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Radiators represent the most spread heating body (installed since late 1800s) and in the last decades different radiators typologies have been proposed on the market, characterized by different materials, sizes, shapes, etc. Recent EU Directive on energy efficiency has set the obligation to install individual meters for space heating in building served by a central heating source. To this aim, when direct heat meters are not technically feasible, indirect systems like heat cost allocators are applied on each radiator in a dwelling and the knowledge of single radiators’ thermal output is essential for an accurate and fair heat cost sharing. The EN 442:2014 describes a method for radiators’ thermal output measurement whose expanded uncertainty is lower than 1% in reference laboratory conditions. However, radiators’ thermal output is strongly dependent on installation and boundary conditions. Thus, to get radiators’ thermal output at operating conditions “characteristic equations” are available but, unfortunately, they do not include any possible actual operating condition among which: installation position with respect to the wall and the floor, presence of grid/shelf/niche or an obstruction (e. g. caused by curtains), thermo-fluid-dynamic condition variations (inlet flow rate and temperature), and hydraulic connections. In this paper, the experimental results of thermal output measurement of different radiators typologies (cast iron, aluminum) at different installation conditions are presented, together with an analysis of the associate technical-economic effects on space heating cost sharing. Reductions of radiators’ thermal output up to 15% due to hydraulic connections and between 10% and 20% due to flow-rate variations have been found. Furthermore, different installation conditions showed deviations between operating and standard radiators’ thermal output between 5% and 15%.

To reduce greenhouse gas emissions, internationally research and development is intended to improve the performance of conventional refrigeration system also growth of new-fangled refrigeration technology of potentially much lesser ecological impact. This paper gives brief review of research and development in thermoacoustic refrigeration also the existing situation of thermoacoustic refrigeration system. Thermoacoustic refrigerator is a novel sort of energy conversion equipment which converts acoustic power into heat energy by thermo acoustic effect. Thermoacoustic refrigeration is an emergent refrigeration technology in which there are no moving elements or any environmentally injurious refrigerants during its working. The concept of thermoacoustic refrigeration system is explained, the growth of thermoacoustic refrigeration, various investigations into thermoacoustic refrigeration system, various optimization techniques to improve COP, different stacks & resonator tube designs to improve heat transfer rate, various gases and other parameters like sound generation have been reviewed.

The present paper aims at analysing the performances of Organic Rankine Cycles (ORCs) adopted for the exploitation of the biomass resulting from the pruning residues in a 3000 hectares district in Southern Italy. A parametric energy analysis has been carried out to define the influence of the main plant operating conditions. To this purpose, both subcritical and transcritical power plants have been examined and saturated and superheated conditions at the turbine inlet have been imposed. Moreover, the effect of the working fluid, condensation temperature, and internal regeneration on system performances has been investigated. The results show that ORC plants represent an interesting and sustainable solution for decentralised and small-scale power production. Furthermore, the analysis highlights the significant impact of the maximum temperature and the noticeable effect of internal regeneration on the performances of the biomass power plants.

The mathematical model will be able to predict the operated condition (required tube diameters, heat input and submergence ratio?.). That will result in a successful bubble pump design and hence a refrigeration unit. In the present work a one-dimensional two-fluid model of boiling mixing ammonia-water under constant heat flux is developed. The present model is used to predict the outlet liquid and vapor velocities and pumping ratio for different heat flux input to pump. The influence of operated conditions such as: ammonia fraction in inlet solution and tube diameter on the functioning of the bubble pump is presented and discussed. It was found that, the liquid velocity and pumping ratio increase with increasing heat flux, and then it decreases. Optimal heat flux depends namely on tube diameter variations. Vapour velocity increases linearly with increasing heat flux under designed conditions.