A refrigerator freshness performance evaluation test device and method

Abstract

The application discloses a refrigerator fresh-keeping performance evaluation test device and method, and belongs to the technical field of refrigerator fresh-keeping performance evaluation test devices. The device comprises a standard test box, a condenser, a compressor, an evaporator and a humidifier. The condenser is connected with the compressor, and the compressor is connected with the evaporator. Cold air is blown into the standard test box through a fan. The humidifier is connected with an air inlet of the standard test box. A temperature and humidity adjusting device is arranged on the standard test box, so that the temperature and humidity of the standard test box can be accurately adjusted. The application solves the problems that the fresh-keeping effect of a refrigerator is difficult to test and evaluate, different fresh-keeping technologies are difficult to be compared horizontally, and a unified comparison test method and standard cannot be formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of household appliances, in particular to a refrigerator fresh-keeping performance evaluation test device and method. BACKGROUND

[0002] According to the data of the State Household Appliances Industry Information Center, the household refrigerator ownership has tended to be saturated, and the refrigerator ownership per hundred households of urban residents reached 98 in 2017, and the refrigerator ownership per hundred households of rural residents reached 92. The refrigerator industry in China has entered the replacement period, and the incremental demand is slowing down. In order to maintain growth and serve the high-quality consumer demand, most refrigerator enterprises focus on the update and iteration of "fresh-keeping" technology in the development of refrigerator technology.

[0003] Modern people's life rhythm is accelerating, and the living standard is improving, and the people's demand for the quality of life is also getting higher and higher. Household appliances are widely used in various fields of human life, so people's choice of refrigerator not only considers price, appearance, and other factors. Whether the refrigerator can really help the healthy life has gradually become a reference index for consumers to purchase products. The "food fresh-keeping function" has almost become a necessary function of household refrigerators. Whether the refrigerator can really fresh-keep vegetables, fruits, fish, and other food materials put into it has become a very concerned problem.

[0004] In the international market, the refrigerator products also show the consumption trend of large capacity and healthy fresh-keeping. Global refrigerator enterprises have increased research and development investment in refrigerator fresh-keeping functions. The current technical means for realizing refrigerator fresh-keeping in the market mainly include low-temperature fresh-keeping, light wave fresh-keeping, adsorption fresh-keeping, water-locking fresh-keeping, quick-freezing fresh-keeping, 0℃ biological fresh-keeping, multi-temperature fresh-keeping, vacuum fresh-keeping, and bacteria-removing fresh-keeping. Which fresh-keeping technology has the best effect, and how to scientifically and accurately evaluate the actual effect of the refrigerator fresh-keeping technology have become the most critical technical problems.

[0005] The existing refrigerator fresh-keeping technology evaluation method is to use two refrigerators of the same batch and the same specification as the "test group" sample and the "control group" sample for performance comparison test. The product with the refrigerator fresh-keeping function turned on is used as the "test group" sample, and the product with the refrigerator fresh-keeping function turned off is used as the "control group" sample. The test is to put similar food materials in the two samples to evaluate. The test purpose is to confirm the effect of the "test group" sample on food preservation compared with the "control group" sample.

[0006] Since the existing method mainly has the following unsolvable technical problems, it is difficult to be practically applied to the detection and evaluation of the "fresh-keeping performance" of the refrigerator.

[0007] 1. Currently, many refrigerator products employ composite or combined "preservation" technologies. This makes it difficult to completely distinguish the "preservation" operation from normal operation, or to independently disable the "preservation" function. If the "preservation" function of the "control group" prototype is to be disabled separately through special methods or settings for "preservation" performance testing, it may cause problems such as abnormal refrigerator operation or shortened operating time, failing to fully achieve the effect of the test control. Even if the "control group" prototype can completely disable the "preservation" function independently without affecting its own operation, individual differences between refrigerators will still exist. 注1 Even so, significant experimental errors can still occur. This is because, even when conducting "refrigeration preservation" performance tests on refrigerators of the same specifications produced by the same company, the individual performance differences of the different machines used in each test will lead to certain variations in the test results. These differences may be negligible to consumers, but for testing, evaluation, analysis, and research, the resulting deviations in test results seriously affect the validity of the final test results.

[0008] Note 1: The refrigerators manufactured by this company are targeted at the general consumer market. Due to cost considerations, the key components (such as compressors, temperature and humidity sensors, etc.) selected by the company and the limitations of the product manufacturing process may lead to certain differences between products. At the same time, even refrigerators with exactly the same specifications may be products produced at different times, with different manufacturing equipment, and in different batches, so there are still certain quality differences between products, which in turn cause certain performance differences.

[0009] 2. Because there is no standardized testing equipment like a "standard test chamber" that provides metric data and has sufficiently stable performance as a "reference performance baseline," refrigerators of the same specifications but different models from different manufacturers cannot be compared horizontally due to their different comparison bases (the "control group" prototypes are produced by each company and have different specifications). In other words, refrigerators produced by company A and refrigerators produced by company B cannot be compared in terms of preservation performance because their operation differs significantly.

[0010] 3. Because the "control group" prototype varies depending on the "experimental group" prototype used in each test, and is not a standard device, it cannot be quantified. Therefore, the test results of the "control group" prototype cannot be used for value transfer. That is, even if the same "experimental group" and "control group" prototypes are used, the test data obtained by Laboratory A and Laboratory B cannot be trusted or compared due to differences in test conditions between laboratories and the fact that the "control group" prototype is not a quantifiable device. The results of each test can only be used for comparison and reference.

[0011] In short, the above-mentioned problem is equivalent to that there is no unified ruler for measuring length, but each family has its own ruler, and these rulers are not stable enough, so the results measured by these rulers cannot be compared with each other. SUMMARY

[0012] To this end, the present application provides a refrigerator fresh-keeping performance evaluation test device and method to solve the problem that the existing refrigerator fresh-keeping effect is difficult to test and evaluate, different fresh-keeping technologies are difficult to compare horizontally, and a unified comparison test method and standard cannot be formed.

[0013] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0014] According to the first aspect of the present application, a refrigerator fresh-keeping performance evaluation test device is disclosed, which comprises a standard test box, a condenser, a compressor, an evaporator and a humidifier, the condenser is connected with the compressor, the compressor is connected with the evaporator, cold air is blown into the standard test box through a fan, the humidifier is connected with the air inlet of the standard test box, and a temperature and humidity adjusting device is arranged on the standard test box to accurately adjust the temperature and humidity of the standard test box.

[0015] Further, the condenser is adjacent to a first fan, which cools the condenser through heat dissipation, and the condenser is connected with the compressor.

[0016] Further, the exhaust port of the compressor is connected with the condenser, and the suction port of the compressor is connected with the evaporator, which is throttled through a throttle valve, adiabatic expansion, and the refrigerant is compressed in the compressor to realize the circulation of the refrigerant between the condenser, the compressor and the evaporator.

[0017] Further, the evaporator is connected with the compressor, the refrigerant absorbs heat and evaporates in the evaporator, the second fan blows cold air into the air inlet of the standard test box, and the third fan blows the gas participating in cooling in the standard test box out of the air outlet of the standard test box.

[0018] Further, the second fan blows the cold air after cooling the evaporator into the standard test box to refrigerate the standard test box, and the third fan sucks out the air with higher temperature from the standard test box.

[0019] Further, the standard test box adopts double-layer vacuum glass and foaming material, the inner layer of the standard test box is provided with a plurality of shelves, the top of the outer layer of the standard test box is provided with an air inlet, and the bottom is provided with an air outlet, and the refrigerant exchanges heat with the air in the box through the evaporator outside the standard test box.

[0020] Further, the standard test box is provided with a temperature adjusting device, which can accurately control the refrigeration performance of the compressor system, so that the actual temperature in the box body is not more than 0.5 DEG C different from the set temperature, and the temperature adjusting accuracy is 0.1 DEG C.

[0021] Further, the pipes between the second fan and the air inlet and the pipes between the third fan and the air outlet are connected with temperature measuring instruments, humidity measuring instruments and air pressure measuring instruments.

[0022] Further, the air inlet of the standard test box is also connected with a humidifier, which can humidify the cold air entering the standard test box and control the humidity inside the box body.

[0023] According to the second aspect of the present application, a refrigerator fresh-keeping performance evaluation test method is disclosed, which is characterized in that:

[0024] The refrigerator prototype with the product instruction or the manufacturer declaration of the "fresh-keeping" function is used as the "test group" prototype, and the standard test box is used as the "control group" prototype for the refrigerator fresh-keeping test;

[0025] The refrigeration system, the humidifier, the fan and the related detection instruments are powered on to work, and cold air is introduced into the standard test box; the refrigeration system mainly comprises a condenser, a compressor and an evaporator;

[0026] The standard test samples or food materials with the same mass, volume and quality are put into the standard test box and the refrigerator prototype;

[0027] The temperature of the standard test box is adjusted to the same or similar temperature as the "fresh-keeping function" of the refrigerator prototype, and after the operation is completed according to the preset time, the moisture change rate, the vitamin C change rate or the volatile basic nitrogen change rate of the samples in the standard test box and the refrigerator prototype are detected respectively;

[0028] In each measurement period, the stability of the operation state of the standard test box is verified once.

[0029] The detection results of the refrigerator prototype and the standard test box are comprehensively calculated, and the fresh-keeping performance of the refrigerator prototype is evaluated.

[0030] Standard test chamber as a test equipment by measurement, stable performance, can meet the laboratory and related accreditation system for test repeatability, reproducibility requirements, can be used as a benchmark for data comparison between different laboratories or different products of enterprises. Some chemical indicators, such as moisture change, vitamin C change, volatile salt base nitrogen change in different temperature intervals are different, and are affected by many factors, and the results often show nonlinear, which is difficult to study in depth. Therefore, the standard test chamber is introduced for test research, as a “control group” sample machine, by setting the same fresh-keeping temperature and running time as the “test group” sample machine, and the “test group” sample machine under the same test conditions, the test can be carried out at the same time, which can reduce the influence of pure temperature factors and other external factors (such as test environment temperature, humidity, test power supply voltage fluctuation, etc.) on “fresh-keeping” performance, and then evaluate the “fresh-keeping technology” adopted by the “test group” sample machine, and help to study the attenuation of various chemical substances under low temperature.

[0031] The measurement method of moisture change rate is as follows:

[0032] The size of the wool sample used is 75mmx125mm, and the original cloth fiber weight is 330gsm. Take 18 pieces of wool samples from two boxes with the same quality and use time and the same production batch, inject 600g±50g distilled water, and place them in the “test group” sample machine and the “control group” sample machine respectively.

[0033] In the “test group” sample machine, the wool sample is placed in the best position for food preservation in the cold room declared by the manufacturer. If the manufacturer does not declare, the sample is placed in the middle position of the fruit and vegetable box of the sample machine. After 24h of stable placement, it is taken out and weighed as m t1 , and the time is recorded as t t1 : After a period of test operation, it is taken out and weighed again as m t2 , and the time is recorded as t t2 .

[0034] In the “control group” sample machine, the standard test chamber is set to “cold storage type”, the temperature is set according to the temperature interval close to the “test group” sample machine, the wool sample is placed in the middle position of the chamber, and after 24h of stable placement, it is taken out and weighed as m r1 , and the time is recorded as t r1 : After a period of test operation, it is taken out and weighed again as m r2 , and the time is recorded as t r2 .

[0035] At the beginning of the test, the wool sample should be placed in the “test group” sample machine and the “control group” sample machine as much as possible, and the “test group” sample machine and the “control group” sample machine should start and end the test as much as possible. After the test, the wool sample should be taken out as much as possible.

[0036] m t1 With m t2 The difference should not exceed 200g; m r1 With m r2 The difference should not exceed 200g.

[0037] t t2 and t t1 The difference should not be less than 72h; t r2 and t r1 The difference should not be less than 72 hours.

[0038] The weight loss of the prototype in the "test group" was calculated according to formula (1).

[0039]

[0040] In the formula:

[0041] W t The unit of measurement is the weight loss obtained by the prototype in the "test group" test, in g / 24h.

[0042] m t1 The unit is g, which represents the weight of the wool sample after the prototype of the "test group" has been stable for 24 hours.

[0043] m t2 This indicates the weighing mass of the wool sample after the prototype test of the "test group" was completed, in grams.

[0044] t t1 This indicates the time after the prototype of the "test group" has stabilized for 24 hours, in hours.

[0045] t t2 This indicates the time after the prototype test of the "test group" ended, in hours.

[0046] The weight loss of the "control group" prototype was calculated according to formula (2).

[0047]

[0048] W r The weight loss obtained in the "control group" prototype test is expressed in g / 24h.

[0049] m r1 The weight of the wool sample after the "control group" prototype test has been stable for 24 hours is expressed in g.

[0050] m r2 The weight of the wool sample after the "control group" prototype test is completed, in grams.

[0051] t r1The time after the "control group" prototype test is stable for 24 hours, unit: h;

[0052] t r2 The time after the "control group" prototype test is stable for 24 hours, unit: h.

[0053] Finally, W t and W r , W t is divided by W r , that is, W r of the "control group" prototype standard test box is taken as 1, and the corrected W c is calculated as the final result. This calculation can offset the influence of some other factors, such as test environment temperature, humidity, test power supply voltage, quality of different batches of wool samples, and the influence of fluctuations in factors such as water quality. The corrected weight loss of the "test group" prototype is calculated according to formula (3):

[0054]

[0055] In the formula:

[0056] W c represents the corrected weight loss of the "test group" prototype, unit: g / 24h.

[0057] Measurement method of vitamin C change rate:

[0058] After the refrigerator is stable for 2 hours, the kiwi with soluble solids not less than 17% is selected and divided into 3 parts with very close mass and volume. One part is measured for VC content according to GB5009.86-2016 third method and recorded as initial value VC0,

[0059] The other two parts are placed in the "test group" prototype and the "control group" prototype respectively. One of them is placed in the best position for food preservation in the refrigerator compartment declared by the manufacturer of the "test group" prototype. If the manufacturer does not declare, the sample is placed in the middle position of the fruit and vegetable box of the prototype. After 7 days of storage, the sample is taken out and the VC content is measured according to GB5009.86-2016 third method and recorded as VC1. The change rate of VC during storage is calculated according to formula (4) t .

[0060]

[0061] In the formula:

[0062] ΔVC t represents the VC change rate of the sample after storage in the "test group" prototype, expressed in percentage (%);

[0063] VC0 represents the initial VC content of the sample, unit: mg / 100g;

[0064] VC1 represents the VC content of the sample after storage by the "test group" machine, unit: mg / 100g.

[0065] The standard test box is set as the "control group" machine, and is set as "refrigeration type". The temperature is set close to the temperature range of the "test group" machine. The second sample in the other two samples is placed in the middle position of the box. After 7 days of storage, the sample is taken out and the VC content of the sample is measured according to GB5009.86-2016 third rule and recorded as VC2. The change rate of VC in the storage process is calculated according to formula (5) r .

[0066]

[0067] In the formula:

[0068] ΔVC r represents the VC change rate of the sample after storage by the "control group" machine, expressed in percentage (%);

[0069] VC2 represents the VC content of the sample after storage by the "control group" machine, unit: mg / 100g.

[0070] Finally, ΔVC t and ΔVC r are obtained. t ΔVC r is divided by ΔVC r , that is, ΔVC t of the "control group" machine standard test box is taken as 1, to correct ΔVC c of the "test group" machine, as the final result. This calculation can offset the influence of some other factors, such as test environment temperature, humidity, test power supply voltage, and the influence of fluctuations in factors such as the quality, weight and VC content of different batches of kiwifruit purchased. The corrected VC change rate of the "test group" machine is calculated according to formula (6):

[0071]

[0072] In the formula:

[0073] ΔVC c represents the corrected VC change rate of the sample after storage by the "test group" machine, expressed in percentage (%).

[0074] Measurement method of volatile base nitrogen (TVB-N) content:

[0075] After the refrigerator is stably operated for 2 hours, select a beef tenderloin sample (the initial moisture content should be ≤77%, and select fresh beef with a shiny meat quality, bright red color, and slightly dry surface) and divide it into three parts that are very close in mass, volume, and meat quality. One of the three parts is used to test the initial TVB-N, and the TVB-N content thereof is determined according to the first method of semi-micro nitrogen determination in GB 5009.228-2016 (should be no more than 12 mg / 100 g) and recorded as the initial value C0(TVB-N).

[0076] The other two parts are placed in the “test group” machine and the “control group” machine, respectively. One of the samples is placed in the best position for preserving meat food in the refrigerator or freezer room declared by the manufacturer of the “test group” machine. If the manufacturer does not declare, the sample is placed in the middle position of the middle compartment of the refrigerator freezer, and stored for 7 days. After the sample is taken out and thawed at an ambient temperature of 23℃±2℃ for 6 hours, the TVB-N content thereof is determined according to the first method of semi-micro nitrogen determination in GB 5009.228-2016 and recorded as C1(TVB-N).

[0077] The change rate ΔC(TVB-N) of the beef tenderloin sample after being stored in the “test group” machine is calculated according to formula (7). t

[0078]

[0079] In the formula:

[0080] ΔC t (TVB-N) represents the change rate of the volatile basic nitrogen of the sample after being stored in the “test group” machine, expressed in percentage (%);

[0081] C0(TVB-N) represents the initial volatile basic nitrogen content of the sample, with the unit of mg / 100 g;

[0082] C1(TVB-N) represents the volatile basic nitrogen content of the sample after being stored in the “test group” machine, with the unit of mg / 100 g.

[0083] The standard test box is used as the “control group” machine and is set to “frozen type”. The temperature is set to be close to the temperature range of the “test group” machine. The second sample of the other two samples is placed in the middle position of the box and stored for 7 days. After the sample is taken out and thawed at an ambient temperature of 23℃±2℃ for 6 hours, the TVB-N content thereof is determined according to the first method of semi-micro nitrogen determination in GB 5009.228-2016 and recorded as C2(TVB-N).

[0084] The change rate ΔC(TVB-N) of the beef tenderloin sample after being stored in the “test group” machine is calculated according to formula (8). r ​​

[0085]

[0086] In the formula:

[0087] ΔC r (TVB-N) represents the percentage change in volatile basic nitrogen of the sample after storage in the "control group" sample.

[0088] C2(TVB-N) represents the volatile basic nitrogen content of the sample after storage in the "control group" sample, in mg / 100g.

[0089] Finally, ΔC is obtained. t (TVB-N) and ΔC r (TVB-N), using ΔC t (TVB-N) divided by ΔC r (TVB-N), that is, ΔC of the standard test chamber of the "control group" prototype. r (TVB-N) is used as 1 to correct the ΔC of the "test group" prototype. t (TVB-N) is used as the final result. This calculation can offset the influence of some other factors, such as the temperature and humidity of the test environment, the voltage of the test power supply, and the fluctuations in the quality, weight, and TVB-N content of different batches of beef tenderloin. The corrected change rate of volatile basic nitrogen in the "test group" prototype is calculated according to formula (9):

[0090]

[0091] In the formula:

[0092] ΔC c (TVB-N) indicates the revised percentage change in volatile basic nitrogen of the sample after storage in the "test group" prototype, expressed as a percentage (%).

[0093] The present invention has the following advantages:

[0094] The application discloses a refrigerator fresh-keeping performance evaluation test device and method, and relates to the technical field of refrigerator fresh-keeping performance evaluation.

[0095] The standard test box designed in the application can be used as a standard test device, and through special design and use of high-quality sensors and a refrigeration system, the stability of performance that an ordinary household refrigerator cannot achieve can be realized, and as a "control group" machine, very good performance control and reference effects can be obtained.

[0096] The various performance indexes measured by the standard test box can be used as basic reference performance values to compare the fresh-keeping effects of refrigerator products of different specifications or fresh-keeping technologies, and at the same time, the influence of factors other than the fresh-keeping technology, such as temperature, running time, laboratory condition deviation, laboratory personnel operation error and external environmental factors, can be excluded to the maximum extent.

[0097] The "standard test box" designed in the application can be used as a "standard test device", and after equipment measurement, the "standard test box" will meet the requirements of relevant national regulations, can meet the requirements of laboratory and related accreditation systems on test repeatability and reproducibility, and the test results of the "standard test box" can be used for value transfer. BRIEF DESCRIPTION OF DRAWINGS

[0098] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only exemplary, and for those skilled in the art, other drawings can be obtained from the provided drawings without creative labor.

[0099] The structures, proportions, sizes, etc. shown in the specification are only used to cooperate with the content disclosed in the specification, so that those skilled in the art can understand and read, and are not used to limit the conditions that the present application can be implemented, so they do not have technical significance. Any modification of structure, change of proportion relationship or adjustment of size, without affecting the effect and purpose that the present application can produce, should still fall within the scope of the technical content disclosed by the present application.

[0100] Figure 1 A refrigerator fresh-keeping performance evaluation test device connection schematic diagram provided by the embodiment of the present application;

[0101] Figure 2 A refrigerator fresh-keeping performance evaluation test method flowchart provided by the embodiment of the present application;

[0102] In the figure: 1-first fan, 2-condenser, 3-compressor, 4-evaporator, 5-second fan, 6-third fan, 7-standard test box, 8-humidifier. DETAILED DESCRIPTION

[0103] The embodiments of the present application will be described below by specific specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the specification. Obviously, the described embodiments are part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0104] Embodiment 1

[0105] The present embodiment discloses a refrigerator fresh-keeping performance evaluation test device, the device comprises: a standard test box 7, a condenser 2, a compressor 3, an evaporator 4 and a humidifier 8, the condenser 2 is connected with the compressor 3, and the fan is used to dissipate heat of the condenser 2, the compressor 3 is connected with the evaporator 4, and the cold air is blown into the standard test box 7 through the fan, the humidifier 8 is connected with the air inlet of the standard test box 7, and the standard test box 7 is provided with a temperature and humidity adjusting device, which can accurately adjust the temperature and humidity of the standard test box.

[0106] The condenser 2 is adjacent to the first fan 1, and the first fan 1 is used to cool the condenser. The exhaust port of the compressor 3 is connected with the condenser 2, and the suction port of the compressor 3 is connected with the evaporator 4. After throttling and adiabatic expansion, the refrigerant is compressed in the compressor 3, so as to realize the circulation of the refrigerant between the condenser 2, the compressor 3 and the evaporator 4.

[0107] The evaporator 4 is connected with the compressor 3, and the refrigerant absorbs heat and evaporates in the evaporator 4. The second fan 5 is used to blow cold air into the air inlet of the standard test box 7, and the third fan 6 is used to blow the gas with higher temperature out of the air outlet of the standard test box 7. The gas with higher temperature blown out by the third fan 6 is cooled by the evaporator 4 to become low-temperature gas, and then is blown into the standard test box 7 by the second fan 5.

[0108] The standard test box 7 is made of double-layer vacuum glass and foaming material, so as to ensure that the situation in the box can be observed under the condition of sufficient heat preservation. The inner layer of the standard test box 7 is provided with multiple shelves, and various types of food materials can be placed on the shelves. The outer layer of the standard test box 7 is provided with an air inlet at the top and an air outlet at the bottom. The refrigerant exchanges heat with the air in the box outside the standard test box, so as to realize the cooling of the internal space of the standard test box. The standard test box 7 is provided with a temperature adjusting device, which can accurately control the refrigeration performance of the compressor system, so that the actual temperature in the box body and the set temperature differ by not more than ±0.5℃, and the temperature adjusting accuracy is ±0.1℃. The temperature of the standard test box 7 can be adjusted to meet the simulation of different fresh-keeping temperature settings of various refrigerators. The standard test box can adjust and test multiple grades of temperature in the range of (-35℃ to +8℃).

[0109] The pipes of the air inlets and the air outlets are connected with temperature measuring instruments, humidity measuring instruments and air pressure measuring instruments. The temperature detecting instruments and the air pressure detecting instruments connected with the air inlets detect the temperature and the pressure of the gas entering the standard test box 7, and the temperature detecting instruments and the air pressure detecting instruments connected with the air outlets detect the temperature and the pressure of the gas discharged from the standard test box 7, so that the temperature difference can be obtained, and the temperature in the standard test box 7 can be accurately adjusted. The air inlets of the standard test box 7 are also connected with humidifiers 8, which humidify the cold air entering the standard test box 7, control the humidity in the box body, control the actual humidity and the set humidity within ±5%RH, and the humidity setting accuracy is ±1%RH. Meanwhile, the humidity in the box body is continuously monitored.

[0110] The refrigerator fresh-keeping performance evaluation test device disclosed by the embodiment is used as a "control group" machine, and a performance evaluation test for refrigerator fresh-keeping technology is performed under the same conditions as a "test group" machine. The test result of the standard test box is used as a reference value for calculating the final result, which can solve the very critical technical problem in the evaluation of refrigerator fresh-keeping technology. The standard test box 7 is used as a "control group" machine for test research, and the performance is stable, which can meet the requirements of the laboratory and the related recognition system for test repeatability and reproducibility. It can be used as a reference for data comparison between different products in different laboratories or enterprises. At the same time, the same fresh-keeping temperature and running time are set as the "test group" machine, and the "test group" machine is tested under the same test conditions, which can reduce the influence of temperature factors and other external factors (such as test environment temperature, humidity, test power supply voltage fluctuation, etc.) on the "fresh-keeping" performance as much as possible, and then evaluate the "fresh-keeping technology" used by the "test group" machine, which is helpful for studying the attenuation of various chemical substances under low temperature conditions, so that the test result is more stable and has more research value.

[0111] Embodiment 2

[0112] The refrigerator fresh-keeping performance evaluation test method disclosed by the embodiment is as follows:

[0113] The refrigerator machine with "fresh-keeping" function in the product instruction or manufacturer's statement is used as a "test group" machine, and the "standard test box" is used as a "control group" machine for this refrigerator fresh-keeping test;

[0114] The refrigeration system, humidifier 8, fan and related detection instruments are powered on to work, and cold air is introduced into the standard test box 7. The refrigeration system mainly includes a condenser 2, a compressor 3 and an evaporator 4;

[0115] The same food materials in quality, volume and quality are put into the fresh-keeping refrigerator test machine ("test group" machine) and the standard test box ("control group" machine) 7;

[0116] The temperature of the standard test box 7 ("control group" machine) is adjusted to a temperature close to that of the refrigerator test machine ("test group" machine), and the operation is completed according to the preset time. The moisture change rate, vitamin C change rate or volatile base nitrogen change rate of the samples stored in the "test group" machine and the "control group" machine are detected respectively;

[0117] In each measurement period, the stability of the standard test box is verified once;

[0118] The test results of the refrigerator test prototype ("test group" machine) and the standard test box ("control group" machine) 7 are calculated comprehensively, and the freshness performance of the "test group" machine is evaluated.

[0119] The standard test box 7 is a test equipment by measurement, with stable performance, which can meet the requirements of laboratory and related accreditation system for test repeatability and reproducibility, and can be used as a benchmark for data comparison between different products in different laboratories or enterprises. Some chemical indicators, such as vitamin C change, moisture change, volatile salt base nitrogen change in different temperature intervals are different, and due to the influence of many external factors and test condition changes, the results often show nonlinearity, which is difficult to study in depth. Therefore, the standard test box 7 is introduced as the "control group" machine for test research, the same fresh-keeping temperature and running time as the "test group" machine are set, and the test is carried out at the same time under the same test conditions as the "test group" machine, so as to minimize the influence of pure temperature factors and other external factors (such as test environment temperature and humidity, test power supply voltage fluctuation, etc.), which is helpful to study the decay of many chemical substances under low temperature conditions.

[0120] The measurement method of moisture change rate is as follows:

[0121] The size of the wool sample used is 75mmx125mm, and the original cloth fiber weight is 330gsm. Take 18 pieces of wool samples from two boxes with the same quality and use time and the same production batch, inject 600g+50g distilled water into the box, and place them in the "test group" machine and the "control group" machine respectively.

[0122] In the "test group" machine, the wool sample is placed in the best position for food preservation in the cold room declared by the manufacturer, if the manufacturer does not declare, the sample is placed in the middle position of the fruit and vegetable box of the machine, and after 24h of stable placement, it is taken out and weighed as m t1 , and the time is recorded as t t1 : After a period of test operation, it is taken out and weighed again as m t2 , and the time is recorded as t t2 .

[0123] In the "control group" machine, the standard test box is set to "cold storage type", the temperature is set according to the temperature interval close to the "test group" machine, the wool sample is placed in the middle position of the box, and after 24h of stable placement, it is taken out and weighed as m r1 , and the time is recorded as t r1 : After a period of test operation, it is taken out and weighed again as m r2 , and the time is recorded as t r2 .

[0124] At the start of the test, wool samples should be placed into the "test group" prototype and the "control group" prototype as simultaneously as possible; the "test group" prototype and the "control group" prototype should start and end the test as simultaneously as possible; after the test, the wool samples should be removed as simultaneously as possible.

[0125] m t1 With m t2 The difference should not exceed 200g; m r1 With m r2 The difference should not exceed 200g.

[0126] t t2 and t t1 The difference should not be less than 72h; t r2 and t r1 The difference should not be less than 72 hours.

[0127] The weight loss of the prototype in the "test group" was calculated according to formula (1).

[0128]

[0129] In the formula:

[0130] W t The unit of measurement is the weight loss obtained by the prototype in the "test group" test, in g / 24h.

[0131] m t1 The unit is g, which represents the weight of the wool sample after the prototype of the "test group" has been stable for 24 hours.

[0132] m t2 This indicates the weighing mass of the wool sample after the prototype test of the "test group" was completed, in grams.

[0133] t t1 This indicates the time after the prototype of the "test group" has stabilized for 24 hours, in hours.

[0134] t t2 This indicates the time after the prototype test of the "test group" ended, in hours.

[0135] The weight loss of the "control group" prototype was calculated according to formula (2).

[0136]

[0137] In the formula:

[0138] W r The weight loss obtained in the "control group" prototype test is expressed in g / 24h.

[0139] m r1 The weight of the wool sample after the "control group" prototype test has been stable for 24 hours is expressed in g.

[0140] m r2 represents the weight of the wool sample after the end of the "control group" machine test, unit: g;

[0141] t r1 represents the time after the "control group" machine test is stable for 24 hours, unit: h;

[0142] t r2 represents the time after the end of the "control group" machine test, unit: h.

[0143] Finally, W t and W r , W t is divided by W r , that is, W r of the "control group" machine standard test box is taken as 1, and the corrected W c is calculated as the final result. This calculation can offset the influence of some other factors, such as test environment temperature, humidity, test power supply voltage, different batches of wool sample quality, and the influence of water quality factors. The corrected weight loss of the "test group" machine is calculated according to formula (3):

[0144]

[0145] In the formula:

[0146] W c represents the corrected weight loss, unit: g / 24h.

[0147] Measurement method of vitamin C change rate: After the refrigerator is stably operated for 2h, the kiwi fruit with soluble solids not less than 17% is selected and divided into 3 parts with very close mass and volume. One part is determined for VC content according to GB5009.86-2016 third method and recorded as initial value VC0,

[0148] The other two parts are placed in the "test group" machine and the "control group" machine respectively. One of them is placed in the "test group" machine manufacturer's declared best position for food preservation in the refrigerator, and if the manufacturer does not declare, the sample is placed in the middle position of the fruit and vegetable box of the machine. After 7 days of storage, the sample is taken out and the VC content of the sample is determined according to GB5009.86-2016 third method and recorded as VC1. The change rate ΔVC of VC during storage is calculated according to formula (4) t .

[0149]

[0150] In the formula:

[0151] ΔVCt VC0 represents the initial VC content of the sample, unit: mg / 100g;

[0152] VC0 represents the initial VC content of the sample, unit: mg / 100g;

[0153] VC1 represents the VC content of the sample after storage in the "test group" machine, unit: mg / 100g;

[0154] The standard test box is set as the "control group" machine as "cold storage type", and the temperature is set close to the temperature interval of the "test group" machine. The second sample in the other two samples is placed in the middle position of the box. After 7 days of storage, the sample is taken out and the VC content is measured according to GB5009.86-2016 third rule and recorded as VC2. The change rate of VC during storage is calculated according to formula (5) r .

[0155]

[0156] In the formula:

[0157] ΔVC r VC0 represents the initial VC content of the sample, unit: mg / 100g;

[0158] VC2 represents the VC content of the sample after storage in the "control group" machine, unit: mg / 100g;

[0159] Finally, ΔVC t and ΔVC r , ΔVC t is divided by ΔVC r , that is, ΔVC r of the "control group" machine standard test box is taken as 1, to correct ΔVC t of the "test group" machine, as the final result. This calculation can offset the influence of some other factors, such as test environment temperature, humidity, test power supply voltage, and the influence of fluctuations in factors such as the quality, weight and VC content of different batches of kiwifruit. The corrected VC change rate of the "test group" machine is calculated according to formula (6):

[0160]

[0161] In the formula:

[0162] ΔVC c VC0 represents the initial VC content of the sample, unit: mg / 100g;

[0163] Method for measuring volatile base nitrogen (TVB-N) content:

[0164] After the refrigerator is stably operated for 2 h, select a beef tenderloin sample (the initial moisture content should be ≤77%, and select fresh beef with a shiny appearance, bright red color, and slightly dry surface) and divide it into 3 parts that are very close in mass, volume, and meat quality. One of the parts is used to test the initial TVB-N, and the TVB-N content thereof is determined according to the semi-micro nitrogen determination method of GB 5009.228-2016 (first method) (should be no more than 12 mg / 100 g) and recorded as the initial value C0(TVB-N).

[0165] The other two parts are placed in the “test group” machine and the “control group” machine, respectively. One of the samples is placed in the “test group” machine at the best position for preserving meat food in the refrigeration chamber or the freezing chamber as declared by the manufacturer, or in the middle position of the middle compartment of the refrigerator freezer if no declaration is made. After 7 days of storage, the sample is taken out, placed in an environment at 23℃±2℃ for thawing for 6 h, and then the TVB-N content thereof is determined according to the semi-micro nitrogen determination method of GB 5009.228-2016 (first method) and recorded as C1(TVB-N).

[0166] The change rate ΔC(TVB-N) of the beef tenderloin sample after storage in the “test group” machine is calculated according to formula (7). t (TVB-N).

[0167]

[0168] In the formula:

[0169] ΔC t (TVB-N) represents the change rate of the volatile basic nitrogen of the sample after storage in the “test group” machine, expressed in percentage (%);

[0170] C0(TVB-N) represents the initial volatile basic nitrogen content of the sample, in mg / 100 g;

[0171] C1(TVB-N) represents the volatile basic nitrogen content of the sample after storage in the “test group” machine, in mg / 100 g.

[0172] The standard test box is used as the “control group” machine and is set to “frozen type”. The temperature is set to a temperature range close to that of the “test group” machine. The second sample of the other two samples is placed in the middle position of the box. After 7 days of storage, the sample is taken out, placed in an environment at 23℃±2℃ for thawing for 6 h, and then the TVB-N content thereof is determined according to the semi-micro nitrogen determination method of GB 5009.228-2016 (first method) and recorded as C2(TVB-N).

[0173] The change rate ΔC(TVB-N) of the beef tenderloin sample after storage in the “control group” machine is calculated according to formula (8).r (TVB-N)

[0174]

[0175] In the formula:

[0176] ΔC r (TVB-N) represents the percentage change in volatile basic nitrogen of the sample after storage in the "control group" sample.

[0177] C2(TVB-N) represents the volatile basic nitrogen content of the sample after storage in the "control group" sample, in mg / 100g.

[0178] Finally, ΔC is obtained. t (TVB-N) and ΔC r (TVB-N), using ΔC t (TVB-N) divided by ΔC r (TVB-N), that is, ΔC of the standard test chamber of the "control group" prototype. r (TVB-N) is used as 1 to correct the ΔC of the "test group" prototype. t (TVB-N) is used as the final result. This calculation can offset the influence of some other factors, such as the temperature and humidity of the test environment, the voltage of the test power supply, and the fluctuations in the quality, weight, and TVB-N content of different batches of beef tenderloin. The corrected change rate of volatile basic nitrogen in the "test group" prototype is calculated according to formula (9):

[0179]

[0180] In the formula:

[0181] ΔC c (TVB-N) indicates the revised percentage change in volatile basic nitrogen of the sample after storage in the "test group" prototype, expressed as a percentage (%).

[0182] To ensure the stability of the standard test chamber, a stability verification needs to be performed on the standard test chamber once within each metrology cycle. The specific verification method is as follows:

[0183] Step 1: Conduct 10 tests on the standard test chamber according to the "Method for Measuring Moisture Change Rate";

[0184] Step 2: If the "sample mean difference" of these 10 trials 注2 If the result is less than 0.5%, the average of the 10 test results will be denoted as "μ" and the standard deviation as "δ".

[0185] Step 3: If the "sample average difference" of the 10 tests is ≥ 0.5%, then 5 more tests are added, and then in all 15 tests, the 2 tests with the largest absolute value of the difference between the sample and the average are removed, and the average of the remaining 13 tests is recorded as "μ" and the standard deviation is recorded as "δ";

[0186] Step 4: The "μ" value and the "δ" value are the stable values of the standard test box in this measurement period.

[0187] Stability verification of each formal test:

[0188] Step 11: After each "moisture change rate" test, the test result of the standard test box is recorded as "x";

[0189] Step 12: When the "x" value meets the following relationship with the "μ" value and the "δ" value of the standard test box in this measurement period, the "x" value of this test result is valid.

[0190] μ-2δ < x < μ+2δ

[0191] Step 13: If the "x" value of this test does not meet the above requirements, the test is invalid, and one more test should be added (1 group of tests should include 3 valid tests);

[0192] Step 14: If more than one test result is invalid in a group of tests, the group of tests is invalid, and a new group of tests should be performed;

[0193] Step 15: When the "x" value of each test in the group of tests meets the requirements of step 12, the test results of "moisture change rate", "vitamin C change rate", or "volatile salt base nitrogen change rate" using the standard test box as the "control group" sample machine are valid.

[0194] Note 2: "Sample average difference" refers to the average of the sum of the absolute values of the differences between each quantity and the average in the 10 test sample data.

[0195] In the research of refrigerator preservation, real food materials such as spinach, tomatoes, and beef are often used for test research, but the individual differences of plants or meat are large, often causing large fluctuations in test results. Using the standard test box 7 as the control group for testing, when using real food materials for research, a portion of the same quality, volume, and quality is placed in the refrigerator sample machine and the standard test box 7, respectively. The test results obtained will be more stable, reducing the influence of the organism itself, and making the test results more valuable for research.

[0196] The current different refrigerator products claimed to have different refrigeration and preservation temperature (may be between -3℃ to +8℃), the standard test box 7 can be introduced to set multiple temperature intervals independently, and the refrigeration temperature can be set at a temperature close to the refrigeration and preservation technology of the refrigerator prototype 注3 , which helps to reduce the influence of temperature change. The standard test box can set the temperature according to the actual preservation temperature of the measured prototype, for example, for a preservation refrigerator with a preservation temperature of “-2~+2℃”, the temperature of the standard test box can be set to 0℃; for a preservation refrigerator with a preservation temperature of “0~+4℃”, the temperature of the standard test box can be set to +2℃, thereby making the temperature of the standard test box close to the temperature of the measured prototype, eliminating the preservation effect brought by low temperature only, so that refrigerators with different preservation temperatures can be compared with each other for their preservation performance, and the preservation effect brought by temperature only can be offset by the standard test box, so that the preservation technology with different temperatures can be more reasonably evaluated.

[0197] Note 3: “Close temperature” refers to, for example, if the refrigerator prototype is at a certain constant temperature, the standard test box is set to this temperature; if the refrigerator prototype operates within a certain temperature range, the standard test box is set to the average value of the temperature range.

[0198] To verify the preservation technology of the measured prototype, the corresponding storage interval of the standard test box is set to a temperature close to that of the measured prototype to offset the preservation effect brought by low temperature only.

[0199] The “standard test box” can be set to “refrigeration type” and “freezing type”. The standard test box can adjust and test multiple temperatures within the range of (-35℃~+8℃).

[0200] In the “refrigeration type” mode, the temperature can be set between -5℃ and +8℃ to correspond to various refrigerator products with refrigeration and preservation function on the current market; when performing refrigeration and preservation test, the temperature can be set according to the preservation temperature of the “measured prototype”, for example, if the preservation temperature of the measured prototype fluctuates within a temperature range, the temperature of the “standard test box” is set to the average temperature of the temperature range of the “measured prototype” (for example, for a “measured prototype” with a preservation temperature within “0℃~+2℃”, the temperature of the “standard test box” is set to +1℃);

[0201] In the “freezing type” mode, the temperature can be set between -35℃ and -5℃ to correspond to various refrigerator products with freezing and preservation function on the current market; when performing freezing and preservation test, the temperature can be set according to the preservation temperature of the “measured prototype”, for example, if the preservation temperature of the measured prototype fluctuates within a temperature range, the temperature of the “standard test box” is set to the average temperature of the temperature range of the “measured prototype” (for example, for a “measured prototype” with a preservation temperature within “-10℃~ -12℃”, the temperature of the “standard test box” is set to -11℃).

[0202] By using the standard test chamber 7 as the "control group" prototype and conducting performance evaluation tests on refrigerator preservation technology under the same conditions as the "test group" prototype, the repeatability and reproducibility of the test results are improved. This allows for the transfer of measurement values ​​and mutual recognition of data between test results from different laboratories, and enables the evaluation of the preservation performance of refrigerator products using different preservation technologies.

[0203] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for evaluating the freshness-keeping performance of a refrigerator, characterized by, The utility model relates to a standard test box refrigeration system and humidity device, and a method for testing the fresh-keeping performance of a refrigerator. The standard test box refrigeration system comprises a standard test box, a refrigeration system and a humidifier. The refrigeration system mainly comprises a condenser, a compressor and an evaporator. The condenser is provided with a first fan adjacent to the condenser to dissipate heat from the condenser. The condenser is connected to the compressor, and the compressor is connected to the evaporator. The humidifier is connected to the air inlet of the standard test box. The standard test box is provided with a temperature and humidity adjusting device to precisely adjust the temperature and humidity of the standard test box. The evaporator absorbs heat to evaporate the refrigerant. The second fan blows the cooled air from the evaporator into the air inlet of the standard test box to cool the standard test box. The third fan blows the air in the standard test box out of the air outlet of the standard test box. The second fan and the third fan are connected to the temperature detector, the humidity detector and the air pressure detector. The temperature detector and the air pressure detector connected to the air inlet detect the temperature and pressure of the air entering the standard test box. The temperature detector and the air pressure detector connected to the air outlet detect the temperature and pressure of the air exiting the standard test box. The temperature difference is obtained to facilitate the precise adjustment of the temperature in the standard test box.

2. The method for evaluating the freshness-keeping performance of a refrigerator according to claim 1, wherein The refrigeration system, the humidifier, the fans and the temperature detector, the humidity detector and the air pressure detector are powered on to work and supply cooled air to the standard test box.

3. The method of claim 1, wherein the test is performed for 3 days. The same standard test samples in terms of mass, volume and quality are placed in the standard test box and the refrigerator prototype.

4. The method of claim 1, wherein the method is performed at a temperature of 0°C to 10°C. The temperature of the standard test box is adjusted to the same or similar temperature as the fresh-keeping function of the refrigerator prototype. After the operation is completed according to the preset time, the moisture change rate, the vitamin C change rate or the volatile salt base nitrogen change rate of the samples in the standard test box and the refrigerator prototype are detected. The stability of the standard test box is verified once in each measurement period. The detection results of the refrigerator prototype and the standard test box are comprehensively calculated to evaluate the fresh-keeping performance of the refrigerator prototype. The exhaust port of the compressor is connected to the condenser, and the suction port of the compressor is connected to the evaporator. The refrigerant is compressed in the compressor to realize the circulation of the refrigerant between the condenser, the compressor and the evaporator. The standard test box is made of double-layer vacuum glass and foaming material. The inner layer of the standard test box is provided with multiple shelves. The top of the outer layer of the standard test box is provided with an air inlet, and the bottom is provided with an air outlet. The refrigerant exchanges heat with the air in the standard test box through the evaporator outside the standard test box. The temperature adjusting device is provided on the standard test box to accurately control the refrigeration performance of the compressor system. The actual temperature in the box body differs from the set temperature by no more than ±0.5℃, and the temperature adjustment accuracy is ±0.1℃.

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