The article presents the results of research on the problem of increasing the energy efficiency of small refrigeration machines. Approaches and algorithms of evaluating the technical condition of these cars are given.
Key words: small refrigerating machines, energy efficiency, condition monitoring
One of the urgent tasks in the improvement of refrigeration equipment, including small refrigeration machine (MHM) of compression type, include household refrigeration appliances, the challenge is finding solutions to increase their energy efficiency, the ways of reduction specific energy consumption of these machines during operation are pointed out. Most small refrigerating machines do not have the means to control changes in their energy efficiency due to improperly operating conditions and natural temporal changes in the components of the refrigeration unit and the refrigeration Cabinet . The number of these refrigerators are widely used in households, hotels and restaurants, enterprises of public and fast food, the enterprises of meat, dairy and fish industry, the storage of products in distribution centers, grocery and vegetable stores very large.
The total power consumption of these devices, for example for a town with a population of 200 thousand people, is approximately100 thousand kWh/day or approximately 3 million kWh per month.
Possible performance loss  can be up to 10 % of the power consumed, i.e. 0.3 million kWh per month. For conditions the cost of electricity is 3 cost of 1 kWh of losses in money spends may amount to about 0.9 million rubles. per month. For a city with a population of 1 million people, the loss may reach for about 4.5 million rubles a month.
This is a significant loss that should be excluded or minimized. To achieve this objective by monitoring the technical condition  of the refrigerator during operation in a timely manner and eliminate it causes of the increase in their consumption. We perform the study the above issues .
One of the methods for detecting changes (into specification data) specific (daily, annual) energy consumption is a method of measuring performance of the refrigerator prior the usage process and after a regulated period of operation and detection of changes in these parameters .
The following is a variant method of assessing energy efficiency in a small refrigeration machine in the process of its operation.
The method presented in the idea of the algorithm is the sequence of actions that form the basis of the program of the microprocessor unit designed for monitoring thermal power performance of a refrigeration machine. The program provides automatic measurement of the current state of the refrigerator that we can compare the processes of actual performance of work with a nominal mode.
The algorithm is presented in figure 1 and consists of the following steps:
- Creating a standard (normalized) test conditions at the beginning of operation of the refrigerator.
- Measurement of the basic characteristics of the work of MCM.
- The storage of the measurement results.
- Enable timer operation.
- Determining expiry the period of service for maintenance (specifications).
- Creation of standard test conditions.
- Measurement of actual performance.
- Comparison of baseline and actual performance.
- Display the results of the comparison.
- Then the cycle repeats: is the timer operating time, etc. (items 4,5,6,7,8,9).
Another option for assessing the technical state of the model can be run on the principle of «control of the technical condition of the refrigerator by average power consumption» .
Fig. 1. Algorithm for monitoring the technical condition of mkhm
In this embodiment, the monitoring programs includes the following steps:
- Before operation of the refrigeration machine, temperature of the ambient air, without loading the refrigerator cabinet with food measured ambient temperature and measured power consumption for a few (3–5) cycles of operation of the compressor in the steady state.
- Calculated average daily consumption.
- The memory controller in written, the initial average of daily consumption and temperature of the surrounding air.
- Timer switches the countdown operation.
- After start signal the need to perform routine maintenance of refrigerating machines (refrigerator off, clean, clean products and running 2–3 cycles in the steady state) is identified.
- Measurements to be carried out for 3–5 of the cycle indices of energy consumption and ambient temperature.
- Calculated average of daily consumption is stated. The refrigerator is loaded with food and operated and all indicators are registered.
- Corrected if necessary, all calculated data, to state that the actual daily power consumption based on the ambient temperature of the basic, primary measurement.
- Compares actual, planned value specific energy MXM.
- Next, the results of comparisons are pointed out.
The same is true for the algorithm of evaluating the technical condition of the refrigerator according to the criterion of «the Ratio of working time» .
The algorithm allows the researchers to evaluate the technical condition of MHM and to detect deviations in the work without placing the refrigerator in a specialized stand, monitor under operating conditions.
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