Conventional Air Conditioning System Research Articles

Thermodynamic performance assessment of a solar-driven desiccant evaporative air cooling system (SDEAC) for outdoor environments- a dynamic study

In this work, a novel dynamic model of a solar-driven desiccant evaporative air cooling system for outdoor environments is proposed, namely the SDEAC system. The effects of operating and designing parameters on the performance of the SDEAC system are analyzed. The results indicate that the sensible cooling capacity, the latent cooling capacity, and the COP decrease monotonically as the rotational speed of the desiccant wheel increases. When the ratio of dehumidification area to total area (r1) is 0.5, the performance of the SDEAC system is optimal under the condition of sufficient solar radiation. The ratio of the dehumidified air flowrate to the regenerated air flowrate has a small effect on the cooling capacity but has a large effect on the COP. The SDEAC system has a higher sensible cooling capacity and total cooling capacity compared to the EAC system. Moreover, although the COP of the SDEAC is lower than that of the EAC system, it is still maintained at a relatively high level. The SDEAC system with a supply air flowrate of 670 m3/h to cool the outdoor air saves about 1283∼1617 kWh of electricity and 788 kg–1139 kg of carbon emission reduction compared to a conventional vapor compression air conditioning system in different cities during the period of June to August.

Evaluation of energy performance and environmental benefits for transcritical CO2 thermal system in high-speed trains

The conventional air conditioning system used in high-speed railways has limitations in heating performance and environmental impact, necessitating the exploration of alternative refrigerants. The transcritical CO2 system has gained popularity due to its exceptional heating efficiency and environmental benefits. This study aims to evaluate the energy and environmental potentials for transcritical CO2 systems in high-speed trains based on four-vertical-and-four-horizontal railway lines within different climatic regions of China. A high-fidelity transcritical CO2 system model was first developed and validated through experiments. Then, a comprehensive energy and environmental evaluation method was proposed and applied to the four-vertical-and-four-horizontal railway lines. The results indicated that the transcritical CO2 system had a superior heating performance and competitive cooling performance based on daily and annual operations. Furthermore, the transcritical CO2 system exhibited significant environmental advantages with lower total life cycle climate performance for all lines, with an average emissions reduction ratio of 17.6% and a maximum emissions reduction ratio of 26.98%. These findings highlight the competitive energy performance and outstanding environmental benefits offered by transcritical CO2 systems as promising alternatives to air conditioning systems in railway transportation.

Energy Geo-structures: a review of their integration with other sources and its limitations

Ground Source Heat Pumps, in the framework of Shallow Geothermal Energy Systems, outperform conventional Heating Ventilation and Air Conditioning systems, even the high efficiency Air Source Heat Pumps. At the same time, though, they require considerably higher installation costs. The utilization of dwellings' foundations as ground heat exchanger components has recently demonstrated the potential to generate significant cost reductions primarily attributed to the reduction in expenses associated with drilling and backfill material (grout). These elements are referred to in the literature as Thermo-Active Structures or Energy Geo-structures (EGs). The current study employs a ‘mixed studies’ review (i.e., literature review, critical review and state-of-the-art review) methodology to comprehensively examine and assess the compatibility and integration of different renewable energy sources and environmentally friendly technologies with foundation elements deployed as EGs. These mainly include heat pumps, district heating and cooling networks, solar-thermal systems, waste heat, biomass and other types such as urban structures. Emphasis has been given on the advancement on this area, with the current study identifying and addressing two primary categories. The first category involves the integration of EG elements with sources that are able to supply green electricity, referring to renewable energy electricity obtained from on-grid or off-grid integration. The second category, involves a direct or indirect integration with sources that provide heat, or vice versa. The technical and non-technical barriers of such integrations have been discussed in detail, with the technical challenges generally involving engineering design, and system optimization, whereas non-technical challenges encompassing the economic, social, and policy domains.

Design optimization of the cooling systems with PCM-to-air heat exchanger for the energy saving of the residential buildings

Driven by a rapid surge in cooling demand in buildings, the energy consumption dedicated to cooling has experienced remarkable growth. To address this challenge, the adoption of latent heat thermal energy storage utilizing phase change materials (PCM) has gained significant momentum in recent years. This paper presents the design and evaluation of an integrated latent heat thermal energy storage (ILHTES) system tailored for residential buildings. This system integrates a PCM-to-air heat exchanger (PAHX) with an air conditioning unit. Modelica language is utilized to develop a numerical model for the ILHTES system. The heat transfer model of the PAHX is developed and validated using existing literature data. To simulate the dynamic behavior and energy consumption of the residential building, the open-source library AixLib is adopted. The developed ILHTES system model is used for the optimization of key design variables, including the PCM slab thickness and air flow rate, based on the results of long-term simulations covering the entire cooling season. Evaluation of the energy saving potential of the optimized ILHTES systems is carried out in comparison to conventional air conditioning systems, considering various climatic conditions in five European cities. The results highlight the profound impact of PCM types on the Energy Saving Ratio (ESR) throughout the entire cooling season. Among the four commercially available PCMs examined—RT27, RT25, RT20, and RT18—RT25 consistently outperforms the others. Across all five cities investigated, using RT25 leads to a minimum ESR of 16% in Catania and a maximum ESR of 44.7% in Stockholm for the entire cooling season.

Geothermal Heat Pump for Space Cooling and Heating in Kuwaiti Climate

Kuwait stands as one of the hottest locations globally, experiencing scorching temperatures that can soar to 50 °C during the summer months. Conversely, in the winter months of December and January, temperatures may plummet to less than 10 °C. Maintaining a comfortable temperature indoors necessitates a substantial amount of energy, particularly during the scorching summer seasons. In Kuwait, most of the electrical energy required for functions such as air conditioning and lighting is derived from fossil fuel resources, contributing to escalating air pollution and global warming. To reduce dependence on conventional energy sources for heating and cooling, this article presents a case study to explore the potential of using geothermal energy for space heating and cooling in Kuwait. The case study involves utilizing a geothermal heat pump (water-sourced heat pump) in conjunction with a vertical-borehole ground heat exchanger (VBGHE). The mentioned system is deployed to regulate the climate in a six-floor apartment block comprising a small two-bedroom apartment on each level, each with a total floor area of 57 m2. Two geothermal heat pumps, each with a cooling capacity of 2.58 kW and a heating capacity of 2.90 kW, connected to two vertical-borehole heat exchangers, were deployed for each apartment to maintain temperatures at 22 °C in winter and 26 °C in summer. The findings indicate that the estimated annual energy loads for cooling and heating for the apartment block are 42,758 kWh and 113 kWh, respectively. The corresponding electrical energy consumption amounted to 9294 kWh for space cooling and 113 kWh for space heating. The observed peak cooling load was approximately 9300 kJ/h (2.58 kW) per apartment, resulting in a power density of 45 W/m2. Moreover, the HP system achieved a 22% reduction in annual electric energy consumption compared to conventional air conditioning systems. This reduction in electric energy usage led to an annual CO2 reduction of 6.6 kg/m2.

An experimental investigation on the novel hybrid indirect direct evaporative cooling system

The Evaporative Cooling Technology has revived in the past few decades owing to the gradual shift of economies towards investing in sustainable cooling systems which has led to many governments defining sustainability targets in reducing GHG emissions and achieving climate neutrality with many EU countries aiming to reach net zero emissions by 2050. The major contribution towards GHGs are the conventional air conditioning systems which incorporate energy intensive compressor units and refrigerants as working fluids. A great deal of research has been done on the Evaporative Cooling Technology particularly, the DEC – Direct Evaporative Cooling systems due to their cost-effectiveness, design simplicity and feasibility. The present study proposes a HIDEC – Hybrid Indirect Direct Evaporative Cooling System as an alternative to the conventional vapor compression systems which is unique considering its compact and two in one design incorporating both Indirect and Direct Cooling Channels in a single system. The HIDEC Experimental System is developed passing through the stages of fabrication and design, followed by realtime testing in the hot and humid, and hot and dry sub tropical climatic conditions of Islamabad. The HIDEC Experimental System when operated in Dual Hybrid Mode provides a substantial supply air temperature drop to 24.8 °C with a maximum achievable COP of 35.2 and Cooling Capacity of 16.8 kW. The overall wet bulb effectiveness of the system elevates to 85%, whereas the dew point effectiveness reaches a maximum of 80%.

Optimization of solar and heat pump complementary powered desiccant air conditioning system

The effective utilization of renewable heat sources is critical for energy saving in desiccant air conditioning systems. A new solar and heat pump complementary powered desiccant air conditioning system is proposed. The system consists of a solar and water source heat pump complementary reheat subsystem, a two-stage desiccant wheel, a three-stage air cooler, and a two-stage heat pipe exchanger. Simulation are performed in the transient simulation software TRNSYS, and the particle swarm optimization and the Hooke Jeeves algorithm with life cycle cost as the objective function are applied to optimize the collector area, the heat storage tank volume and the water-source heat pump power. The results show that the monthly average coefficient of performance of the system is 5.1, 5.6, 5.5 and 4.8 in June, July, August and September, respectively. Compared to the conventional air conditioning system, the new system has a 58.4% reduction in operation cost and a payback period of 6.6 years. The CO2 emission reduction rate of the new system can reach 65.2% in July and 65.1% in August, while it is the lowest in September at 62.9%. Based on the above, the new system has better energy efficiency, economic and environmental benefits.

Thermodynamic Performance Assessment of Air Conditioner Combining Evaporative and Passive Cooling

Abstract The global increase in refrigeration and air conditioning applications poses a severe problem as regards the environmental degradation caused by greenhouse gas emissions. This study introduces a novel approach wherein both evaporative cooling and passive cooling are integrated to unveil notable enhancements in energy and exergy compared to conventional air conditioning systems. Therefore, this work aims to enhance the thermal performance of a 1.5-ton split air conditioner (SAC) employing outdoor (condenser) evaporative and indoor passive cooling (EPC). The heat removal capacity of a condenser and SAC performance are greatly affected by the air temperature at the condenser inlet. Evaporative cooling serves to lower outdoor air temperature, while passive cooling minimizes the indoor cooling load. Design parameters encompass outdoor temperature (Ta = 30–44 °C), relative humidity (RH = 20–80%), and temperature reduction due to passive cooling (ΔTR = 0.5–5 °C). A model is developed to calculate the temperature reductions of outdoor air through evaporative cooling in diverse climatic conditions, while the range of passive cooling degrees is obtained from previous experiments. Results indicate a substantial enhancement in the thermodynamic performance of the proposed system. The maximum coefficient of performance (COP) improvement of 68.66% is achieved at 44 °C outside temperature and 20% relative humidity. Annual energy savings, under extreme operating conditions, range from 358.4 kWh to 2116.8 kWh. The EPC SAC is identified as more sustainable than the conventional split air conditioner (CSAC). Moreover, the projected system is anticipated to recoup its costs within a relatively short period of 1.42 years.

A novel compressor-ejector operating heat pump (CEO-HP) for separate sensible and latent cooling air-conditioning system

Decarbonization and electrification require advancing air source heat pumps for space cooling. Conventional air conditioning systems have a cooling coil and a reheater, which simultaneously handle the latent and sensible loads. This approach results in low energy efficiency, particularly for spaces with small sensible heat ratios where supply air should be reheated. Among several developed systems, separate sensible and latent cooling technology has been proposed to solve these issues by decoupling the latent and sensible loads. The present work proposes novel SSLC systems in which a compressor-ejector operating heat pump with two evaporators dissociates sensible and latent load. Moreover, two psychrometric air treatment arrangements are proposed and evaluated. A thermodynamic model is developed for the proposed compressor-ejector operating heat pump and air treatment arrangements to evaluate the energy efficiency of the proposed separate sensible and latent cooling systems compared to the conventional air conditioning system under the same operating conditions. Results indicate that the proposed separate sensible and latent cooling systems outperform the conventional system in terms of coefficient of performance when the room sensible heat ratio is less than 0.74. A 72% improvement in the coefficient of performance is estimated when the room sensible heat ratio is 0.6. Therefore, the proposed separate sensible and latent cooling systems would bring a significant reduction in operating costs, making them a good alternative to the conventional air conditioning system.

Thermal performance investigation of membrane-assisted radiant cooling system for localised outdoor cooling hub

Heat waves pose increasing threats to human well-being, especially in urban areas, and staying safe beyond comfort during heat waves is a crucial issue. Localised cooling hubs may provide thermal stress relief in the outdoor environment. For outdoor cooling applications, conventional air conditioning systems are not effective but energy-intensive, and the membrane-assisted radiant cooling system can be a potential alternative, which directly treats the radiant loads while minimising the convective heat loss to the ambient. In the present study, a numerical model is developed to analyse the heat transfer behavior of membrane-assisted radiant cooling for outdoor applications, considering the effect of solar and long-wave radiation and wind parameters. As the transmissivity of the membrane material plays a crucial role in reducing the amount of solar heat, the performances of three types of membranes, i.e., non-selective, mid-infrared selective, and sky-window selective, were compared and analysed at different times on a typical summer day in Hong Kong. The results indicate that the sky-window selective membrane, which allows only transmission of infrared in the 8–15 µm wavelength range, saves energy up to 44 % and 47% compared with mid-infrared selective and non-selective membranes, respectively. In the outdoor application, the equivalent convective heat transfer coefficient of the cooling panel can be reduced in the range of 2.2 W/m2K to 2.6 W/m2K. It is observed that, when the panel is not exposed to direct solar radiation, there is no advantage in using the mid-infrared selective membrane over the non-selective membrane. However, under direct solar radiation, a non-selective membrane-assisted cooling panel demonstrates poor performance, absorbing solar heat flux 2.27 times higher compared to MIR-selective membrane-assisted panel.

Exploring global accessibility of deep ocean water for sea water air conditioning (SWAC) process: Identifying feasibility areas depending on temperature source

Sea Water Air Conditioning (SWAC) technology is a highly efficient alternative to conventional air conditioning system using renewable marine energy to provide cooling to buildings. However, its implementation requires access to Deep Ocean Water (DOW) at 4–5 °C, thus SWAC is only viable in coastal regions. Furthermore, one of the major obstacles to its global development is the investment cost that remains high. This cost is strongly linked to the bathymetry of the installation location as it determines the length of the drawing pipeline, which accounts for the largest share of the investment cost. Knowing the temperature and bathymetry profiles will enable the establishment of the financial viability of SWAC technology in a specific location. This paper presents an analysis identifying areas of feasibility on a worldwide scale for standard SWAC implementation first. Then, it explores an alternative design with a higher drawing point for seawater at 12 °C (coupled with a High Temperature District Cooling), which reduces the cost by shortening the drawing pipeline and allows for more locations to be suitable for this technology. Additionally, the impact of the El Niño/Southern Oscillation (ENSO) is also considered since a shallower drawing point makes it more sensitive to temperature variations.

Using Latent Heat Storage for Improving Battery Electric Vehicle Thermal Management System Efficiency

<div>One of the key problems of battery electric vehicles is the risk of severe range reduction in winter conditions. Technologies such as heat pump systems can help to mitigate such effects, but finding adequate heat sources for the heat pump sometimes can be a problem, too. In cold ambient conditions below −10°C and for a cold-soaked vehicle this can become a limiting factor. Storing waste heat or excess cold when it is generated and releasing it to the vehicle thermal management system later can reduce peak thermal requirements to more manageable average levels. In related architectures it is not always necessary to replace existing electric heaters or conventional air-conditioning systems. Sometimes it is more efficient to keep them and support them, instead. Accordingly, we show, how latent heat storage can be used to increase the efficiency of existing, well-established heating and cooling technologies without replacing them. We investigate different possibilities for the integration of phase change materials into a baseline battery electric vehicle thermal management system and compare the resulting benefits.</div>

Experimental Investigation of Energy-Saving Potential of Ground Source Heat Pump During Peak Hour Operations

Abstract Ground-source heat pump (GSHP) systems have emerged as energy-efficient alternate systems for the conventional Air-Source Air-Conditioning (ASAC) systems for space heating and cooling applications. GSHPs have gained widespread popularity globally and are extensively utilized in residential and commercial buildings. However, in countries like India where both space cooling and heating are required, it becomes essential to evaluate the performance of the GSHP system, especially during peak-hour operation to estimate peak load energy demand. This research paper tries to identify the energy efficiency of the GSHP system during peak-hour operations in comparison to the ASAC system using experimental techniques. Experimental trials were conducted in a laboratory equipped with a single unit of 17.58 kW cooling/heating capacity GSHP system and a 17.57 kW cooling/heating ASAC system (two units of 7.023 kW and 10.548 kW). Experimental trials were conducted in peak summer in the month of June for cooling mode operation and January for heating mode operation for Roorkee weather conditions in the northern part of India. The performance of both systems was compared by defining instantaneous coefficient of performance (COP) and cyclic COP. The instantaneous COP was found to be higher for both the systems during peak-hour cooling and heating mode operations. Energy-saving analysis indicates that the ground-source heat pump system saves 36.85% and 38.65% of electrical energy in cooling and heating modes, respectively, compared to the ASAC system.

Cooling Potential Evaluation of a Ground Heat Exchanger in a Tropical Climate: A Case Study of an Office Building

The main implications of the hot-humid climate characteristics stipulate the need for cooling indoor environments. Ground thermal characteristics can be exploited in the search for sustainable ways to cool the indoor environment. Thus, this work aims to assess the cooling potential of the ground thermal characteristics through a vertical ground heat exchanger (VGHE) in a tropical climate such as Panama City via dynamic simulation. This potential is evaluated in a two-stories office building complying with Panama’s building regulation requirements, where a VGHE system is designed to cover the cooling needs. Since underground temperature data are unavailable, parametric and sensitivity analyses are carried out. For sizing the VGHE, a vertical ground system is chosen since this allows a better configuration in the installation for a building with large cooling demands and eliminates the need for large amounts of land. A difference of 33.52% (4481.4 kWh) in the electricity consumption for cooling was obtained compared to a conventional air conditioning system, which translates into a 770.80$ saving (0.172$/kWh). These results confirm that the system studied for air conditioning is feasible since it could provide positive results in thermal comfort and energy savings for the user.

Experimental and Hybrid Numerical Analytical Approach of an Earth-to-Air Heat Exchanger

Abstract The primary goal of this paper is to assess the thermal behaviour of Earth-to-Air Heat Exchanger (EAHE) under continuous operation mode during the cooling period in warm climatic conditions. An experimental setup was conducted in Biskra University (Algeria) to test the ability to use EAHE as an alternative solution to conventional air conditioning systems. Besides, a transient numerical approach for the flowing air within the EAHE was developed using energy balance equations, discretised by the implicit finite differences method and solved by Thomas method. Furthermore, the transient temperature profile of the soil around the EAHE was investigated in order to determine the adiabatic radius of the soil as a function of the duration of operation. In this context, a transient semi-analytical model was integrated to the air model to estimate the transient EAHE’s performance deterioration. This deterioration is produced by the thermal saturation of the soil, which is influenced by the heat released from the air inside the pipe. Results showed that continuous operation for a duration of four days has minimal impact on the outlet air temperatures due to the implementation of night purging. Furthermore, the design and thermal efficiency of the EAHE are impacted by factors such as higher air velocity and reduced soil thermal conductivity.

Experimental investigation of effect of extent and position of bypass openings on performance of a single unit liquid desiccant based indirect evaporative cooler

In high temperature and high humidity zones, evaporative cooling is ineffective and vapour compression systems are less energy efficient. Therefore, an alternative system is highly desirable which is effective, energy efficient and enables the use of cheap and sustainable energy sources. Indirect evaporative cooling helps in retaining humidity level of air, but is less effective in attaining lower air temperatures. To mitigate this challenge, M-cycle indirect evaporative cooling system helps in achieving sub-wet bulb temperatures. In this work, performance of a novel modified indirect evaporative M-cycle cooling system assisted by 40% aqueous Li-Cl liquid desiccant is experimentally investigated against various parameters. The cooling system used in this study is a single unit system which can perform indirect evaporative cooling, liquid desiccant dehumidification and internal cooling to the liquid desiccant. With an air velocity of 1 m/s at the inlet, the introduction of openings in between inlet and exit of the cooling system has shown a maximum improvement of 19.2% in its dew point effectiveness, with unaffected dehumidification effectiveness. Furthermore, it is observed that the dew point effectiveness is decreased with the increasing distance of openings from the inlet. The investigated cooling and dehumidification system is useful as a pre-air-conditioner to conventional air-conditioning systems and also as a stand-alone air-conditioning system.

Sex-based thermal comfort zones and energy savings in spaces with joint operation of air conditioner and fan

Fan and air conditioner combined systems (FACS) have been demonstrated as a viable alternative to conventional air conditioning systems, providing thermal comfort to occupants while consuming less energy. However, few studies have quantitatively established occupant comfort zones for FACS operation and analyzed its energy saving effects. An experiment was conducted first to develop thermal comfort zone in spaces with FACS operation. As the indoor temperature rises, the upper limit of air speed accepted by occupants increases. Females exhibit an upper comfort range parameter of 29.8 °C and 1.4 m/s, while males demonstrate 29.3 °C and 1.5 m/s. There are noticeable differences in comfort ranges between males and females, especially in cooler conditions. Based on the established comfort zone, energy simulation studies were conducted for most regions of China to investigate the potential energy savings resulting from the implementation of FACS in ASHRAE standard office building. Buildings incorporating FACS demonstrate a reduction in HVAC system energy consumption by more than 16 % when compared to indoor temperature set at 26 °C. In hot summer and warm winter climates, HVAC system energy savings of over 100 GJ/year can be achieved using FACS for the standard building. Considering sex differences in FACS operation leads to additional energy savings.

Performance Evaluation of Different Desiccant Matrix Materials Coated with Silica Gel

ABSTRACT Excessive cooling of air is required in conventional air conditioning systems to reduce the humidity, leading to the development of desiccant wheel-based air conditioning systems. The desiccant wheel consists of desiccant material which is deposited on matrix material. In this study, aluminum, magnesium alloy, Teflon and fiberglass have been considered matrix materials of the desiccant wheel. A one-dimensional mathematical model has been developed to evaluate the effect of these matrix materials. The results show that fiberglass can be selected as a suitable matrix material for drying applications because it has maximum moisture removal (1.92 g/kg) and temperature difference (4.72 °C) at optimal rotational speed, which are desirable for drying. While aluminum can be selected as a suitable matrix material for air conditioning applications because, at the optimal rotational speed, it has lower maximum moisture removal (1.26 g/kg) and temperature difference (3.14 °C) as compared to other matrix materials. As moderate maximum moisture removal and lower temperature difference are the requirements for air conditioning. A similar trend of results has been also obtained for other parameters (volume ratio, regeneration velocity, regeneration temperature, etc.) of this study.

Impact of indoor heat load and natural ventilation on thermal comfort of radiant cooling system: An experimental study

Construction and operation of buildings are responsible for about 20% of the global energy consumption. The embodied energy of conventional buildings is high due to the utilization of energy-intensive construction materials and traditional construction methodology. Higher operational energy is attributed to the usage of power-consuming conventional air-conditioning systems. Therefore, moving to an energy-efficient cooling technology and eco-friendly building material can lead to significant energy savings and CO2 emission reduction. In the present study, an energy-efficient thermally activated building system (TABS) is integrated with glass fiber reinforced gypsum (GFRG), an eco-friendly building material. The proposed hybrid system is termed the thermally activated glass fiber reinforced gypsum (TAGFRG) system. This system is not only energy-efficient and eco-friendly but also provides better thermal comfort. An experimental room with a TAGFRG roof is constructed on the premises of the Indian Institute of Technology Madras (IITM), Chennai, located in a tropical wet and dry climate zone. The influence of indoor sensible heat load and the impact of natural ventilation on the thermal comfort of the TAGFRG system are investigated. An increase in internal heat load from 400 to 700 W deteriorates the thermal comfort of the indoor space. This is evident from the increases in operative temperatures from 29.8 to 31.5 °C and the predicted percentage of dissatisfaction from 44.5% to 80.9%. Natural ventilation increases the diurnal fluctuation of indoor air temperature by 1.6 and 1.9 °C for with and without cooling cases, respectively. It reduces the maximum indoor CO2 concentration from 912 to 393 ppm.

EN Energy efficiency improvement for the older reefer vessel by the combined compression-ejector refrigeration machine

A marine combined compression-ejector refrigeration machine that comprises conventional refrigeration and air-conditioning system using single-stage refrigeration machine and an ejector refrigeration machine is proposed and studied. The ejector refrigeration machine is driven by the waste heat from the single-stage refrigeration machine and acts as the bottom cycle of the single-stage refrigeration machine. A system analysis shows that the COP of a compression-ejector refrigeration machine is significantly higher than a one-stage refrigeration system. Improvement in COP can be as high as 19.3% for evaporating temperature of the single-stage refrigeration machine Tc at -40°C. Influence of flowing part of ejector profile, operating parameters, scheme and cycle of the marine combined compression-ejector refrigeration machine on its performance characteristics is shown. Rational methods to increase efficiency of marine combined compression-ejector refrigeration machine, operating with environmentally friendly low-boiling refrigerant R245fa, are offered and investigated. The present study shows that the combined compression-ejector refrigeration machine using the ejector refrigeration machine as the bottom cycle of the one-stage refrigeration machine is viable. The opportunities of implementing solar panels, raised challenges for older reefer vessels (20-40years) force to analyse situation. While opportunities exist for efficiency improvement and environmental alignment, challenges in retrofitting older vessels, especially those nearing the end of their operational life, make economic viability a critical consideration. The analysis of the possible solar panel application estimates a cost range of 398,269.20 to 426,717.00 euros, emphasizing the need for careful evaluation. The conclusion advocates against implementing solar panels on the researched vessel, highlighting the lack of justification in both economic and operational efficiency aspects