This paper presents a new composite phase change material made of paraffin and recycled aluminum sawing chips. Aluminum chips were selected as thermal conductivity enhancer, the volume fraction (~15%) which, in material, was minimized by selecting with shape that minimizes its packing density. Therefore, particles remained contact inside composite, thus, their sinking liquid state avoided. The obtained had latent heat capacity reduced 20% compared to increased 236%. materials also wide...

The study proposes a method for preliminary and estimative sizing of the main components solar district heating systems, with seasonal thermal storage. parameters determined by this method, are aperture area collectors volume proposed is only estimative, but it provides necessary input data investigation ofthe dynamic behavior such systems. advantage that requires very few accessible data. Two situations considered: first in which available climatic as annual global radiation on horizontal...

The study proves that high-temperature heat pumps with CO 2 of air to water type, in monobloc construction, can replace the gas boilers for heating and DHW, an industrial building. most efficient configuration is proposed 3 250 kW nominal thermal power capable provide 81 % annual energy electric 720 total produce remaining 19 energy. COP decreases if number increases. A single pump will achieve 2.66 without PV system while pumps, be 2.37 system. payback period 3.10 years 3.26

The study provides a complex analysis for replacement of the natural gas boilers with air to water heat pumps, as source hot be used in car washing machines. It was considered pumps R744 and R290 refrigerant, it proved that even seem undersized at negative temperatures, can still provide required 70 % full operating time. feasibility determined higher payback period is lower than 2 years average frequency less 5 cars washed / hour. storage tank increase continuous operation ambient...

The study presents a numerical investigation on operating conditions and performances of solar absorption chiller with LiBr-H2O. working cycle the investigated cooling equipment was modelled based thermodynamic principles by use software platform Engineering Equation Solver validated similar studies reported in literature. Further it influence like hot water temperature, temperature cold coefficient performance crystallisation. model proved to be capable describe behaviour evaluate safe from...

The study presents a complex evaluation of the indirect evaporation cooling technology potential to reduce energy consumption fresh air conditioning system, an office building in climatic conditions Cluj-Napoca, Romania. was realized for season one year based multiannual values ambient temperature and relative humidity. It considered two types systems. classic system composed battery powered by electric chiller evaporative recuperative heat exchanger, equipment same battery. found that...

In the context of complex worldwide energy crisis, solar district heating and embedded seasonal storage tanks can contribute to increase efficiency in systems. The analytical investigation thermal behavior allows evaluation reduction consumption, that be achieved, correct sizing both fields tanks. study presents complete models for fully mixed stratified tanks, integrated provided validation was realized by comparison with results available literature. Three five comparisons were conducted...

The paper presents a solar radiation monitoring system, using two scientificpyranometers and an on-line computer home-made data acquisition system. firstpyranometer measures the global other one, which is shaded,measure diffuse radiation. values of total arecontinuously stored into database on server. Original software was created for dataacquisition interrogation server application acquires datafrom pyranometers stores it with baud rate one record at 50seconds. client-server queries...

The study presents a global evaluation of the potential to use solar radiation in air conditioning with application an office building located Cluj-Napoca, Romania. was realized for one year period, based on multiannual average values and ambient temperature. It were compared performances two types cooling systems, absorption chiller photovoltaic type. is presented methodology calculation efficiency thermal field equivalent field, placed terrace roof building, considered completely filled...

The study presents a mathematical investigation on the potential to provide electricity of different solar Organic Rankine Cycle systems and photovoltaic system. As input data for all systems, were considered multiannual climatic Cluj-Napoca, Romania. field was in three configurations based flat collectors, evacuated tubes collectors parabolic trough collectors. modelled working fluids considering thermal regime typical each type It found that maximum electric power situated range (58.57 …...

The study presents a new analytical model capable to reveal the thermal behaviour of all components solar ammonia-water absorption system, powered by parabolic trough collectors, serving different types food storages: refrigeration chamber, refrigerated storage, freezing chamber and frozen storage. heat inputs, that determine total cooling load, for each storage spaces consist of: gains through walls, ventilation (fresh air), must be dissipated from stored products (technological load...

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...

The study presents a numerical analysis of the flow and heat transfer on latent storage device based phase change material (PCM) encapsulated in spherical shells. This kind system is designed for passive cooling air conditioning applications by cold accumulation through solidification PCM during night discharge melting day. taking into consideration both processes. geometry analysed was taken from an experiment available literature obtained results were compared with those experiment....

This study presents an investigation concerning the conversion of solar radiation into heat, cold, and electricity on facades virtual buildings located in four different cities that correspond to climatic conditions. Two are Eastern Europe, Romania, one city is situated Western Spain, western coast United States. Four active applications integrated were investigated: heating based flat collectors, cooling a LiBr-H2O absorption cycle, photovoltaic electricity, heat organic Rankine cycle. The...

Pollen viability and germination are very important in choosing pollinating varieties neededto ensure high quality yields. In this study, the of pollen from ten applecultivars growing density system (3174 trees/ha), climatic conditions Cluj-Napoca,Romania were investigated. vitro tests (hanging drop agar-plate) used toestimate these cultivars. The ofpollens varied significantly according to Among cultivars analyzed terms pollenviability best results recorded ‘Pinova’ (89.92%), ‘Gala’...

The study presents an experimental research carried out to the natural soil temperature variations and determine thermal diffusivity based solely on measurements. was conducted for two locations in Romania: Cluj-Napoca bare clay Reghin grass covered soil. It proved that design methodology of can be successfully applied any location. Based a statistical analysis data, simple precise mathematical model variation identified each An important particularity models is parameter are presented...