cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.18462/iir.gl.2018.1373
title: Energy evaluation of drop-in replacements for R134a in cascade CO2/R134a refrigeration units.

description: The energy performance of CO2 standard booster systems is limited in countries with high ambient temperatures to replace R404A direct expansion architectures. Therefore, cascade refrigeration systems with CO2 in the low-pressure stage can be considered. Most of the conventional cascade refrigeration systems rely on using R134a, a high global warming potential (GWP) refrigerant, in the high pressure stage. However, R134a needs to be replaced by lower GWP refrigerants to meet the targets of current environmental agreements. This study investigates R450A and R513A refrigerants as drop-in replacements to R134a in R134a/CO2 cascade refrigeration units. The experimental energy performance results suggest that both R450A and R513A can substitute R134a in cascade systems. R513A provides comparable COP and cooling capacity values to R134a, whereas the cooling capacity and COP of R450A are lower than that of the baseline R134a.
DOI: 10.18462/iir.gl.2018.1374
title: Performance enhancement of vapor compression heat pumps by a cooled compression cycle.

description: The presented study proposes a configuration combining the compression and condensation processes in a single unit and evaporation and expansion in another separate unit for application in a vapor compression heat pump cycle. The cycle includes injection of refrigerant into the compressor at a certain temperature. This system makes it possible to match the temperature glide of the heat sink and source and simultaneously condense the refrigerant during the compression. A mathematical model of a complete cycle was made to study the system parameters and performance improvement of the cycle. Moreover, thermodynamic models of compression-condensation processes as well as a sensitivity analysis were developed to investigate the heat transfer inside the compressor-condenser unit and determine the injection conditions which can achieve the desirable requirements in the cycle model. Advantages such as eliminating thermodynamic losses associated with the desuperheating of refrigerant, reduction of compression work, available hot liquid at the compressor outlet for the district heating system and COP closer to the Lorenz COP can be obtained compared to the conventional cycle. The proposed cycle reached COP of 4.1 and 59 % Lorenz efficiency for a case related to R717 as working fluid and district heating production.
DOI: 10.18462/iir.gl.2018.1396
title: Modulating two phase ejectors in transport refrigeration.

description: The need to safely reduce refrigerant global warming potential in the transport refrigeration industry has led to the introduction of R-744 (CO2) refrigerant systems for ocean containers and road trailers. Containers operate over a wide range of ambient and set temperature requirements that demand precise temperature management for customer acceptance. CO2 modulating ejector technology has been investigated for potential performance benefits relative to container transport applications. This material will include background information for the system-level changes required and technologies used today in CO2 container refrigeration systems that meet product requirements. Additionally, this study will detail the work done around the development, model-based analysis and system performance results to evaluate and understand the potential benefits of CO2 modulating ejector technology in transport applications.
DOI: 10.18462/iir.gl.2018.1105
title: Safe design of R290 ducted air-conditioning equipment.

description: Currently R290 is used in certain types of air conditioning equipment, such as mini-splits, portables, window units and chillers. Application in ducted air conditioning has hitherto been limited to one-off trials. This study describes the interim findings of a project implemented by UNDP and funded by the MLF of the Montreal Protocol, to develop a range of small capacity ducted packaged (“rooftop”) and ducted single split air conditioners. The main areas of investigation include system design and optimisation (whilst minimising refrigerant charge), determination of leak amounts and options for leak control and characterisation of refrigerant concentration behaviour arising from a leak. Unlike the afore-mentioned types of air conditioning equipment, ducted equipment possess certain features that infer potential technical challenges where it concerns applying R290 safely. These are primarily the distribution of leaked refrigerant through ducting and from non-ducted air return configurations whilst the indoor unit is positioned within closets. Findings and developed measures are described.
DOI: 10.18462/iir.gl.2018.1123
title: Energy distribution concepts for Urban Supermarkets including energy hubs.

description: An increasing share of the population on earth is living in urban areas. Using urban building plots for combined purposes will be important in the future. Investors are interested in building new building concepts that includes a supermarket, apartments and parking lots with energy supply hubs for electric/hydrogen vehicles. A design for this building concept was carried out, and suggestions on integrating a supermarket CO2 refrigeration system and a hydrogen refueling station (HRS) with the centralized heating system in the building was proposed. Heat recovery from the refrigeration system and HRS to space heating (SH) and domestic hot water (DHW) was implemented. Simulations in Dymola show 100% of the yearly DHW demand for 30 apartments of 93.000 kWh can be satisfied by heat recovery. For SH, scenarios for different seasons was investigated, and results show the heat recovery share ranged from 31 to 100% by varying hydrogen production from 0 to 200 kg/day.
DOI: 10.18462/iir.gl.2018.1136
title: Environment-friendly refrigeration packs for Indian supermarkets: experimental investigation of energy performance of a multiejector-driven R744 integrated compressor rack.

description: 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 as well as 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 (mode 4). It can deliver 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. A first test phase running mode 4 for an ambient temperature of 46°C and various receiver pressures in a range of 44 bar - 50bar, proves 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.2018.1140
title: Supermarket demand response using the CO2 booster cycle: model development, validation, and simulations of load shed events with CO2 booster systems.

description: Transcritical CO2 booster systems are becoming more popular in North America, as federal and state regulations push the phase-down of HFC refrigerants. At the same time, the use of refrigeration systems for demand response – functions to increase, decrease, or shift electric load in response to utility needs – is gaining interest as better and less expensive communication and controls become more common. In the Booster cycle, the medium temperature and low temperature stages of the booster cycle are inherently interlinked, so a temporary interruption of one stage may impact the other. This paper describes the use of a transient CO2 booster cycle model to study the impact of load-shed events on overall cycle performance and behavior. The results show the relative “return” (kW total power reduction per kW of load shed) for demand response on each stage and the impact of sheds on each stage on overall behavior. In a system with a roughly 2:1 load ratio, the power reduction of 0.85-0.91 kW per kW of load shed was seen with LT capacity reductions, compared to 0.59-0.60 kW per kW of load shed with MT capacity reductions.
DOI: 10.18462/iir.gl.2018.1154
title: The application of carbon dioxide to small industrial refrigeration systems.

description: Significant effort is being applied to the improvement of efficiency in transcritical carbon dioxide refrigeration and heat pump systems, particularly for higher ambient temperatures. The system configuration known as the low pressure receiver (LPR) is particularly well suited to this application and can be arranged for single stage or two-stage operation. This paper examines the LPR system as used in carbon dioxide systems and compares this with other methods of applying carbon dioxide, and with a standard R-404A DX system which has been the standard solution for this application for many years. The paper provides some calculated values for the different systems under discussion and then discusses performance figures from installed systems to verify the calculations. The parameters considered in the study include efficiency, reliability, simplicity, maintainability and the likely degradation of performance over time (a factor which is usually ignored when comparing and contrasting systems). Capital cost and opportunities for future development are also examined.
DOI: 10.18462/iir.gl.2018.1360
title: Performance evaluation method of CO2 heat pump driven refrigerated display cabinets.

description: An annual energy performance evaluation method for open refrigerated display cabinets (ORDC) driven by CO2 heat pumps in supermarkets is established to predict the annual heat load, energy consumption, COP and total CO2 emissions. Significant condition variations that affect the system performance are considered. The system is thermodynamically modelled with reference to the actual equipment. Experimental data at a comprehensive range of operative conditions are fitted then the characteristic equations for both the heat load of the ORDC and energy consumption of the condensing unit are obtained. The seasonal and climatic condition changes are accounted by integrating the available annual outdoor temperature data of the store location on the performance calculation. Relative error between the estimated energy consumption and experiment stays within ±20%. The constructed tool is capable of predicting the performance of multiple combinations of different ORDC types and can therefore be used for benchmarking, identifying energy conservation opportunities, and assessment of GHG emission.
DOI: 10.18462/iir.gl.2018.1388
title: System efficiency and energy saving with parallel compression and ejectors under flooded conditions.

description: In the recent years various installation of CO2 systems consisting of parallel compression and ejectors has emerged on the market. The installations include the MultiEjector system provided by Danfoss which is consisted of a number of fixed geometry ejectors operating in parallel. The ejectors can function both with vapor, unloading the compressor, and liquid as pump enabling flooded operation of the evaporators. Installations have been commissioned in various locations with different climate characteristics.
The paper present field data from one supermarket installation consisting of parallel compressors and ejectors supporting flooded operation. The purpose is to evaluate the level of energy savings that can be the obtained running the system flooded. The installation was operated in respectively a superheated and flooded configuration to investigate the benefits of running the system with flooded evaporators versus dry expansion mode. The performance was evaluated based on energy measurements and the computed system efficiency (COP), the data shows an improvement in medium temperature COPMT of 30% and estimated reduction yearly energy consumption of 4.5% corresponding to 13050 kWh – running flooded vs. dry expansion mode.
DOI: 10.17632/mwwk6rb364.1
title: Data for: A simple equation to quantify the effect of frequency of light/dark cycles on the photosynthetic response of microalgae under intermittent light.

description: Photosynthesis intensity as specific oxygen generation rate (mole O2 per second and gram of biomass) vs light/dark frequency under different light regimes.
DOI: 10.18462/iir.gl.2018.1116
title: Modeling and control strategy of a transcritical carbon dioxide cycle for application in multi-temperature refrigerated container systems.

description: Transportation refrigeration requires efficient, compact, and reliable technology, and these constraints must be met with especially rugged designs when used in a military application. Additionally, industry trends towards efficiency and environmental concerns have motivated the development of low global warming potential (GWP) refrigerants and efficient technologies to utilize them. This research focuses on the theoretical analysis and physical design of a transcritical carbon dioxide (CO2) cycle for application in a U.S. Army Multi-Temperature Refrigerated Container System (MTRCS). The MTRCS has two separate refrigeration compartments of variable size and operating temperature. The proposed transcritical CO2 cycle utilizes a novel compressor-expander unit called the Energy Recovery Compressor (ERC), which is an axial multi-piston compressor-expander that uses the Sanderson Rocker Arm Mechanism (S-RAM) to convert the shaft rotation into linear piston movements. Integrating the ERC into novel refrigeration system architecture results in a coefficient of performance (COP) of 1.29 at an ambient air temperature of 57.2 °C. In order to achieve this performance, the cycle utilizes three compression stages, intercooling between the 2nd and 3rd compression stages, flash tank economization, and expansion work recovery. The inclusion of these cycle modifications increases the complexity of the system control strategy significantly, and requires the investigation of how important cycle parameters need to be controlled over the range of given operating conditions. This paper describes the system architecture and the analysis conducted to predict the system performance and necessary controls for robust operation.
DOI: 10.18462/iir.gl.2018.1214
title: Interest of ammonia-water absorption chiller to enhance closed cycle gas turbine performance during peak demand comparison with centrifugal chiller.

description: Paper published in poster form during the conference. The study concerns a heat-to-power cycle at a maximal temperature of 515°C generating 300 MWe. The specificity of the work is to consider an alternative cycle to traditional Rankine machine in order to avoid high pressure steam. The selection falls on a high pressure nitrogen turbo-compressor in a recuperated and intercooled Brayton cycle. Within a regulatory framework, the system is required to participate in the primary and secondary frequency settings. This leads of having the capacity to keep a reserve of electrical power to be provided to the grid on demand coming from the electrical network management. A very effective means is to cool the fluid at compressor inlet. Furthermore thermal energy storage tanks are used to charge and discharge thermal energy produced by a chiller. Two technologies of chillers are compared to accomplish cooling: ammonia-water absorption chiller and HFC (HydroFluoroCarbons) centrifugal chiller. Criteria for evaluation are: size, net power production and CAPEX (CAPital EXPenditure).
DOI: 10.18462/iir.gl.2018.1271
title: Performance comparison of different design scheme of absorption boiler.

description: To save energy and reduce emission, single-effect absorption heat pump (AHP) was studied to meet the increasing building heating load. However, this cycle cannot work normally under extreme low temperature ambient, while the building heating load still needs to be met. Therefore, an absorption boiler is proposed in the present study, including AHP mode and boiler mode. These two modes are separately designed under the same working condition, and then 4 different design schemes are compared with each other. The better scheme is the UA values of AHP mode with the generator and preheater UA values of boiler mode. The heating capacity of this scheme is 2.34%-5.95% higher than those of other schemes, and the sum of its UA values is 17.72%- 34.6% smaller than others.
DOI: 10.18462/iir.gl.2018.1306
title: Analysis of R744 refrigeration system with liquid ejectors.

description: In recent years, there is a rapid increase in the cooling demand. Hence, not only the consumption of energy, but also the quantity of the refrigerants released into the air is increasing globally leading to planetary heating. Carbon dioxide (CO2, R744) is a natural refrigerant which is emerging as a potential replacement for HFCs and HCs nowadays because of its attractive properties. However, to avoid liquid entry into the compressor, conventional systems are designed and optimized to keep the exit part of the evaporator dry ensuring no liquid exits the evaporator. This requires superheating of the fluid which also contributes to internal irreversibility leading to lower COP. Hence, the liquid ejectors appeared as the potential option to improve the system COP, by facilitating complete use of the evaporator by avoiding superheating and securing a safe return of liquid refrigerant. This paper presents experimental results of a transcritical R744 system using a liquid ejector. Main aim of the present study is to use a liquid ejector to eliminate superheating of an evaporator and to made a comparison between its ON/OFF switching operation on the overall performance at high ambient temperature conditions (46°C) and its performance. It is observed that the increment in evaporator pressure and decrement in compressor power consumption are 4.5% and 5.5% respectively. Also, from the reduced superheat, it is evident that the proposed design can address the problem of uneven use of heat transfer area in the evaporator due to nonlinear refrigerant distribution and contribute to energy saving.
DOI: 10.18462/iir.gl.2018.1329
title: Hydrocarbons vaporization inside a 4mm ID horizontal smooth tube.

description: This paper presents new experimental data collected during R600a flow-boiling inside a 4 mm ID horizontal copper smooth tube. Tests were carried out at 20 °C of saturation temperature, with heat flux ranging from 15 to 30 kW m−2 and refrigerant mass flux in the range 100–300 kg m −2 s −1 at increasing vapor quality up to incipient dryout. On the basis of the heat transfer data, the influence of forced convection and nucleate boiling contributions was investigated. The collected measurements were then used to assess some classical literature correlations. Finally, isobutane heat transfer performance was compared with other hydrocarbons (isobutane, and propylene). These latest measurements were obtained by the same authors under similar working conditions (Longo et al., 2017).
DOI: 10.18462/iir.gl.2018.1371
title: Direct vapor ammonia generation inside a concentrating parabolic trough solar collector for an ammonia/lithium nitrate absorption machine. Theoretical study.

description: Among the renewable energy technologies, concentrating solar collectors are receiving growing interest as power source for heat and electricity production worldwide. The recent development of small scale parabolic trough collectors, PTCs, suggests extending their application to medium and low temperature facilities configuring solar integrated absorption machines for heating and cooling purposes. The innovative solution considered in this work uses the PTCs as a direct vapor generator/separator forming part of an absorption machine using ammonia/lithium nitrate dissolution as working fluid, thus flowing the dissolution inside the collector absorber tube. The gravity driven flow stratification and separation obtained inside the receiver tube ensures a continuous desorption of the refrigerant and enables a simplified system layout, reducing the overall costs and complexity. The 1-D steady-state numerical model of the PTC vapor generator proposed is suitable for approaching a first characterization of the system operation and supports its design and optimization. A theoretical analysis is carried out to identify the influence of the main constructive and operating parameters on the performance of the PTC as direct vapor generator/separator. The results presented evidence its suitability for the indicated purpose.
DOI: 10.5285/749ffa17-ee4f-46a4-8827-5f062af19a6c
title: Carbonate flux in the Northern Scotia Sea from April 2009 to February 2011

description: This dataset is referring to 2-year time series of particle flux, as measured by two deep moored sediment traps (P2, P3) located in the Southern Ocean (northern Scotia Sea sector), a globally important region of atmospheric CO2 drawdown containing both naturally iron-fertilised (P3) and iron-limited (P2) regimes. The dataset includes the main biogeochemical flux parameters (such as Bsi, POC and PIC) as well as the specific contribution of each part of the plankton calcifying community (pteropods, foraminifera, coccolithphores and ostracods) to the PIC within a period from April 2009 to February 2011. The dataset allows the estimation of the Carbonate Counter Pump (CCP), which causes an increase in surface ocean CO2 through the calcification and precipitation of carbonate.
DOI: 10.18462/iir.gl.2018.1170
title: A review of two-phase heat transfer and pressure drop correlations for natural refrigerants in small diameter tubes.

description: The use of small diameter tubes in heat exchangers (HXs) has significant advantages, which include the increase in heat transfer coefficient, reduction in HX size, material, weight, and refrigerant charge. Due to these desirable characteristics and reduction in environmental impact, natural refrigerants become good candidates to substitute HFCs and HCFCs with the application of small diameter tubes. This paper comprehensively reviews the available two-phase heat transfer and pressure drop correlations for natural refrigerants and small diameter tubes (Dh ≤ 5 mm). In addition, the effects of critical Reynolds number and two-phase flow regimes are discussed in the context of small diameter tube. Overall, two-phase heat transfer and pressure drop correlations for this application interest are not sufficient. This paper provides a guideline to choose correlations among existing models and identifies the research topics worthy of future study.