Energetic and Exergetic Analysis of Low Global Warming Potential Refrigerants as Substitutes for R410A in Ground Source Heat Pumps

Abstract

In the European Union (EU), buildings are responsible for about 40% of the total final energy consumption, and 36% of the European global CO2 emissions. The European Commission released directives to push for the enhancement of the buildings energy performance and identified, beside the retrofit of the current building stock, Heating, Ventilation, and Air Conditioning (HVAC) systems as the other main way to increase renewable energy sharing and overall building energy efficiency. For this purpose, Ground Source Heat Pumps (GSHPs) represent one of the most interesting technologies to provide energy for heating, cooling, and domestic water production in residential applications, ensuring a significant reduction (e.g., up to 44% compared with air-source heat pumps) of energy consumption and the corresponding emissions. At present, GSHPs mainly employ the refrigerant R410A as the working fluid, which has a Global Warming Potential (GWP) of 2087. However, following the EU Regulation No. 517/2014 on fluorinated greenhouse gases, this high GWP refrigerant will have to be substituted for residential applications in the next years. Thus, to increase the sustainability of GSHPs, it is necessary to identify short time alternative fluids with lower GWP, before finding medium-long term solutions characterized by very low GWP. This is one of the tasks of the UE project "Most Easy, Efficient, and Low-Cost Geothermal Systems for Retrofitting Civil and Historical Buildings" (acronym GEO4CIVHIC). Here, a thorough thermodynamic analysis, based on both energy and exergy analysis, will be presented to perform a comparison between different fluids as substitutes for R410A, considered as the benchmark for GSHP applications. These fluids have been selected considering their lower flammability with respect to hydrocarbons (mainly R290), that is one of the main concerns for the companies. A parametric analysis has been performed, for a reversible GSHP cycle, at various heat source and sink conditions, with the aim to identify the fluid giving the best energetic performance and to evaluate the distribution of the irreversibilities along the cycle. Considering all these factors, R454B turned out to be the most suitable fluid to use in a ground source heat pump, working at given conditions. Special attention has been paid to the compression phase and the heat transfer in evaporator and condenser.

Performance and Exergy Transfer Analysis of Heat Exchangers with Graphene Nanofluids in Seawater Source Marine Heat Pump System

“…The results can be used to optimize the refrigerant charge of the refrigeration unit and its components. Bobbo et al [17] analyzed different refrigerant fluids as alternatives to the ground source heat pump R410A. The thermodynamic properties, flow rate, pressure, and heat transfer efficiency of R32, R290, and R454b are compared in the system compressor, evaporator, and condenser under given conditions.…”

The Energy and Exergy of Light with Application to Societal Exergy Analysis

“…The second aspect is to note that modern lighting is provided via an energy conversion chain: primary energy carriers (e.g., coal) are converted to final energy (electricity, measured in watts, W) and lastly to useful energy (visible light, measured in lumens, lm). The field of exergy analysis has long analyzed individual machines and power plants in the energy conversion chain for their exergetic efficiency and performance, e.g., co-generation power plants [12], nuclear power plants [13], refrigerators [14], heat pumps [15], and energy storage systems [16]. In contrast, the field of societal exergy analysis evaluates entire energy conversion chains at regional, national, or world levels in exergy terms and considers light (and many other useful energy products) to be enablers of economic growth.…”

R134a'ya Alternatif Bir Soğutucu Akışkan (R513A) Kullanan Buhar Sıkıştırmalı Soğutma Sistemlerinin Enerji ve Çevresel Analizi

“…HFC'lerin yüksek GWP oranına sahip olması nedeniyle Avrupa Birliği 517/2014 yılında çıkarılan tüzük ile önümüzdeki 15 yılda pazarlanacak toplam miktarının önemli derecede azaltılması planlanmaktadır. Bu düzenleme ile ilk olarak 2015 yılından itibaren GWP oranı 150'nin üzerinde olan HFC'lerin ev tipi buzdolaplarında kullanılması yasaklanmıştır [2]. İklim değişikliğinin olumsuz sonuçlarını ortadan kaldırmak için yapılan bu düzenlemeler HFC soğutucu akışkanların fiyatlarını arttırdı.…”

“…1990'lı yıllardan beri gelişmiş ülkelerde kullanılan soğutma sistemlerinde yüksek küresel ısınma potansiyeline sahip soğutucu akışkanlar kullanılmaktadır. Bu soğutucu akışanların sızıntı yoluyla atmosfere salınması nedeniyle iklim değişikliği üzerinde etkisi büyüktür [1][2].…”