Ceramic tile production is an industrial process where energy efficiency management is crucial, given the high amount of energy (electrical and thermal) required by the production cycle. This study presents the preliminary results of a research project aimed at defining the benefits of using combined heat and power (CHP) systems in the ceramic sector. Data collected from ten CHP installations allowed us to outline the average characteristics of prime movers, and to quantify the contribution of CHP thermal energy supporting the dryer process. The electric size of the installed CHP units resulted in being between 3.4 MW and 4.9 MW, with an average value of 4 MW. Data revealed that when the goal is to maximize the generation of electricity for self-consumption, internal combustion engines are the preferred choice due to higher conversion efficiency. In contrast, gas turbines allowed us to minimize the consumption of natural gas input to the spray dryer. Indeed, the fraction of the dryer thermal demand (between 600–950 kcal/kgH₂O), covered by CHP discharged heat, is strictly dependent on the type of prime mover installed: lower values, in the range of 30–45%, are characteristic of combustion engines, whereas the use of gas turbines can contribute up to 77% of the process’s total consumption.

Ceramic tile manufacturing is a highly energy-intensive process. Concerns about carbon emissions and energy costs make energy management crucial for this sector, which holds a leading role in Italian industry. The paper discusses the energetic and environmental performance of cogeneration (CHP) in the ceramic industry, where prime mover exhaust heat is supplied to a spray-dryer system, contributing to the satisfaction of the thermal demand and decreasing natural gas consumption. A thermodynamic model of a dryer unit, validated against real data, has been set-up to provide a detailed representation of the thermal fluxes involved in the process. Then, the thermal integration with two types of CHP prime movers of similar electric size (4 MW) is investigated. Energetic results show that the gas turbine can contribute up to 81% of dryer thermal consumption, whilst internal combustion engine contribution is limited to 26%. A methodology was ad-hoc defined for the environmental assessment of CHP, accounting for global (CO₂) and local (CO and NO_X) emissions. Results confirm that CHP units guarantee reduction of CO₂ and NO_X compared to separate generation, with maximum values equal to 81 g/kWh_th and 173 mg/kWh_th, respectively; CO emission is decreased only in the case of gas turbine operation, with savings equal to 185 mg/kWh_th.

The liquefied natural gas (LNG) is considered a viable solution to replace oil-based engines (common in heavy-duty truck and naval industry) reducing the environmental impact in the transport sector. Since liquefaction plants represent energy intensive processes, the best configurations/operation assessment is of primary importance. In this paper, a novel general procedure for the thermodynamic design and optimization, engineering design and off-design evaluation for small-scale LNG production systems is presented. The procedure can be used for the complete design and performance evaluation of plug & play facilities at filling stations for vehicles/boats, with the contemporary benefits of reducing pollutant emission in the city/port area and operating as electrical storage, coupled with renewable generators. Furthermore, the procedure has been applied to a case study (ferry boat operating at the main canal in the port of Ravenna, Italy), evaluating the optimal size for the integrated wind plant by minimizing the electricity introduction into the grid. The obtained results show 78 kW as optimal wind size, allowing the LNG plant to operate 187 h/year in design and 4720 h/year in off-design conditions, with electricity surplus around 33 MWh/year. A prototype will be installed to reduce pollutant emissions and test this technology as a storage option for renewable sources.

In this paper, we present an experimental assessment of the performance of a partial evaporating organic Rankine cycle (PE-ORC) power system. The system converts low temperature heat into electrical energy, with a power size around 1 kW, thus suitable for micro-generation in the residential sector. Although the test bench was designed for operating with superheated vapour at the expander inlet, it has demonstrated to be able to work with the expansion occurring entirely in two-phase condition. Since the direct measurement of the vapour quality is not possible using the sensors installed in the test rig, the state of the fluid in the two-phase condition is estimated by means of the thermal balance at the heat exchangers, so the thermodynamic cycle can be evaluated. Temperatures of the heat source in the range between 40 °C and 75 °C have been tested, and for each temperature value the vapour quality at the expander inlet has been varied by regulating the feed-pump rotating speed. Experimental data are provided regarding the performance of the overall cycle, of the heat exchangers, of the expander and of the feed-pump. It was observed that the effectiveness of the evaporator and the efficiency of the pump are improved with respect to the operation with superheated vapour at the expander inlet. However, the overall performance is lower, especially due to the high ratio of the pump consumption over the expander produced power, commonly called back work ratio (BWR). The latter, under some boundary conditions, has resulted higher than the unit, meaning that the system is not able to produce net electrical power. The aim of the paper is to identify the design characteristics required by a micro-ORC energy system in order to enhance its performance in the PE operating mode.

Brazed-plate heat exchangers (BPHEs) are widely used as recuperators in organic Rankine cycle (ORC) systems, but their corrugated passages make full-scale Computational Fluid Dynamics (CFD) simulations prohibitively expensive, limiting the use of CFD for performance prediction and for deriving design-oriented heat-transfer correlations. This work presents a validated domain-reduced CFD methodology for a BPHE recuperator operating with R134a. The computational domain is reduced to a single exchange unit (one vapor and one liquid corrugated channel separated by one heat-transfer plate), further downscaled by truncating the plate length to the fully developed corrugated region, exploiting longitudinal symmetry, and approximating the corrugation profile with a trapezoidal shape; the resulting mesh (≈4.5 × 10⁶ cells) is approximately 44.5 times smaller than the estimated 2 × 10⁸-cell full-stack mesh. Five steady operating points from a micro-scale ORC test rig (mass-flow rate 0.08–0.22 kg/s, Re ≈ 500–18,500) are used for validation by mapping experimental data to the reduced domain through an ε–NTU formulation. CFD predictions of hot- and cold-side temperature changes agree within 1–10% of the reference values. Building on this validated model, single-phase Nusselt-number correlations are proposed, valid over 500 < Re < 1400 for the liquid phase and 6000 < Re < 18,500 for the vapor phase. The proposed method and results support preliminary, geometry- and model-specific assessment of BPHE recuperators; broader transferability requires additional geometries, operating points and model-form validation.