Studio di sistemi per la produzione di freddo a bordo di imbarcazioni impieganti macchine frigorifere ad assorbimento alimentate da cascami termici di motori a combustione interna

Responsabili di progetto

Andrea Frazzica, Robert Ghirlando

Accordo

MALTA - UM-exipred - University of Malta

Bando

CNR/UoM biennio 2018-2019 2018-2019

Dipartimento

Ingegneria, ICT e tecnologie per l'energia e i trasporti

Area tematica

Ingegneria, ICT e tecnologie per l'energia e i trasporti

Stato del progetto

Nuovo

Proposta di ricerca

The survey performed by the International Marine Organization [1] shows that in 2012 the international maritime fleet caused the emission of about 900 million tons of CO2. The same study reported an outlook up to 2050, predicting a further and continuous increase of the Greenhouse Gases (GHG) emissions. Particularly, about 10000 tons of emissions are related to refrigerant losses. Despite the introduction of novel refrigerants, characterized by lower Global Warming Potential (GWP), the ones that are still commonly employed are characterized by GWP values higher than 1000. Furthermore, the on-board air conditioning and refrigeration systems cause additional primary energy consumptions for driving the compressors of the vapour compression machines. It has been estimated that the additional gaseous emissions related to the operation of these machines account for 25% of the overall emissions [2].
According to the above reported analysis, it is clear that a better utilization of on-board energy sources is of primary importance in order to optimize the energy efficiency, thus reducing GHG emissions and operational costs. One of the most effective ways to increase the energy efficiency is represented by the recovery of thermal energy wasted off by the internal combustion engine (ICE) through the coolant loop. Indeed, it has been reported [3] that more than 30% of waste heat in the ICE coolant loop can be recovered at temperature levels up to 180°C. The thermal energy recovered can then be used to drive a small scale ORC [4], to provide space heating [5] and on-board water desalination [3]. Several scientific publications focused on the exploitation of wasted thermal energy to drive a sorption chiller, providing heating and cooling energy [6].
An interesting topic of investigation is represented by the possibility of producing refrigeration energy out of the wasted thermal energy from ICE for fishing vessels, to preserve the fish during daily operation, by employing thermally driven vapour sorption machines to produce refrigeration. This way, the fuel consumption and the related GHG emissions can be reduced. Moreover, sorption machines employ non-polluting refrigerants (e.g. ammonia, water, alcohols) which can further limit the GHG emissions. This is a critical topic for countries like Italy and Malta, where the fishing activity in the Mediterranean Sea represents an important business. In the last years, both CNR ITAE and UM started working on the energy optimization of fishing vessels. The possibility to initiate a joint collaboration in the framework of a bilateral agreement can open further options to strengthen and deepen this application.
The present project will aim at a theoretical and experimental analysis of the possible integration of sorption refrigeration systems with ICE for fishing preservation on-board. The activity will be organized as follows:
- State of the art analysis of refrigeration systems commonly installed on-board of fishing vessels and innovations introduced to increase the energy efficiency. Analysis of typical refrigeration loads, primary energy consumptions and ICE waste heat available, in terms of power and temperature level. Investigation of possible waste heat recovery schemes and integration with sorption refrigeration technologies. Expected outcome of this activity is represented by the publication of a review on an international journal.
- Development and implementation of a flexible numerical simulation model for the energy system simulation. The model will be implemented in a commercial software (e.g. TRNSYS, Esp-R, Matlab/Simulink) and will be able to simulate different sorption machine technologies (e.g. absorption, adsorption), different load profiles and control logics. Particularly, sorption machine performance maps will be extracted either from literature or from experimental tests at the CNR ITAE laboratories, while the load profiles will be obtained from literature. The implemented model will be then employed to perform sensitivity analysis of the system configurations, in order to highlight the main parameters affecting the system performance. In order to make an objective assessment, some main Key Performance Indicators (KPIs), such as primary energy efficiency, CO2 saved emissions, operational cost savings, will be defined and employed to comparatively evaluate the different simulated schemes.
- Experimental testing of two sorption technologies at the CNR ITAE laboratories. An already existing testing rig, installed at the CNR ITAE and connected to a climatic chamber, will be then employed to measure the system performance. The analysis will be performed by varying the boundary conditions, focusing on the effect of the refrigeration load. Both an ammonia-water commercial absorption machine and an ethanol-activated carbon adsorption prototype will be comparatively tested. The obtained results will be then employed to validate the simulation model. We envisage to publish at least two more papers focusing on modelling and experimental activity.
- Possible follow up of this bilateral agreement will be represented by the preparation of joint EU proposals in the field of energy efficiency.

[1] Third IMO GHG study. International Maritime Organization; 2014
[2] Schwarz W, Rhiemeier J-M. The analysis of the emissions of fluorinated greenhouse gases from refrigeration and air conditioning equipment used in the transport sector other than road transport and options for reducing these emissions Maritime, Rail, and Aircraft Sector, a final report. EU; November 2007
[3] Shu G, Liang Y, Wei H, Tian H, Zhao J, Liu L. Renew Sustain Energy Rev 2013;19: 385-401
[4] Choi In-Hwan, Lee Sangick, Seo Yutaek, Chang Daejun.. Energy 2013;61: 179-95
[5] Bidini G, Maria F, Generosi M. Appl Therm Eng 2005;25: 851-65
[6] Cao T, Lee H, Hwang Y, Radermacher R, Chun HH. Appl Therm Eng 2015;90: 820-30

Obiettivi della ricerca

Main objectives of the joint collaboration will be the following:
- Investigation of the current state of the art of refrigeration systems for fishing vessels application, focusing on energy efficiency;
- Definition of system schemes for the ICE waste heat recovery integrated with thermally driven sorption refrigerators for fishing vessels applications;
- Implementation of a numerical lumped parameter model, able to integrate different sorption machine technologies, refrigeration loads and control strategies;
- Definition of KPIs for the evaluation of energy efficiency, pollutant savings and operational costs of the simulated systems;
- Parametric analysis of the achievable performance of different simulated system layouts;
- Experimental characterization of an absorption refrigerator and an adsorption refrigerator under typical boundary conditions. The experiments will be performed by means of an already existing test rig at the CNR ITAE laboratories;
- Validation of the simulation model through the experimental data;
- Publication of at least three papers in international journals;
- Strengthening of the collaboration between UM and CNR ITAE, in view of possible future proposals submission.

Ultimo aggiornamento: 19/09/2024