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CPOTE2020 logo
6th International Conference on
Contemporary Problems of Thermal Engineering
Online | 21-24 September 2020

Abstract CPOTE2020-1209-A

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An efficient cooling system for marine applications using low GWP refrigerants

Jan WAJS, Gdansk University of Technology, Poland
Michał MRÓZEK, Gdansk University of Technology, Poland
Dariusz MIKIELEWICZ, Gdansk University of Technology, Poland

Due to a perceived negative human impact on the climate change there is a growing pressure on the withdrawal of refrigerants featuring high global warming potential (GWP). European Union (EU) regulations for land-based refrigeration and air conditioning equipment already limit the GWP of refrigerants to a maximum value of 150. This type of regulation has stimulated HVACR industry to consider natural refrigerants, hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs). It is anticipated that imposed constraints and a phase-out of popular HFC refrigerants with the high GWP will significantly affect market prices and lead marine industries to search for alternative solutions. In addition, HVACR installations on ships are required to use feasibly simple and trouble-free technologies, and to use non-flammable and non-toxic refrigerants (safety class A1 according to ASHRAE standard). This paper presents the concept of a cold supply system dedicated for ships in which the refrigeration plant uses carbon dioxide as a working fluid and heat is dropped to ice water produced in a chiller using R1233zd(E) as a refrigerant. The analysed refrigeration plant employs a two-stage compression booster configuration, that is the most popular solution used with carbon dioxide. A single-stage compression with an internal heat exchanger configuration was used to produce the ice water in the air conditioning system. Results of the proposed system’s energy analysis were compared with the classic refrigeration and air conditioning system implemented on ships as two independent units, assuming carbon dioxide as a refrigerant fluid for both units and seawater as a coolant of the gas cooler/condenser. In each considered case, the energy efficiency was determined depending on the seawater temperature. An additional analysis was conducted to measure the impact of replacing the booster system by a simpler single-stage circuit with the temperature in the cold store controlled by a throttle valve. The conducted comparative analysis shows the desirability of using the proposed system to improve energy efficiency and to reduce the cost of refrigeration and air conditioning plants. An additional benefit of the considered project lies in its positive environmental impact.

Keywords: Marine refrigeration, Low GWP refrigerants, Carbon dioxide, Energy analysis, Efficiency
Acknowledgment: The results presented in this paper were obtained from research work co-financed by the National Centre of Research and Development in the framework of Contract POIR.01.02.00-00-0009/18 – INNOship Programme – The development of an innovative, ecological refrigeration appliance designed to be applied in ships and vessels.