This article presents a preliminary thermodynamic evaluation of refrigeration system using phase change materials (PCM) for defrosting. The objective this study is to highlight the potential heat recovery during operation and its subsequent use in defrosting process. analyzed energetically, considering both cooling cycles PCM-RT 35 HC. Input data were experimentally measured on vapor-compression installed freezing chamber located university campus. analysis includes following refrigerants:...

This case study analyzes a cryogenic air separation unit (ASU) with production of V˙O2=58,300 [m3Nh] gaseous oxygen concentration greater than 98.5%, operating in Romania on steel plant platform. The goal the paper is to provide an extensive model exergetic analysis that could be used optimization procedure when decisional parameters are changed or structural design modifications implemented. For each key part Air Separation Unit, product and fuel were defined and, based their...

Polymerase chain reaction (PCR) method was coupled with a DNA extraction to enumerate Campylobacter spp. from poultry gastrointestinal tract samples. Three experiments were conducted that included: 1) Development of standard curve related bacterial primers; 2) Design cell/genomic protocol isolate complex samples such as feces; and 3) Comparison PCR quantification plate count methodology. The using primers for created extracted environmental isolates linear range (R2 > 0.95) high specificity...

Abstract In the present paper, performance and exergy analysis for a vapor compression refrigeration system (VCRS) operating with eco-friendly refrigerants such as R1234ze R1234fyare tested under different operation conditions to change recently worked R-134a. An through is performed guide thermodynamic improvement VCRS. Additionally, comprehensive study conducted examine effects of subcooling temperature on destruction in all components The compressors, condenser, evaporator expansion...

One of the main factors in poultry house is maintaining a standardized microclimate. The quality product output final result depends precisely on indicators air parameters. Poultry during its maintenance requires significant efforts and technological solutions. In this regard, authors improved microclimate system environment by installing exhaust fans side wall total number 8 units. CFD modeling using ANSYS Fluent powerful tool for predicting flow scheme considered an alternative to...

The paper aims to investigate how improve the performance of a refrigeration system (Rs) that equips cold room, by incorporating phase change materials (Phase Change Materials - PCMs) in these systems, study has not yet been extended experimentally. is carried out on room within National University Science and Technology Politehnica Bucharest Faculty Mechanical Mechatronics Engineering, Department Thermodynamics, Engines, Thermal Refrigeration Equipment. This equipped with mechanical vapour...

The research carried out in this paper aimed to create a communication network for fleet of agricultural vehicles by means which transmit and receive information on the status work, working time, processed areas, number machines used much more necessary information. Communication is based GSM WiFi standards, bring most secure security standards data protection network. major advantage solution presented that all important concentrated one place. proposed system consists mobile device routes...

Abstract The study focuses on obtaining hot water above 80°C for industrial purposes. Compared to the electrical heating use of a heat pump appears much more efficient. A comparative analysis using different refrigerants is carried out. cold source waste from an process. exergetic reveals advantages and weaknesses CO 2 as refrigerant. Based exergy destruction concept several schematics two-stage Heat Pumps are considered. For high temperature heating, Pump system represents promising solution.

In the paper, a thermodynamic analysis of an air conditioning system necessary to store quantity 500 kg apricots at temperature 10°C and humidity 90% in fruit warehouse was aimed at. The storage facility is cooled by means handling unit (AHU). energetic exergetic carried out on that treats mixture fresh recirculated for various fractions ranging from 0 100%, thus being able perform finer operation installation under different working conditions. Based exergy analysis, loss estimated each...

The paper aims to compare and choose the most suitable criteria equation for computation of convective heat transfer coefficient on refrigerant side evaporator. comparison is carried out by considering a given air handling unit equipped with specific evaporator operating R134a. A mathematical model given. results obtained equations available in work Shah (1982), Gungor Winterton (1987) Kandlikar (1999) have been compared. first criterion (1982) selected because it leads value pipe length...

In this paper the evaporator from air handling units (AHU) is being studied, connected to an conditioning installation with mechanical compression of vapors, existing within Thermodynamics department. a previous analysis, heat exchanger (HEX) was checked see if it complied cooling capacity relative exchange surface by finding specific criteria equations. A follow-up article calculate based on thermodynamic cycle, what happens refrigerant replaced other new refrigerants in field order improve...

The study is looking for the optimal configuration of an air-to-water heat pump capable heating water in a flow-return system. Carbon dioxide used as working agent. In optimization strategy, exergy analysis considered. Using analysis, magnitude and location any functional or constructive malfunction can be revealed. First, standard one-stage system Due to high destruction throttling valve, efficiency improved by coupling it with auxiliary one. process undertaken internal...

The industrial use of cryogenic air separation units started more than 130 years ago. Cryogenic produce oxygen, pure nitrogen and argon in liquid and/or gaseous state. Different configurations these plants lead to different quantities gas products. In addition, product purity is also affected by the proposed scheme. As a result, paper analyzes variants installations for binary mixtures based on Linde process. By comparing energy indices constructive considerations, plant with external...

Abstract The paper deals with the design and simulation of a gas-water heat exchanger used for heating purposes. represents gas-cooler/water heater transcritical CO 2 pump. log-mean temperature difference NTU-ε methods are comparatively analyzed. transfer area can be calculated through both but true strength what makes when using method is that based on it behaviour an existing easily performed.

Solar flat plate collectors are commonly used to transform solar energy into thermal one by heating a heat transfer fluid (HTF). The available the user is characterized certain capacity and temperature level. Comparing case of single collector, when higher required in process, more should be coupled parallel, so that HTF mass flow rate increased, exiting collector at same temperature. Another may encountered process requires HTF, but In this last case, series connection considered. aim...

Abstract The study is looking for the optimum configuration of a system that requires refrigeration and heating. An ammonia refrigerator separated from R152a heat pump are first considered. Water hot carrying fluid. Based on exergy analysis, points out location magnitude each operational malfunction, an optimization strategy Following procedure two initial systems coupled by using condenser refrigerating unit to preheat water. Due destruction in water preheating condenser, replaced CO 2 ....

The use of organic Rankine cycles (ORCs) is a viable solution for the recovery waste heat. For an air separation unit (ASU) with production V˙O2=58300mN3/h operating in Romania, value utilization heat transferred to cooling system compression area represents 21% global electrical energy input. To recover this thermal and transform it into mechanical energy, ORC was proposed. maximize power, exergy analysis performed. Exergy used choose most suitable fluid find optimum constructive structure...

In the paper we presented a comparative analysis of effect refrigerant used on operation and performance heat pump with water-water regeneration. Various sensitivity studies are comparatively for some eco-friendly refrigerants (R290, R600a, R454C, R152a) R407C. Based energetic analysis, energy destruction loss were estimated each device, depending destination operating regime. Graphic numerical results presented. conclusion, defined coefficient based efficiency is The interest study...

Mathematical model for designing the surface geometry of Roots pump rotor based on Cassini oval principle was derived. The polar coordinate system used, and radius vector, direction which set by φ angle, characterizes location point rotor. distance this from axis rotation calculated value ρ_R vector. γ angle rotors their mutual orientation in plane rotation. Peculiarities choice a b parameters that satisfy shape are considered. An example is given R = 50 mm, rounding r 20 33.166 28. Rotor...

Mathematical model for designing the surface geometry of Roots pump rotor based on Cassini oval principle was derived. The polar coordinate system used, and radius vector, direction which set by φ angle, characterizes location point rotor. distance this from axis rotation calculated value ρ_R vector. γ angle rotors their mutual orientation in plane rotation. Peculiarities choice a b parameters that satisfy shape are considered. An example is given R = 50 mm, rounding r 20 33.166 28. Rotor...

The paper presents a theoretical analysis from an energetic and exergetic point of view for liquid air energy storage system (LAES). This identifies upper bounds on the efficiency this system. uses simple Linde-Hampson liquefaction cycle subsystem direct expansion method without heating above ambient temperature, power generation subsystem. It is known that as temperature decreases, destruction mechanical work input increases due to irreversibility working processes. As result, any...

Cryogenic energy storage (CES) is a large-scale technology that stores electricity in the form of liquefied gas at cryogenic temperatures. The CES system has three sub-processes, namely, charging or liquefaction, storage, discharging power cycle. Because main costs this are related to liquefaction module, we will focus on analysis processes. present work aims performing comparative study between cycles commonly used for air evaluate and compare their performance under given working...

The paper presents an exergy analysis of a heat pump with steam injection. Different refrigerants as R290, R152A and R1234yf are considered. Constructive schemes such two-stage pumps or cascade couplings known used to reduce the temperature at compressor discharge level, but presence two more compressors increases cost initial investment equipment. This design injection that has advantage simple construction can be applied in wide range. For each apparatus, corresponding its utility...