The pressure tapping lines of the Pitot tubes are all made of 304 stainless steel pipes with a diameter of 6mm. The lines are equipped with a heat tracing structure, and the temperature is controlled at 50℃ to prevent condensation and frost from clogging the pressure tapping holes. Each pressure tapping line is also equipped with an automatic purging function, which purges the pressure tapping holes with 0.2MPa dry nitrogen for 10 seconds every 1 hour to ensure that the pressure tapping holes are unobstructed.

[0055] Air condition isolator: The air at the heat exchanger outlet has uneven heating and cooling, as well as uneven humidity. Especially under some frosting conditions, the frosted area has low wind speed, high temperature, and low humidity, while the non-frosted area has high wind speed, low temperature, and high humidity. Even with grid sampling, measurement errors can still occur due to airflow pulsation and local unevenness.

[0056] The air state isolator is located downstream of the Pitot tube array at the air outlet and is an adiabatic mixing chamber. The length of the mixing chamber is three times the equivalent diameter of the wind tunnel section, and the cross-sectional area is 2.5 times the cross-sectional area of ​​the wind tunnel. After the airflow enters the mixing chamber, the flow velocity is reduced to 1 / 2.5 of the original flow velocity, thus improving the stability of the flow field.

[0057] The inner wall of the mixing chamber is coated with polytetrafluoroethylene to prevent moisture adhesion. Three sets of static mixing baffles are installed inside, each set consisting of cross-arranged stainless steel plates at a 45° angle. The orientation of adjacent sets of baffles differs by 90°. As the airflow passes through the baffles, it is repeatedly cut, rotated, and mixed, ensuring complete and uniform mixing of hot and cold air, as well as dry and humid air. A 100-mesh stainless steel rectifier screen is installed at the mixing chamber outlet to further homogenize the flow field and reduce airflow pulsation.

[0058] The mixing chamber is externally covered with a 50mm thick nano-aerogel insulation layer, with a heat leakage rate ≤0.5W / ( •K), to ensure no heat loss during mixing and no change in air enthalpy.

[0059] The refrigerant-side heat balance cross-verification module is configured to include a Coriolis mass flow meter connected in series in the pipeline and an immersion thermodynamic probe installed in the pipeline, which is used to obtain the refrigerant state and calculate the refrigerant-side heat exchange, so as to form an energy verification with the heat exchange measured on the air side. This module performs energy verification by measuring the physical parameters on the refrigerant side and comparing them with the measurement results on the air side.

[0060] The core logic of this module is: the deviation between the heat exchange on the refrigerant side and the heat exchange on the air side should be controlled within ±2. If it exceeds this range, the system will automatically alarm and troubleshoot the fault to ensure the measurement accuracy of the entire test system.

[0061] Coriolis mass flow meter: Current refrigerant flow measurement generally uses vortex flow meters or volumetric flow meters, which have low measurement accuracy, especially under two-phase flow conditions of refrigerant, where the measurement error can reach more than 10%. Furthermore, they cannot measure transient flow and suffer from severe measurement distortion under transient conditions such as defrosting.

[0062] This module uses the Gaozhun ELITE series Coriolis mass flow meter, with an accuracy of ±0.1 reading and repeatability of ±0.05. It can measure the flow rate of single-phase and two-phase refrigerants, unaffected by refrigerant density, viscosity, temperature, and pressure, and is fully compatible with the refrigerant flow measurement requirements of heat pump systems. The flow meters are connected in series in the high-pressure and low-pressure lines of the heat pump: the flow meter in the high-pressure line is installed between the compressor outlet and the condenser inlet, and the flow meter in the low-pressure line is installed between the evaporator outlet and the compressor inlet. It can simultaneously measure the refrigerant mass flow rate on both the high-pressure and low-pressure sides. Under normal operating conditions, the deviation between the two should be ≤±0.2. If it exceeds this range, it indicates that there is a refrigerant leak in the system, and an automatic alarm will be triggered.

[0063] The flow meter installation strictly adheres to the requirements for upstream and downstream straight pipe sections: the upstream straight pipe section is 10 times the pipe diameter, and the downstream straight pipe section is 5 times the pipe diameter, ensuring a stable refrigerant flow field without swirling flow and improving measurement accuracy. The flow meter body is equipped with a heat tracing and insulation structure, with the heat tracing temperature controlled 5°C above the refrigerant condensation temperature to prevent the refrigerant from condensing inside the flow meter and generating two-phase flow, which would affect measurement accuracy. The flow meter undergoes specialized calibration by the original manufacturer for the refrigerant being measured (such as R134a and R1234yf), with a calibration flow range from 0.1 kg / h to 100 kg / h, covering the refrigerant flow range of all automotive heat pumps. Furthermore, it can be traced back to the national metrology institute's standard device for annual calibration, ensuring measurement traceability.

[0064] Immersion thermodynamic probe: Current methods for measuring refrigerant temperature and pressure generally use externally mounted sensors or ordinary thermocouples inserted into the pipes. However, the insertion depth is insufficient, and the measured temperature is the pipe wall temperature rather than the actual temperature of the refrigerant. Pressure measurements often use pressure taps to lead to external transmitters, but the refrigerant inside the pressure taps may condense, resulting in large pressure measurement errors. Furthermore, the slow response speed under transient conditions makes it impossible to capture rapid changes in the refrigerant's state.

[0065] This module uses an integrated armored thermocouple and pressure transmitter combined immersion probe. The probe diameter is 3mm, made of 316L stainless steel, and can withstand a maximum pressure of 20MPa. It is compatible with... High-pressure measurement requirements for transcritical heat pumps. The thermocouple's sensing head is located at the very tip of the probe, using a T-type armored thermocouple with an accuracy of ±0.1℃ and a response time ≤0.05s. The probe is inserted into the center of the pipe, directly contacting the refrigerant, measuring the true temperature of the refrigerant rather than the pipe wall temperature. The pressure transmitter's pressure tap is located on the side of the probe, 5mm from the sensing head, directly contacting the refrigerant without the need for a pressure tapping tube, completely eliminating errors introduced by the tube. The pressure transmitter has an accuracy of ±0.05℃ and a response time ≤0.05s. The range is selected according to the refrigerant type: 0-4MPa for R134a and R1234yf, and for... Select the 0~15MPa range.

[0066] The probes are installed at six locations: compressor inlet and outlet, expansion valve inlet and outlet, condenser inlet and outlet, and evaporator inlet and outlet. They can measure the temperature and pressure of the refrigerant at each component's inlet and outlet in real time, and calculate the heat exchange of each component. The probes are fixed to the pipeline by welding, and metal gaskets are used for sealing to ensure no refrigerant leakage. The probe leads are shielded to avoid electromagnetic interference and ensure stable measurement signals. Each probe has been calibrated by the National Institute of Metrology, with a temperature calibration range of -40℃ to 150℃ and a pressure calibration range of 0 to 20MPa. The calibration accuracy is traceable, ensuring measurement accuracy.

[0067] Thermal equilibrium cross-validation logic: The heat exchange calculation on the refrigerant side is entirely based on the standard refrigerant property data from the NISTREFPROP database. All property data is hard-coded into the host computer, eliminating the need for online lookup and ensuring stable calculations. First, the corresponding refrigerant specific enthalpy is retrieved based on the refrigerant temperature and pressure at each location. Then, the heat exchange on the high-pressure side and the low-pressure side was calculated separately: High-pressure side heat exchange: ; In the formula, This refers to the mass flow rate of the refrigerant on the high-pressure side. For the specific enthalpy of the refrigerant at the compressor outlet, This refers to the specific enthalpy of the refrigerant at the condenser outlet.

[0068] Low-pressure side heat exchange: ; In the formula, This refers to the refrigerant mass flow rate on the low-pressure side. The specific enthalpy of the refrigerant at the evaporator outlet. The specific enthalpy of the refrigerant at the expansion valve outlet.

[0069] Heat exchange on the air side The total heat exchange calculated by the enthalpy difference method : Its specific calculation logic is based on the product of the air-side mass flow rate and the specific enthalpy difference between the inlet and outlet air vents, as shown in the formula: ,in, The air-side mass flow rate is measured and calculated by the disturbance-resistant Pitot tube flowmeter array of the air-side enthalpy difference miniaturized measurement wind tunnel module; , These are the average specific enthalpy of the air inlet and outlet of the heat pump heat exchanger, respectively. They are calculated by the air specific enthalpy hard-coded solver in the calculation and control host computer module based on the dry bulb temperature and dew point temperature measured by the cross-sectional temperature and humidity sampling grid. Under refrigeration conditions, Should be with The deviation is ≤ ±2; under heating conditions, Should be with The deviation is ≤ ±2.

[0070] If the deviation exceeds this range, the system will automatically check the working status of the temperature and humidity sensor, flow sensor, and pressure sensor in sequence. After troubleshooting, the test will be repeated to completely eliminate the system error of unilateral measurement. The heat exchange measurement error of the entire system can be controlled within ±1, which is far higher than the accuracy level of existing test benches.

[0071] The defrosting phase change physical measurement and calibration module is configured to be located directly below the heat exchanger under test. It includes a flow-guiding constant temperature water receiving tray and a closed-loop micro-weighing system placed inside the windproof cover. It is used to measure the mass of liquid water generated during defrosting, which serves as the calibration benchmark for latent heat measurement. In existing technologies, latent heat measurement can only be indirectly calculated through enthalpy difference, lacking direct physical calibration methods. This makes the accuracy of the measurement results easily questionable, especially regarding the latent heat loss during the frosting and defrosting process, which cannot be directly quantified by current technologies, resulting in errors exceeding 20%. This module directly measures the mass of liquid water produced during defrosting, directly deducing the absolute value of the latent heat of phase change, which serves as the calibration benchmark for enthalpy difference method latent heat measurement.

[0072] Flow-guiding thermostatic water receiving tray: Existing water receiving trays generally lack a flow guiding structure, making it easy for defrost water to remain in the corners of the tray or splash out, resulting in a lower measured water mass. Furthermore, the water receiving trays lack a constant temperature heating function, causing defrost water to freeze again on the tray and fail to flow into the weighing device, leading to measurement errors or even failure.

[0073] The thermostatic water collection tray used in this module is 50mm larger than the windward side of the heat exchanger under test, ensuring that all defrosting water falls onto the tray. The tray is made of 304 stainless steel with a polished inner wall and a roughness Ra≤0.8μm to prevent moisture adhesion. The bottom of the tray is inclined at 1°, and a 10mm wide and 5mm deep guide channel is set at the lowest point. All defrosting water flows along the inclined bottom to the guide channel, and then flows into the weighing system below through the outlet of the guide channel.

[0074] The drip tray is internally fitted with a 50W / m² constant-temperature heating wire, employing PID control to maintain the inner wall temperature of the drip tray at 5℃±0.2℃. This temperature prevents the defrost water from refreezing while also preventing excessive evaporation, thus avoiding measurement errors. Two Class A PT100 platinum resistance thermometers are attached to the inner wall of the drip tray to measure its temperature, serving as feedback values ​​for the PID control. A 20mm high baffle is installed around the edge of the drip tray to prevent defrost water from splashing out, and the top of the baffle has an inward-curving edge to prevent water dripping from the heat exchanger from splashing onto the outside of the drip tray. The drip tray is externally covered with a 20mm thick insulation layer to reduce heat loss and improve temperature control stability.

[0075] The drip tray is installed directly below the external heat exchanger, 100mm from the bottom of the heat exchanger. This design ensures that it does not obstruct the airflow into the heat exchanger while guaranteeing that all dripping defrost water falls onto the drip tray. The outlet of the deflector is equipped with a PTFE (polytetrafluoroethylene) deflector pipe with a diameter of 8mm and a smooth inner wall. Defrost water flows through the deflector pipe into the weighing container below. The outlet of the deflector pipe is 10mm from the bottom of the weighing container to prevent water droplets from splashing out.

[0076] Micro-weighing system: Existing weighing devices generally lack windproof structures, and airflow disturbances can cause weighing errors of up to several grams. In particular, under the influence of wind tunnel airflow, the weighing fluctuations are extremely large, which cannot meet the requirements of high-precision measurement. Furthermore, there is no temperature compensation function, and the zero-point drift of the weighing sensor caused by temperature changes will also affect the measurement accuracy.

[0077] This module uses a Mettler Toledo ME series high-precision electronic balance with a range of 0-6000g, an accuracy of 0.1g, and a repeatability of ±0.05g, fully meeting the measurement requirements for defrosting water. The balance is installed inside a sealed windproof cover made of 10mm thick transparent acrylic, with an internal volume of 300mm×300mm×300mm. An opening for inserting a guide tube is provided at the top of the windproof cover, and the opening is sealed with silicone rubber to prevent airflow from entering the windproof cover and affecting the weighing.

[0078] The windproof shield is equipped with temperature and pressure sensors to measure the internal temperature and pressure in real time, and to perform buoyancy compensation: air buoyancy affects the weight distribution, and the magnitude of buoyancy is equal to the mass of displaced air. Therefore, the actual water mass is calculated using the following formula: ; In the formula, The air density inside the windshield. The total volume of the weighing container and the water inside. The apparent mass of defrost water was directly measured by a high-precision electronic balance (the original reading without buoyancy compensation). This compensation logic completely eliminates errors caused by buoyancy, improving weighing accuracy. The weighing container is an open-top polyethylene container with a volume of 5L. Its smooth inner wall prevents moisture adhesion, and the exterior is coated with a black light-blocking coating to prevent direct sunlight from causing moisture evaporation.

[0079] The weighing system is equipped with an automatic calibration function, automatically calibrating with a built-in 1000g standard weight before each daily test, with a calibration accuracy of ≤0.05g to ensure weighing accuracy. The entire weighing system is installed on an independent vibration-damping platform with a natural frequency of ≤1Hz to avoid the influence of ground vibration on weighing. Testing showed that under wind tunnel conditions of 10m / s, the weighing fluctuation was ≤0.05g, fully meeting the measurement requirements.

[0080] Phase change latent heat calibration logic: During defrosting, the latent heat of phase change for solid ice crystals melting into liquid water is 334 J / g (the latent heat of ice transforming into water at 0℃). If the temperature of the melted water rises to 5℃, it also needs to absorb 4.2 J / (g⋅℃) of sensible heat. Therefore, the formula for calculating the absolute value of the latent heat consumed in the entire defrosting process is: ; In the formula, The water temperature inside the weighing container is measured in real time using a PT100; 334 is the latent heat constant of phase change per unit mass when solid ice at 0℃ melts into liquid water at 0℃; 4.2 is the specific heat capacity constant per unit mass at constant pressure of liquid water; 0 is the critical thermodynamic reference temperature at which ice and liquid water undergo a solid-liquid phase change under standard atmospheric pressure. Should It is based entirely on absolute values ​​obtained from physical measurements, and is compared with the latent heat transfer calculated using the enthalpy difference method. If the deviation between the two exceeds the preset allowable range, it indicates that there is a systematic error in the temperature, humidity or flow rate measurement on the air side. The system will automatically calibrate the air side sensor to ensure the accuracy of latent heat separation.

[0081] The calculation and control host computer module is configured to communicate with the above modules. It has an embedded air specific enthalpy hard-coded solver, latent heat / sensible heat separation operator, and a defrosting trigger based on physical threshold. The host computer module separates the latent heat transfer based on the cross-sectional temperature and humidity sampling grid and the measurement values ​​of the anti-disturbance Pitot tube flow meter array, and triggers the defrosting action through the defrosting trigger based on physical threshold when the inlet and outlet pressure difference and the proportion of latent heat transfer meet the preset physical threshold conditions. Air enthalpy hard-coded solver: First, based on the measured dry-bulb temperature and dew point temperature The saturated partial pressure of water vapor was calculated using the Wexler-Hyland saturated vapor pressure equation. .

[0082] Water vapor partial pressure equal to dew point temperature Corresponding saturated vapor pressure Since the dew point temperature is the temperature at which water vapor reaches saturation, therefore: ; Then calculate the absolute humidity (moisture content): ; In the formula, The total air pressure is measured in real time by a pressure sensor.

[0083] The formula for calculating the specific enthalpy of moist air is: ; In the formula, The specific heat of dry air at constant pressure is 1005 J / (kg⋅K). The specific heat of water vapor at constant pressure is 1860 J / (kg⋅K). The latent heat of vaporization of water vapor at 0℃ is 250-1000 J / kg. All constants are based on ASHRAE standard values ​​without any correction factors.

[0084] The solver has built-in data validity verification logic. The temperature and humidity data of each sampling point will be verified. For example, the dew point temperature cannot be higher than the dry bulb temperature. If unreasonable data is found, the system will automatically remove it and replace it with interpolated data from adjacent sampling points to avoid abnormal data affecting the solution results.

[0085] Latent heat / sensible heat separation operator: This operator is also hard-coded into the FPGA chip, and all formulas are direct applications of the first law of thermodynamics, without any empirical parameters. The formula for calculating the total heat exchange is: ; In the formula, The air-side mass flow rate is measured using a Pitot tube array. , This is the average specific enthalpy of the air inlet and outlet.

[0086] The formula for calculating sensible heat transfer is: ; In the formula, The formula for calculating the specific heat at constant pressure of moist air is: ; Based on real-time measured moisture content The sensible heat calculation is obtained by calculation, rather than by using the specific heat of dry air at constant pressure, which further improves the accuracy of sensible heat calculation.

[0087] The formula for calculating latent heat transfer is: ; Latent heat is the heat released or absorbed by water vapor in the air during a phase change (frost or condensation). Without any fitting step, the calculation results are completely deterministic and reproducible. The operator calculates the proportion of latent heat transfer to total heat transfer in real time. This ratio directly reflects the frosting condition of the heat exchanger: the greater the amount of frost, the more severe the frost layer covers the fin surface, the less water vapor can condense on the cold surface, and the lower the latent heat ratio.

[0088] Defrost trigger based on physical threshold: Existing defrosting triggers either use timed control, forcing defrosting even when the amount of frost is small, resulting in energy waste; or they use AI to predict frost, but the black-box model is unreliable and has a high false alarm rate; or they use a single differential pressure threshold, but an increase in differential pressure may be caused by filter blockage rather than frost, resulting in a high false alarm rate.

[0089] This trigger is hard-coded into the FPGA chip and uses AND logic with two physical thresholds. Defrosting is only triggered when both conditions are met simultaneously, thus avoiding false alarms.

[0090] The first threshold is the pressure difference between the air inlet and outlet. A jump exceeding 30% of the initial value: The initial value is the inlet and outlet pressure difference when the heat pump just starts running and before frost forms. The pressure difference is obtained by static pressure measurement through the Pitot tube array. When the pressure difference exceeds 30% of the reference value, it indicates that there is frost accumulation between the heat exchanger fins and the air resistance increases.

[0091] The second threshold is a sharp drop of more than 20% in the proportion of latent heat transfer: compared with the stable latent heat proportion before frosting, a drop of more than 20% in the proportion of latent heat indicates that the frost layer has covered most of the fin surface, water vapor cannot condense, and the latent heat transfer has dropped significantly.

[0092] The system determines that frost is obstructing heat exchange only when both conditions are met simultaneously. It then automatically sends a CAN message to the controller of the heat pump under test, instructing it to perform defrosting. An additional forced defrosting logic is configured on the trigger. If the heat pump runs continuously for 2 hours without triggering defrosting, the system will force defrosting to prevent excessive frost buildup from damaging the heat exchanger.

[0093] Example 2 Please see Figure 2 A method for thermal balance testing of new energy vehicles, comprising the following parts: The target temperature and humidity conditions are reproduced by the humid and cold environment and air intake boundary simulation module. Pure gaseous humid air without liquid droplets is output to the heat pump under test through the pure physical saturated steam humidification array and anti-condensation heat tracing pipeline. The air-side enthalpy difference miniaturized measurement wind tunnel module is used to obtain the air physical state and flow velocity before and after heat exchange in real time; the calculation and control host computer module calls the air specific enthalpy hard-coded solver and the latent heat / sensible heat separation operator to separate the total heat exchange and latent heat exchange on the air side. Run the refrigerant-side heat balance cross-verification module to obtain the physical state of the refrigerant and calculate the heat exchange on the refrigerant side; compare the heat exchange on the refrigerant side with the total heat exchange on the air side, and if the deviation exceeds the preset physical verification threshold range, trigger an abnormal alarm to eliminate the single-sided measurement error; When the pressure difference between the inlet and outlet of the heat exchanger increases and the proportion of latent heat transfer decreases, meeting the preset physical threshold conditions, a defrosting trigger based on the physical threshold sends a defrosting command to the heat pump under test. During defrosting, the defrosting phase change physical metering and calibration module is used to weigh the defrosting water and obtain the absolute value of the latent heat of phase change. This absolute value is then used to physically calibrate the latent heat transfer.

[0094] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

[0095] It should be noted that, in this document, the use of relational terms such as "first" and "second" is merely for distinguishing one entity or operation from another, and does not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0096] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0097] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0098] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0099] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0100] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0101] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0102] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A thermal balance testing system for new energy vehicles, characterized in that, include: The humid and cold environment and intake boundary simulation module is configured to include an external environment simulation chamber and a passenger compartment environment simulation chamber; the simulation chamber is connected to a saturated steam humidification array and outputs humid air; The air-side enthalpy difference miniature measurement wind tunnel module is configured to be connected to the anti-condensation heat tracing pipeline. The main body of the module is a miniature wind tunnel, and the miniature wind tunnel is equipped with the following components in sequence along the airflow direction: cross-sectional temperature and humidity sampling grid at the air inlet, heat exchanger under test, cross-sectional temperature and humidity sampling grid at the air outlet, anti-disturbance Pitot tube flow meter array, and air state isolator. The refrigerant-side heat balance cross-verification module is configured to acquire the refrigerant status and calculate the refrigerant-side heat exchange, so as to form an energy verification with the heat exchange measured on the air side. The defrosting phase change physics measurement and calibration module is configured to be installed below the heat exchanger under test to measure the mass of liquid water produced during defrosting, which serves as the calibration benchmark for latent heat measurement. The host computer module for calculation and control is configured to calculate the latent heat exchange and trigger the defrosting action through a defrosting trigger when the inlet and outlet pressure difference and the proportion of latent heat exchange meet the preset physical threshold conditions.

2. The thermal balance testing system for new energy vehicles according to claim 1, characterized in that, The wet and cold environment and intake boundary simulation module includes a dual dew point micro-pressure environment chamber, which is a completely physically isolated external environment simulation chamber and passenger compartment environment simulation chamber; Multiple sampling units are arranged in different sections of the simulation cavity, and the system takes the average value of the measurements from multiple sampling units as the feedback value for temperature and humidity control. The simulation chamber is also equipped with a micro-pressure control module, whose control objective is to maintain the internal pressure of the chamber above the external atmospheric pressure by a preset positive pressure threshold.

3. The thermal balance testing system for new energy vehicles according to claim 2, characterized in that, The humid and cold environment and air intake boundary simulation module also includes a purely physical saturated steam humidification array and an anti-condensation heat tracing pipeline. The pure physical saturated steam humidification array includes an isothermal electrode steam humidifier, whose output steam flows sequentially through a first-stage diffusion chamber with distribution holes and a second-stage static mixer containing cross-arranged corrugated plates. The outer wall of the anti-condensation heat tracing pipeline is equipped with an electric heat tracing cable, and a cold mirror dew point meter is installed at its inlet to measure the dew point temperature of the air inside the pipeline in real time, so as to control the pipeline wall temperature to always be higher than the preset safe temperature difference of the dew point temperature.

4. The thermal balance testing system for new energy vehicles according to claim 1, characterized in that, The main body of the air-side enthalpy difference miniature measurement wind tunnel module is a miniature wind tunnel with an adjustable cross-section, which is equipped with independent inlet cross-section temperature and humidity sampling grids and outlet cross-section temperature and humidity sampling grids. The distance between the sampling grid and the heat exchanger under test is set proportionally to the equivalent diameter of the wind tunnel section. The sampling grid is evenly distributed with sampling units including platinum resistance thermometers and high-frequency cold mirror dew point meters at a preset density. The temperature sensing probe of the sampling unit extends into the center of the wind tunnel channel.

5. The thermal balance testing system for new energy vehicles according to claim 1, characterized in that, The air-side enthalpy difference miniaturized measurement wind tunnel module also includes a disturbance-resistant Pitot tube flowmeter array and an air state isolator; The anti-disturbance Pitot tube flow meter array uses a preset number of S-shaped averaging pitot tubes spanning the cross section of the wind tunnel, with dynamic pressure taps and static pressure taps spaced apart along the axial direction for each Pitot tube. The air state isolator is located downstream of the Pitot tube at the air outlet. It is an adiabatic mixing chamber with an enlarged cross-sectional area and contains cross-arranged static mixing baffles.

6. The thermal balance testing system for new energy vehicles according to claim 1, characterized in that, The refrigerant-side thermal balance cross-validation module includes a Coriolis mass flow meter and an immersion thermodynamic probe; The Coriolis mass flow meter is connected in series in the high-pressure and low-pressure pipelines of the heat pump under test, and is equipped with a heat tracing structure. The immersion thermodynamic probe is a combination probe that integrates an armored thermocouple and a pressure transmitter. Its temperature sensing head and the side pressure tap without a pressure tapping tube extend directly into the refrigerant pipeline to contact the actual fluid.

7. The thermal balance testing system for new energy vehicles according to claim 6, characterized in that, The refrigerant-side thermal balance cross-validation module executes the thermal balance cross-validation logic: The refrigerant specific enthalpy is determined by querying a hard-coded standard refrigerant property database based on real-time refrigerant temperature and pressure measured by probe, and the heat exchange on the high-pressure side and low-pressure side is calculated by combining the mass flow rate. When the calculated refrigerant-side heat exchange rate deviates from the total heat exchange rate calculated on the air side by more than the preset heat balance cross-validation deviation ratio, a system alarm is triggered.

8. The thermal balance testing system for new energy vehicles according to claim 1, characterized in that, The defrosting phase change physical measurement and calibration module includes a flow-guided constant temperature water receiving tray and a micro-weighing system; The bottom of the flow-guiding constant temperature water receiving tray is set with an inclined angle and a flow-guiding groove, and a constant temperature heating wire is embedded inside to keep the water receiving tray in a preset non-freezing and anti-evaporation temperature range. The micro-weighing system includes a high-precision electronic balance housed inside a sealed windproof cover. The windproof cover is equipped with temperature and pressure sensors to obtain air density and to compensate for and correct the weighing results of the balance by air buoyancy.

9. A thermal balance testing system for new energy vehicles according to claim 1, characterized in that, The solver based on pure thermodynamic rules calculates absolute humidity and enthalpy of moist air based on measured dry-bulb temperature and dew point temperature, using hard-coded standard saturated vapor pressure equation and equation of state. The separation operator dynamically calculates the isobaric specific heat of moist air based on real-time absolute humidity to solve for the sensible heat transfer, and obtains the determined latent heat transfer by subtracting the sensible heat transfer from the total heat transfer based on the first law of thermodynamics. It also includes defrost triggers based on physical thresholds: The defrost trigger uses a dual physical threshold AND logic: it monitors in real time the rise rate of the static pressure difference between the inlet and outlet air relative to the initial reference value, as well as the decrease rate of the latent heat transfer rate as a percentage of the total heat transfer rate. Only when the rise rate is greater than the first preset physical threshold and the decrease rate is greater than the second preset physical threshold, a defrost command is sent to the heat pump under test.

10. A method for thermal balance testing of new energy vehicles, comprising a thermal balance testing system for new energy vehicles according to any one of claims 1-9, characterized in that, include: The target temperature and humidity conditions are reproduced by the humid and cold environment and air intake boundary simulation module. Pure gaseous humid air without liquid droplets is output to the heat pump under test through the pure physical saturated steam humidification array and anti-condensation heat tracing pipeline. The air-side enthalpy difference miniaturized measurement wind tunnel module is used to obtain the air physical state and flow velocity before and after heat exchange in real time; the calculation and control host computer module calls the air specific enthalpy hard-coded solver and the latent heat / sensible heat separation operator to separate the total heat exchange and latent heat exchange on the air side. Run the refrigerant-side heat balance cross-verification module to obtain the physical state of the refrigerant and calculate the heat exchange on the refrigerant side; compare the heat exchange on the refrigerant side with the total heat exchange on the air side, and if the deviation exceeds the preset physical verification threshold range, trigger an abnormal alarm to eliminate the single-sided measurement error; When the pressure difference between the inlet and outlet of the heat exchanger increases and the proportion of latent heat transfer decreases, meeting the preset physical threshold conditions, a defrosting trigger based on the physical threshold sends a defrosting command to the heat pump under test. During defrosting, the defrosting phase change physical metering and calibration module is used to weigh the defrosting water and obtain the absolute value of the latent heat of phase change. This absolute value is then used to physically calibrate the latent heat transfer.

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