cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.18462/iir.gl.2018.1213
title: Theoretical evaluation of cooling and heat-pump operation of an environmental test chamber using CO2 as refrigerant.

description: The introduction of the EU F-Gas Regulation results in a strict schedule for phase-down and a ban of synthetic high-GWP refrigerants. Small industry sectors like environmental simulation are affected as well. The refrigerants R404A and R507 will be banned for new installations in 2020. Recent announcements of supply constraints and a massive price increase led to the question whether or not new drop-in alternatives are available. CO2 is a well-known and future reliable alternative in various applications and comes into focus for the environmental test industry. This work proposes a concept for an environmental test chamber using CO2 as refrigerant. Typical test procedures require temperatures below and above ambient. Cooling as well as heating is therefore necessary. The proposed concept allows both cooling and heat-pump mode. Furthermore a system simulation was used for a comparison of the total energy consumption for a specific test procedure between a baseline electrically heated environmental test chamber with R452A and the proposed concept. The results show reduced energy consumption for heat-pump mode which allows heating in wide range of the temperature requirements. However, an additional electrical heater is still necessary to cover temperature above 60°C. The cooling mode of the proposed concept is comparable to the baseline cooling cycle with respect to energy consumption.
DOI: 10.18462/iir.gl.2018.1272
title: Two-stage high temperature hybrid heat pump with parallel heat sinks.

description: Hybrid heat pumps have operated well at temperatures above 100ºC for a decade and several improvements have been made during this period. Heat delivery at two temperature levels with a single, integrated heat pump with two absorbers in parallel is yet not exploited. Thus, current solutions deliver to one heat demand, even though industries often have several heat demands at various temperature levels; a more efficient and advanced solution should be able to deliver heat at several temperature levels. An ammonia/water hybrid heat pump was simulated at various loads, achieving ratios of delivered heat to work input in the range 2.1-2.8. Both static and dynamic simulations were performed, and values for storage capacities to even the loads were predicted. The system manages to operate and deliver the requested capacities from both 20°C and 27°C bottom cycle refrigeration, and achieves required setpoint at all loads, steady and dynamic ones. The COP at 20°C bottom cycle might be not acceptable for commercialization, whereas at 27°C the COP values are improved by 15% (total COP), 18 % (HT COP) and -18% (LT COP).
DOI: 10.18462/iir.gl.2018.1324
title: Experience with industrial refrigerating systems for southern climate.

description: For the northern climate, nobody doubts the advantages of CO2 as a refrigerant, especially in retail applications and food processing plants. For the southern climate however, there are still some doubts in terms of efficiency. There are more and more CO2-installations in operation, equipped with efficiency increasing technology such as parallel compression or ejectors. The increasing number of CO2-installations and growing experience allows proving the predictions in terms of efficiency that optimised CO2- installations can outclass state of the art refrigerating systems, even in southern climate. In summer 2017, two transcritical CO2 racks with multi-ejector and parallel compression have been commissioned near to Valencia, Spain. The two racks are installed in a fish processing plant and replace a previous installation with R507A. The CO2-system is designed to maintain ultra-low temperature at -40°C, low temperature at -20°C and medium temperature at +2°C. The total cooling capacity of the systems is 764 kW. This paper highlights the main issues, why CO2 has been the preferred refrigerant by the end user compared to traditional ammonia systems.
DOI: 10.18462/iir.gl.2018.1387
title: Integration of geothermal storage in CO2 refrigeration systems of supermarkets.

description: The aim of this paper is to study the benefits of integrating CO2 transcritical booster refrigeration system with geothermal storage. The ground is used as a heat sink for sub-cooling during the summer period and as a heat source for extracting heat in the winter season. Using field measurements from medium size supermarkets in Sweden, proposed and the existing system solutions for integrating geothermal storage in CO2 refrigeration systems are modelled and compared with standard CO2 transcritical booster system. The techno-economical comparative analysis shows that hybrid CO2 transcritical booster system with ground source heat pump (GSHP) as an integrated geothermal solution has 6% lower annual energy use compared to a stand-alone CO2 system with heat recovery.
DOI: 10.18462/iir.gl.2018.1391
title: Comparison of state-of-the-art CO2 alternative refrigeration systems for supermarkets.

description: This paper investigates the state-of-the art features of CO2 trans-critical booster systems. The performance of various modified features have been compared to the standard CO2 booster system. Subsequently, the performance of the defined state-of-the-art CO2 system is compared to natural refrigerant-based cascade, HFC/HFO-based DX and indirect refrigeration solutions, and propane water-cooled plug-ins operating in cold and warm climates. The results indicate that flooded evaporation and parallel compression are the most promising features of the state-of-the-art CO2 system. This compact and environmentally friendly system is the most energy efficient solution in cold climates, and is also an efficient solution in warm climates, with comparable efficiency to cascade and HFC/HFO DX systems, but with no existing or potential limitations.
DOI: 10.5281/zenodo.1442593
title: A Bibliometric Analysis Of The Term "Anthropocene"

description: This repository contains data and code to reproduce a small bibliometric analyses of the term "Anthropocene" that is part of a submitted paper to the journal "Progress in Physical Geography"
DOI: 10.5281/zenodo.1442594
title: A Bibliometric Analysis Of The Term "Anthropocene"

description: This repository contains data and code to reproduce a small bibliometric analyses of the term "Anthropocene" that is part of a submitted paper to the journal "Progress in Physical Geography"
DOI: 10.18462/iir.gl.2018.1114
title: Techno-economic analysis of a photovoltaic-driven R290 chiller with a phase-change-material (PCM) storage tank for refrigeration applications.

description: This article examines whether the use of electrical or thermal storage is economically feasible for photovoltaic plants supplying power to a cold store. It is assumed that the PV plant does not receive a feed-in tariff for the electricity generated and that the PV plant cannot feed excess electricity into the grid. It is shown that economic operation with storage is possible, but a reduction of the storage costs is necessary. In the case of a storage tank with phase change material and an installed PV peak power of 112 kWp, lower levelized cost of cooling energy (LCCE) can be achieved at specific additional costs for storage below € 44 / kWhth, which corresponds to a required cost reduction of -39%. If a PV peak power of 224 kWp is available this will result in lower LCCE at specific additional costs for storage below € 76 / kWhth, which corresponds to a required cost reduction of -16%. The use of battery storage currently generates higher costs. Lower LCCE for the battery scenario with 112 kWp can only be achieved with additional costs for storage below € 120/kWhel, which corresponds to a necessary cost reduction of -84%. In the battery scenario with 224 kWp, lower LCCE can be achieved below additional costs for storage of € 220/kWhel, which equals a cost reduction of -71%. It can be summarized that both battery and PCM storage allow economic operation for the described cold store if the calculated cost reductions for the individual storage component can be achieved in the near future.
DOI: 10.18462/iir.gl.2018.1117
title: Modeling of S-RAM energy recovery compressor integration in a transcritical carbon dioxide cycle for application in multi-temperature refrigerated container systems.

description: With recent growth in awareness of the environmental impacts of hydrofluorocarbon (HFC) refrigerants, efforts towards the use of natural refrigerants as a replacement have increased dramatically. With these efforts has come the development of system components designed and optimized for the unique challenges surrounding these working fluids. The natural refrigerant carbon dioxide (CO2) has spiked particular interest for military application due to its global warming potential (GWP) of 1, low cost, high energy density, being non-flammable, and ease of maintenance. This research focuses on the development of a simulation model of a transcritical CO2 cycle for use in a U.S. Army Multi-Temperature Refrigerated Container System (MTRCS). The MTRCS has two compartments, each with variable cooling capacity and temperature. The core technology for the proposed transcritical CO2 cycle is a novel Energy Recovery Compressor (ERC) that utilizes the Sanderson-Rocker Arm Mechanism (S-RAM). The ERC is a two-stage compressor combined with a single-stage expander in one unit. This paper discusses the inclusion of the volumetric flow ratios of the ERC compression and expansion stages into the transcritical CO2 cycle model and presents results on the effects they have on the system operation and performance. The model is able to predict over and under-expansion at various operating conditions, considers these effects on overall system performance, and captures the effects of expander isentropic efficiency variation on the entire system performance. In addition, the next steps for further model improvements and the validation of model predictions through experimental results are provided.
DOI: 10.18462/iir.gl.2018.1126
title: Alternative refrigerants for the primary circuit of an indirect commercial refrigeration cascade system.

description: F-Gas Regulation has fixed a GWP limit of 150 for centralized refrigeration systems with capacity over 40 kW in Europe from 2022 on, meaning the end of R-134a as primary refrigerant in direct R-134a/CO2 cascade systems. They can be reconverted into indirect cascades using a secondary loop, bringing the possibility to use primary refrigerants with reduced security. This communication presents the experimental results of the energy evaluation of an indirect cascade using CO2 as low temperature refrigerant and different refrigerants in the high temperature cycle (R-134a, R-152a, R-1234ze(E), R-290 and R-1270). The system serves a medium temperature cabinet and a low temperature island placed inside a climatic chamber under laboratory conditions. The evaluation covers three heat rejection levels (18.9, 31.8 and 42.3ºC).
DOI: 10.18462/iir.gl.2018.1171
title: Investigation on the performance of an absorption heat exchanger operating with seven aqueous-based working pairs.

description: Paper published in poster form during the conference. The performance of absorption heat exchanger operating with seven working pairs with water as refrigerant is studied. The operating condition is set according to the heating network parameters. The outlet temperature of the primary water is used to evaluate the performance. To find out how different the working pairs are, we use total KA (the sum of heat transfer coefficient times heat transfer area in each component) to represent their heat transfer capability and coefficient of lift to quantify their VLE (vapor-liquid equilibrium) property, while the solution flowrates are optimized to achieve the lowest outlet temperature. The outlet temperature trend shows conclusively that a better performance occurs when heat transfer capability and thermodynamic property compromise.
DOI: 10.18462/iir.gl.2018.1189
title: Design and optimized operational strategy of a district cooling and heating system based on ground source heat pumps.

description: Paper published in poster form during the conference. A comprehensive district heating and cooling (DHC) system design is presented. Large-scale ground source heat pump (GSHP) with thermal energy storage system is applied in the DHC system. Normally, the compressor of a ground source heat pump works at a very wide range of compression ratios, and thus the annually overall performance is comparatively low. Through simulation evaluation, the annual cooling and heating performance of the ground source heat pump is enhanced by increasing the mean temperature of the ground and thus narrowing the work range of compression ratios. The hourly operation strategy of the heat pumps and thermal storage system is proposed to decrease the energy cost and match the tiered pricing of power consumption. In addition, heat pumps always work near the maximum efficiency point by utilizing the coordinated thermal energy storage system.
DOI: 10.18462/iir.gl.2018.1255
title: Study on CFD analysis of refrigerant leakage and ignition source about built-in refrigerated display cabinet using R290.

description: In order to tackle the global warming, the use of A2L refrigerants has been focused on and investigated in Japan. Risk assessments of a variety of appliances have been carried out, resulting in the establishment of methods for ensuring safety of the appliances using A2L refrigerants. However, there still remains the influence of the refrigerants on global warming, and it is desired to convert to lower GWP refrigerants. Almost all of the refrigerants with low GWP values tend to have relatively high flammability and there could be a danger of explosion that causes fire. For flammability risk evaluation of the built-in refrigerated display cabinet using R290 in the event of refrigerant leakage, flammable volume-time integration and duration of flammable region necessary for the risk assessment were calculated through CFD analysis in this paper. In addition, potential ignition sources such as static electricity were investigated and discussed.
DOI: 10.18462/iir.gl.2018.1313
title: Measurement of R290 leakage with laser doppler anemometry.

description: Paper published in poster form during the conference. This paper describes the experience made with the measurement of the velocity field of a plume of leaking R290 into an air-filled space with Laser Doppler Anemometry. Two different leak sizes were tested with both liquid and vapour refrigerant .
DOI: 10.18462/iir.gl.2018.1377
title: An experimental analysis of the use of phase change materials in household refrigerators.

description: The aim of this work is to study the effect of applying phase change materials (PCMs) in the cold and warm sides of HC-600a household refrigerators. To this end, two types of PCMs were applied in the freezer and three in the fresh-food compartment. Three types of PCMs were also integrated into the wire-and-tube naturaldraft condenser. Pull-down, pull-up and energy consumption tests were carried out with each system configuration for comparison with results for an off-the-shelf household refrigerator. It was found that the pullup time increases when PCMs are placed in the refrigerated compartments, regardless of the type, amount or location, with a minor impact on the energy consumption. In contrast, energy savings of up to 5.4% were achieved with the integration of water slabs into the condenser, with this percentage being strongly dependent on the compressor on and off times.
DOI: 10.18462/iir.gl.2018.1111
title: Generating hot water for food processing plant using waste heat, high temperature heat pump and storage.

description: This paper presents a novel concept to supply hot water to a food processing plant by upgrading surplus heat from a refrigeration system by means of a high temperature heat pump (delivering heat above 100°C). The system utilizes thermal storage and district heat as backup, replacing the currently used electric boilers. Savings for six different system solutions are presented, aiming to find the most sustainable and efficient solution. The savings for the best practice solution were about 41-49% of CO2-emissions, 39-51% of electricity and 29-57% of district heat.
DOI: 10.18462/iir.gl.2018.1135
title: Possible configurations of multiejector driven CO2 systems for Indian supermarkets.

description: Paper published in poster form during the conference. An Integrated CO2 Refrigeration Facility is designed for hot climate conditions to improve the basic knowledge of the CO2 refrigeration in India, especially in the supermarket sector. The operational modes can be adapted to simulate different applications. The gas cooler outlet temperature can be regulated to simulate various ambient conditions. For Southern India, a parallel compression configuration with ejectors for expansion work recovery is the most efficient mode. It can deliver and perform freezing, refrigeration and air conditioning loads, and has a heat reclaim option. The different operation configurations help to understand the behavior of CO2 refrigeration for a wide range of applications as well as reveal the respective influences between components. The most interesting is, the possibility to demonstrate the feasibility of R744 transcritical systems as a non-HFC based alternative to HCFC-22 in retail applications in countries with high ambient temperature. The CO2 refrigeration test facility is a preparation and demonstration site for a full-scale replacement of existing commercial refrigeration installations in India.
DOI: 10.18462/iir.gl.2018.1141
title: Measurement of oil circulation in transcritical R744 systems using two-phase ejector.

description: The use of two-phase ejectors to recover expansion work to improve COP of transcritical R744 systems has been the subject of numerous investigations during the past decade. However, there is little understanding as to how oil in circulation in different parts of the system is affected when a two-phase ejector is used to replace the expansion valve. This paper presents detailed measurement results conducted on a transcritical R744 ejector system using polyalkylene glycol (PAG) oil, demonstrating that at the same test condition, the oil circulation rates (OCRs) in different parts of the system can easily vary by an order of magnitude. The highest OCRs of approximately 10% by mass were measured close to the evaporator inlet. The influence of compressor speed, ejector motive nozzle needle position and evaporator inlet metering valve opening on the OCRs was investigated and it is explained why these condition changes will result in variation of oil in circulation.
DOI: 10.18462/iir.gl.2018.1147
title: A new approach to performance data harvesting and processing in commercial refrigeration systems.

description: New lay-outs for commercial refrigeration systems, mainly based on CO2, have been progressively replacing HFC ones. Their performances are typically evaluated thermodynamically, resulting in difficult comparison amongst systems. The refrigeration unit could in principle be certified similarly to other appliances; however technology is rapidly evolving, adapting to climates and customers’ requirements, like integration with AC, making systematic laboratory testing a challenge. Moreover, plant design and management heavily affect overall efficiency. Therefore, the evaluation of efficiency requires collection of data from the field. Despite commercial refrigeration systems are fully equipped with monitoring devices easily accessible and transparent information about performance and energy efficiency are often lacking. Together, there is increasing demand for key parameters that can help in forecasting performance degradation of the entire system or of single components, to prevent costly failures. A new approach to data collection and processing is presented and its potentialities illustrated by preliminary field data.
DOI: 10.18462/iir.gl.2018.1166
title: Development and validation of a CO2 gas cooler moving-boundary model.

description: This paper presents the development of a CO2 gas cooler model using the moving-boundary method. The model aims to separate the gas cooler into two regions: supercritical gas and supercritical liquid by means of the CoolProp thermophysical property library (Bell et al., 2014). The model uses the latest correlations for refrigerant and air-side heat transfer coefficients and pressure drops. The experimental results from Ge and Cropper (2009) are used for model validation. A total of at 36 operating conditions have been reported. The model predicted the gas cooler heating capacity within an MAE of ±4.7% and refrigerant side outlet temperature within ±3 K. The present moving-boundary model also showed an improved agreement compared to the segment-by-segment model proposed by Ge and Cropper (2009).
DOI: 10.18462/iir.gl.2018.1221
title: Silmultaneous power with cooling and heating systems using ammonia absorption trigeneration technology for commercial buildings.

description: A novel absorption based trigeneration technology for building energy applications was conceptualized and presented. A GAX based ammonia absorption integrated Kalina power cycle provide simultaneous useful outputs of cold, heat and power. A thermodynamic model was developed to analyse the system performance and parametric analysis was carried out to estimate the combined output capacity for a wide range of operating conditions. At low sink temperature below 25°C, the system is capable of providing 100 -310 kW of heat output, 140 -182 kW for net power output with effective first law and exergy efficiencies are 40% and 15% respectively and at high sink temperature above 30°C, 20 -100 kW cooling, 110-132 kW net power output with effective first law and exergy efficiencies are 44% and 17% respectively. The cycle was found to be very attractive for winter heating and summer cooling, at better year-round system performance.
DOI: 10.18462/iir.gl.2018.1225
title: Ammonia as natural refrigerant in electrically and thermally driven engines for heat pumps.

description: Ammonia is an excellent refrigerant for use in absorption or in vapor compression heat pumps because of its favorable thermodynamic and heat transfer properties. We examine the choice of driving a heat pump with a thermally-driven (TD) engine as in the case of an absorption device, or with an electrically-driven (ED) engine, as in the case of a Rankine cycle heat pump. Which engine has a lower carbon footprint and has the least environmental impact is the quintessential issue discussed in this presentation. The question is examined through a comprehensive methodology of energy and exergy analysis which explains why the output of these two engines is so different, and what impact it makes for source energy consumption, and environmental stewardship. This work is a fundamental analysis which discusses the choices and consequences of ED versus TD heat pumps and its direct impact on the environment. Thermodynamic consistency is guaranteed by invoking the First and the Second Laws applied to various components and subsystems of the TD and ED heat pumps.