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The world is warming, and the demand for cooling is increasing. Developing a future green hydrogen economy will also increase the demand for cooling for hydrogen liquefaction. This increase in cooling demand will happen mainly in tropical and developing countries due to their increase in population, improvements in quality of life, and the export of their renewable potential with liquid hydrogen. To solve this increase in demand for cooling, this paper proposes the use of ammonia airship cooling (AAC). AAC extracts cold from the tropopause (−80 °C) with airships and ammonia refrigeration cycles. The liquid ammonia is then transported back to the surface to provide low temperature cooling services (−33 °C). This cooling service is particularly interesting for lowering the electricity consumption in hydrogen liquefaction plants. If all the technological challenges mentioned in the paper are addressed, it is estimated that the cost of cooling with the technology is 8.25 USD/MWht and that AAC could reduce the electricity demand for hydrogen liquefaction by 30%. AAC is an innovative renewable cooling technology that has the potential to complement other renewable energy sources in a sustainable future. [ABSTRACT FROM AUTHOR]

This paper presents a new development of an Adaptive Network-based Fuzzy Inference System (ANFIS) for a Hybrid Ground Source Heat Pump (HGSHP). The HGSHP is equipped with a supplementary heat sink composter to process organic solid waste (OSW), utilizing excess hot air from the condensing unit to aerate the compost pile. The Fuzzy Logic Controller (FLC) was developed using data collected by effective sensors installed in the HGSHP system. The main objective is to control the water flow rate with a Variable Speed Drive (VSD) to improve overall system performance. The dataset for ANFIS has been created and trained using MATLAB® software, then implemented on a Raspberry Pi nano-computer with Python coding. This paper compares the performance of ANFIS with two different cases: ANFIS with Triangular Membership Function (TriMF) and ANFIS with Gaussian Membership Function (GaussMF). After implementing ANFIS with TriMF and GaussMF, the average COP during composter operation and system cooling significantly increased. In contrast, the HGSHP system power consumption is sufficiently reduced in both case studies. Moreover, ANFIS also benefits the composting process, as evidenced by the increase in composter operation time, and vice versa for system cooling time. Ultimately, the implementation of ANFIS can improve the HGSHP system performance in both the TriMF and GaussMF cases, with the TriMF case showing a significant improvement in the HGSHP system performance compared to the GaussMF case.

The advance of air-conditioning systems has become a popular topic, due to its huge energy consumption and the increasing demand of improving indoor air quality. Although various approaches have been proposed for humidity, temperature and CO 2 control, their coordination has not yet been studied. In this study, the technologies of desiccant dehumidification, indirect evaporative cooling and direct CO 2 capture are innovatively integrated in an air-conditioning system, by which their respective advantages can be exerted and limitations can be compensated. Under a base working condition with ambient temperature of 35 °C and relative humidity of 80%, the overall coefficient of performance of the integrated system reaches 0.93, with an improvement of 53.3% against a conventional scheme. The integrated system is more efficient at higher crowdedness. With occupant number from 2 to 22 in a room, the advantage of the integrated system ranges from 50.7% to 85.6%. Parametric studies on different indoor and outdoor conditions are conducted, indicating that the energy efficiency advantage is more outstanding at higher indoor temperature, lower ambient temperature and lower ambient humidity. The factors of economic, environment and health are discussed, where the integrated system exhibits superiority against conventional systems and existing studies as well. Approaches are raised to improve the performance and promote future studies. The results in this paper contribute to providing a scheme for the integration of different technologies and enlightening insights for the advance of air-conditioning systems for the sake of air quality improvement, energy saving and emission reduction. • An integrated air-conditioning system is proposed for improving energy efficiency. • Different technologies for temperature, humidity and CO 2 control are coordinated. • 53.3% improvement on energy efficiency is obtained for base working condition. • Parametric analyses indicate advantage for the integrated system at most cases. • Economic and environmental issues are discussed compared with existing studies. [ABSTRACT FROM AUTHOR]

• The price-responsive flexible behaviour of an office building is studied. • The price signals convey changes in temperature setpoints, offering flexible demand. • A step-by-step approach for utilising flexibility in a building is proposed. • The study shows flexibility availability is dependent upon HVAC operational modes. • Demand increases notably for prices ≤ 10 % of the highest value. Flexibility in buildings is a low-cost alternative to support the electricity network with high penetration of variable generation. There is a limited understanding of energy flexible behaviour of the buildings in response to electricity market signals. In this paper, the price-responsive flexible behaviour of a commercial building with a cooling system has been studied. A first-order virtual battery model of the building and flexibility function-based approach have been used to understand the flexible behaviour of the building to varying price signals. The price signals delivered changes in building electricity demand profile, altering cooling temperature set points. The building structural thermal storage capacity was found to vary depending on demand changes. Low price signals provoke positive demand changes with respect to the baseline demand, taking the system to charging mode. Similarly, high price signals lead the system to discharging mode, reducing the instantaneous charging condition of the system. HVAC operating states, e.g., free cooling/economiser cooling and mechanical cooling, have been found to have a notable impact on electricity demand flexibility. The flexibility function shows that for a very low-price value, the cooling setpoint approaches the lowest comfort bound, and demand increases significantly. A deviation between the maximum and minimum electricity demand of 207 kW for the studied building system gives an estimated maximum energy flexibility capacity of 7248.2 kWh. The response of the building to variable price signals yields flexible demand, delivering cost savings of 13 %. [ABSTRACT FROM AUTHOR]

Germany is obliged to report emissions of fluorinated greenhouse gases annually under the UNFCCC. This includes emissions of fluorinated refrigerants when decommissioning RAC equipment. To obtain this information, data on the recovery, recycling, and disposal of fluorinated greenhouse gases is necessary, but such data are scarce. The VDKF-LEC database contains information on the recovery of fluorinated refrigerants from decommissioned RAC equipment in Germany and an extracted dataset was used to obtain real-world information for the years 2017 to 2021. Recovery rates for different fluorinated refrigerants from decommissioned commercial and industrial refrigeration as well as stationary air-conditioning equipment were derived. Furthermore, average lifetimes of equipment for the different sectors were calculated. In the analysis, a dependency of charged refrigerant and age of the unit at decommissioning could be observed. Results from the analysis of the VDKF-LEC dataset were compared with reported data under the UNFCCC for Germany and other available data sources. [ABSTRACT FROM AUTHOR]