EXPERT SYSTEM FOR REFRIGERATION UNIT DIAGNOSIS

Functional diagram of the compression refrigeration unit is considered. Facts and classic pro-duction rules for the knowledgebase are compiled. The expert system for this electrical equip-ment functional diagram diagnosis is realized.

Back Analysis of a Horizontal Geothermal Plant Implemented in a Wine Production Process

The Salcheto winery has undertaken a process of reduction of its primary energy consumption and the implementation of green energy technologies. They adopted solar photovoltaic, wood biomass, and geothermal energy sources. A horizontal ground source heat exchanger (GSHE) plant is used to cool a part of the pressed grapes and control the wine production temperature. The goal of this work was to investigate some technical issues of the plant and to increase the efficiency of the whole system. The first step was the evaluation of the actual operating conditions of the GSHE plant, by performing a thermal response test. The results allowed us to find the thermal diffusivity of 3.5 × 10−7 m2/s, and the calculation with the IGSHPA standard indicated a cooling performance of about 6 kW. A survey during the harvest highlighted a peak power of 6 kW. Therefore, to improve the plant, some modifications were proposed and analyzed. In the new layout, the geothermal plant serves the condenser of the refrigeration unit, allowing cooling of the all production lines, instead of only one. The peak power was evaluated as 32 kW, and the GSHE can fulfil this, up to 18 kW. For higher power, the evaporative tower will supply the remainder, covering a maximum of 45%. Furthermore, the refrigeration unit may cover the cooling requirements of the entire residential and office building, without other plant improvements.

Artificial ground freezing using solar-powered thermosyphons

Thermosyphons are an artificial ground-freezing technique that has been used to stabilize permafrost since the 1960s. The largest engineered structure that uses thermosyphons to maintain frozen ground is the Trans Alaska Pipeline, and it has over 124,000 thermosyphons along its approximately 1300 km route. In passive mode, thermosyphons extract heat from the soil and transfer it to the environment when the air temperature is colder than the ground temperature. This passive technology can promote ground cooling during cold winter months. To address the growing need for maintaining frozen ground as air temperatures increase, we investigated a solar-powered refrigeration unit that could operate a thermosyphon (nonpassive) during temperatures above freezing. Our tests showed that energy generated from the solar array can operate the refrigeration unit and activate the hybrid thermosyphon to artificially cool the soil when air temperatures are above freezing. This technology can be used to expand the application of thermosyphon technology to freeze ground or maintain permafrost, particularly in locations with limited access to line power.

Improving energy efficiency of cold storage

Saving resources and energy in refrigeration systems is one of the main vectors of development of the national economy of our country. One of the promising ways to solve these problems is the use of energy efficient refrigeration machines. The article discusses the main issues on the organization of energy efficient storage. In particular, the main recommendations for the design of the storage building are given; an analysis of the energy efficiency of refrigeration machines with and without VFD (variable frequency drive) is given; the main aspects of the operation of the condenser of the refrigeration unit are considered. Keywords: ANNUAL ENERGY CONSUMPTION, REGULATION, ENERGY EFFICIENCY

IOT Warehouse Monitoring System

Aiming at monitoring the temperature and humidity inside the refrigerator and managing information of the refrigerator internal. In this system, there is a design of an intelligent monitoring system based on the Internet of thing, realized monitoring temperature and humidity inside the refrigerator unit and the intelligent cargo identification process by using advanced technologies like MQTT, Cloud Computing, sensor technology and the wireless communication technology. The proposed system used an ESP32 as main control unit, DHT22, E18 Infrared sensor. The system is very powerful to monitor refrigeration unit from anywhere and anytime using mobile application. This system will be capable to do control and monitoring through mobile and web application. We will achieve the good result to data monitoring such as Temperature, humidity and door status with MQTT. It is satisfied with the performance through the analysis of monitoring system and experiment results for the designed refrigerated unit monitoring system. Moreover, this proposed system has main advantages which are minimize the human effort for the manual monitoring and loss due to uncontrolled environment.

THERMAL INTEGRATION OF COMPRESSION REFRIGERATION UNITS IN DAIRY FACILITIES

The heat integration of an ammonia compression refrigeration unit, that is used in different dairy facilities, was carried out by the pinch analysis methods. The schematic diagram of such unit with a cooling capacity of 1000 kW was taken as a basis. The main cycle temperatures, refrigerant consumption and its specific heat capacity were calculated for a given refrigerating capacity. Based on these data, a stream table was formed, that included a hot stream of a refrigerant – ammonia – and also two cold streams: water for chemical water treatment and water for technology. The hot stream of ammonia was divided into three streams: cooling of ammonia vapors, condensation and subcooling. Heat capacities flowrates and heat loads (stream enthalpy change) of the streams were determined. The minimum temperature difference in heat exchangers DTmin = 8°С was determined on the basis of technical and economic calculations for this process. The composite curves were plotted for the minimum temperature difference. The pinch temperatures were determined by the problem table algorithm for the hot and cold streams. The minimum values of hot and cold utilities load (QHmin and QСmin) were determined. The heat recovery capacity was determined, which was 701.8 kW. A grid diagram was built and heat exchangers are arranged in accordance with CP and N rules. The retrofit of process flowsheet is proposed on the basis of the grid diagram that includes the installation of three heat exchangers, one cooler and two heaters to achieve the target temperatures and flow rates. The use of Alfa Laval plate heat exchangers is proposed as heat exchange equipment. The payback period of the design is about two years.