Required Refrigeration Capacity Research Articles

Design and calculation of cold storage capacity of 10 tons for tuna commodity

The Ministry of Maritime Affairs and Fisheries, Republic of Indonesia, urges economic stakeholders to maximize increasingly open export opportunities. With an abundance of fishery products in Indonesian waters, it must be supported by adequate facilities, one of which is the availability of cold storage, which maintains the quality of fishery products. In this study, the design of the cold storage was carried out by measuring the size of the cold storage and using the calculation of the cooling load, the calculation of cooling capacity, the calculation of the P-h diagram, and the cost estimate. The results of this study include cold storage design dimensions of 420 m3 with a long length and tall of 15×7×4 m3 made from insulation materials of polyurethane, stainless steel, and plaster. The cooling load data for the cold storage, when the product (tuna) is cooled and filled, is 3,707,444.3 kJ every 24 hours. A ton of refrigeration absorbs 12,660 kJ per 24 hours, equaling 16.3 tons of required refrigeration capacity. Meanwhile, under normal operating conditions, the total cooling load is 759,427.588 kJ per 24 hours. After calculating the cooling load, it was discovered that the initial design, which only had a capacity of 10 tons during the refrigeration process, could accommodate a cooling capacity of up to 16.3 tons. The cooling capacity of cold storage is 23.9 kW or 81.400 Btu/h. P-h diagram calculation of compressor cooling load is 0.7 kW, and the cooling load total from the evaporator to keep air room temperature of cold storage 0 °C is 0.43 kW. Estimated cost total for materials of cold storage design is USD 128,655. Highlights Refrigerator facilities are still limited in reaching remote coastal areas The cooling system must start using renewable energy Cold storage is used to maintain the quality of fishery product so that they remains in good condition From the calculation results, knowing the total cooling load when the cold storage is working, knowing the total cooling capacity of the cold storage when it is used as a fish storage refrigerator, and knowing the total estimated operational costs of the cold storage

ВИКОРИСТАННЯ НАДЛИШКУ ХОЛОДОПРОДУКТИВНОСТІ ХОЛОДИЛЬНИХ МАШИН ПРИ ОХОЛОДЖЕННІ ПОВІТРЯ НА ВХОДІ ГТУ

The processes of the gas turbine inlet air cooling by exhaust heat conversion chillers, which utilizing the gas turbine exhaust gas heat, converting it into cold were analyzed. The use of two-stage air cooling has been investigated: to a temperature of 15°C – in an absorption lithium-bromide chiller and below to a temperature of 10°C – in an ejector chiller as stages of a two-stage absorption-ejector chiller. To simulate air cooling processes, the program "Guentner Product Calculator", one of the leading manufacturers of heat exchangers "Guentner", was used. The possibility of using the accumulated excess refrigeration capacity of a combined absorption-ejector chiller, which is formed at reduced current heat loads on air coolers at the gas turbine inlet, to cover the refrigeration capacity deficit arising at increased heat loads due to high ambient air temperatures has been investigated. The refrigeration capacity required to the gas turbine inlet air cooling was compared to an excess refrigeration capacity which excess of the current heat load. The considered air cooling system provides pre-cooling of air at the gas turbine inlet by using the excess refrigeration capacity of the absorption-ejector chiller, accumulated in the cold accumulator, to provide the required refrigeration capacity of the air pre-cooling booster stage. The simulation results proved the expediency of the gas turbine inlet air cooling using the accumulated excess refrigeration capacity of the combined absorption-ejector chiller. The proposed solution reduces by about 50% the design refrigeration capacity and, accordingly, the cost of the installed absorption lithium-bromide chiller, which acts as a high-temperature stage for cooling the ambient air at the gas turbine inlet.

Cooling Load Calculation for Efficient Cold Storage of Fresh-Cut Yam Bean

Fresh-cut yam beans are highly perishable and required to be stored in a cold room that is maintained at 5°C and relative humidity of 90%. Nonetheless, the cold storage can be an unnecessarily high energy user if the refrigeration equipment is not selected appropriately to match the actual cooling load. This is not favorable for the fresh-cut processors that are mostly small and medium enterprises (SMEs). In this study, the design of cold storage for the fresh-cut yam bean was presented to comply the necessary requirement by food manufacturing standard. Based on the design, the correct calculation of the cooling load by considering all the possible heat sources was performed. The resulted cooling load was 53239.30 kW with 36% heat load sourced from fresh-cuts, 22% from transmission, 18% from infiltration, and the rest from workers, lighting, ventilation and defrosting. The designated cold storage for 240 kg fresh-cuts has the dimension of 4.9 x 2.5 x 3 m in length, width and height and accommodates adequate space for the workers and necessary equipment as well as features to minimize heat gains. The required refrigeration capacity was 3.33 kW and serve as basis for the selection of refrigeration equipment.

CFD modeling and optimization of pre-cooling conditions in a cold room located in the South of Tunisia and filled with dates.

Thermal and aerodynamic study is performed on a cold store room installed in the south of Tunisia and filled with about 11 tons of dates to be cooled from harvest conditions to about 5°C. The main object of this study is to define the suitable precooling conditions leading to homogeneous storage temperature inside the room. The considered cold room is of about 67m3 of volume and equipped with an evaporator giving the required refrigeration capacity. Three-dimensional CFD model is established taking into consideration the local environmental parameters. The model SST k-ω is used to analyze the air turbulences. For normal design of the cold store room and during a precooling period of 40h, the air velocity and temperature are determined in the different locations inside the room and vary between 0.25-7m/s and 3-6°C. While the product temperature remains higher than the required storage conditions of about 12°C. A new cold store room design is proposed using specific aerodynamic air deflector profiles. That permits to improve the heat transfer between the cold air and product. The precooling period is reduced of about 10h and the average product temperature reaches 6°C.

Experimental characterization and modelling of refrigeration of pork carcasses during transport under field conditions

Measurements of air and product temperatures were conducted at different positions in a semi-trailer loaded with 480 warm half-carcasses of pork (core temperature ∼13 °C, surface temperature ∼7 °C). The temperature evolution of 8 instrumented half-carcasses during transport show that the core temperature decreased significantly and reaches 7 °C in most of half-carcasses after 9 h, whereas all the measured temperature of product surfaces decreased to 6 °C. Analysis of the cooling kinetics of the carcasses was conducted to determine the convective heat transfer coefficient (average value 7.7 W m−2 K−1 and standard deviation 1.8 W m−2 K−1). A simplified model based on an analytical solution was proposed to predict the core and average temperature changes during transport. The required refrigerating capacity was estimated for different loading ratios of warm and cold carcasses (Tc of 15 °C and 7 °C, respectively) in a semi-trailer. It was shown that the studied semi-trailer had sufficient refrigerating capacity to evacuate the heat, whatever the ratio of warm carcasses.

Modeling of cold room driven by an absorption refrigerator in the south of Tunisia: A detailed energy and thermodynamic analysis

This paper deals with the performance modeling of a cold room used for food storage in the south of Tunisia. The cooling process is properly carried out in the purpose to insure high quality and safety of products. An overview of the system is presented. A theoretical model is developed discerning the thermal load for the date's refrigeration. The heat supplied to the generator is provided by a solar thermal collector. An error of about 1.5% is noticed between theoretical and experimental results. It could be well-thought-out as a good agreement. To make the program of universal usage, an interface application is carried out to predict the required cooling load for any considered operating conditions. Furthermore, the main optimal parameters could be achieved by improving the room wall insulation or controlling the working conditions (working hours, number of workers). The required refrigeration capacity is generated in the evaporator of an ammonia/water absorption system. A computer code based on thermodynamic properties of ammonia-water mixture is performed to optimize the refrigeration cycle performances. For an optimal coefficient of performance (COP) of about 0.74 and a cooling load of 8 kW, the required heat flux in the generator is about 11 kW.

Commissioning Test Results of Variable-Temperature Helium Refrigerator/Liquefier for NIFS Superconducting Magnet Test Facility

The superconducting magnet test facility in the National Institute for Fusion Science has been upgraded for excitation tests at a wide temperature range and a higher magnetic field of 13 T. As part of the upgrade, the helium refrigerator/liquefier that operated for 24 years was replaced with a variable-temperature helium refrigerator/liquefier. The required liquefaction rate is 250 L/h, and the required refrigeration capacity is 600 W at 4.5 K, same as the previous one. In addition, it has a new feature that can supply helium gas of a wide temperature range. The typical design cooling capacity is 1 kW under the condition of 20-K supply/30-K return and 1.5 kW under the condition of 40-K supply/50-K return. After the replacement, a series of commissioning tests were performed under the various operational conditions. From the results, the satisfactory thermodynamic performance was confirmed. In the future, it is expected that the substantial progress will be made in the development of large-scale superconducting magnets with advanced superconductors such as high-temperature superconductors and MgB2. The design of the variable-temperature helium refrigerator/liquefier and the results of the commissioning tests are reported in detail.

Experimental investigation of a MnCl2/CaCl2-NH3 two-stage solid sorption freezing system for a refrigerated truck

A MnCl2/CaCl2-NH3 two-stage solid sorption freezing system consisting of a MnCl2 sorption bed, a CaCl2 sorption bed, an evaporator and a condenser is established for a refrigerated truck, for which the required refrigerating capacity is 1.13 kW at a refrigerating temperature of −5 °C. Composite adsorbents of MnCl2 and CaCl2 developed by expanded natural graphite treated with sulfuric acid are utilized. The sorption/desorption process and the resorption process are coupled in the two-stage cycle. The experimental results show that the maximum refrigerating capacity of 1.25 kW and COP (coefficient of performance) of 0.143 are obtained at a resorption time of 120 min when the hot air and refrigerating temperatures are 230 °C and −5 °C, respectively. In addition, the refrigerating capacity of 1.19 kW is achieved even when the hot air temperature is as low as 210 °C, and such a result can satisfy the requirement for transporting fresh goods. The refrigerating capacity is 1.32 kW when the hot air and refrigerating temperatures are 270 °C and −10 °C, respectively, and the data are higher than the required refrigerating capacity. However, for refrigerating temperatures of −15 °C and −18 °C, the refrigerating capacity experimentally obtained could meet the requirement only when a truck is utilized for long-distance transportation.

Study on MnCl2/CaCl2–NH3 two-stage solid sorption freezing cycle for refrigerated trucks at low engine load in summer

A novel MnCl2/CaCl2–NH3 two-stage solid sorption freezing cycle is designed and established for the refrigerated truck with the rated power of 80kW. The conventional sorption/desorption process and the resorption process are combined in the two-stage cycle. Theoretical analysis shows that such a cycle could adapt to the low heat source temperature and the high cooling temperature of the sorption beds very well, which is quite essential for the truck when the running speed and the load are low in summer. The expanded natural graphite treated with sulfuric acid (ENG-TSA) is chosen as the matrix, and composite adsorbents of MnCl2/ENG-TSA and CaCl2/ENG-TSA are developed. The hot air heated by the electric heater is used to simulate the engine exhaust gas to drive the system. When the hot air, the ambient air and the refrigerating temperature are 230°C, 30°C and −5°C, respectively, the average refrigerating capacity is 2.2kW in the sorption process. Correspondingly, the COP and SCP are 0.13 and 91.7W/kg, respectively. The average refrigerating capacity of 1.1kW in one cycle is gotten, which could meet the required refrigerating capacity of the light refrigerated truck at the low engine load engine in summer.

Study on the Effect of the Evaporator Area on the Heat Transfer Performance in the Gravity Feed Liquid Refrigeration System

In order to study the effect on heat transfer performance of evaporator in the gravity feed liquid refrigeration system the different evaporator area, the simulation procedure is worked out. The procedure uses the visual basic language. The procedure can figure out the heat transfer coefficient and the temperature difference in different evaporator area and evaporating temperature with the required refrigerating capacity. Through simulation calculation, when the area is 80% of the original design area of evaporator, the evaporator of the heat transfer coefficient and heat transfer temperature difference is the most reasonable and the evaporator of the refrigerating capacity can meet the requirements of cold storage. The program provides the reliable data for the gravity feed liquid cooling system optimization.

Determination of the refrigerating capacity of cryogenic gas machines for cooling current leads containing high-temperature superconductors

A method of calculation of current leads containing high-temperature semiconductors and cooled by cryogenic gas machines (cryocoolers) has been proposed. The method is based on subdivision of current leads into individual portions (sections) differing in the character of traversal of the current and cooling conditions. The results of the change in the required refrigerating capacity of the coolers operating at different temperature levels as a function of the length and arrangement of the sections have been shown. The distinctive features of the variation in the temperature and the heat flux along cryocooler-cooled current leads have been analyzed.