Use of Polyurethane Insulated Panel for Heat Infiltration in Refrigerated Vehicles

This study investigates the overall heat transfer coefficient of reinforced composite panel with the aim of being used as the internal and external cover sheet of the insulated panel. The results indicate that the overall heat transfer coefficient, U (W/m2K) value of the composite reinforced with 10%wt. of fibre at 0o orientation (G10E) offers the lowest U value of 0.386950W/m2K and 0.196680W/m2K for 50mm and 100mm insulation thicknesses, respectively. This further shows their potential of being used as internal and external cover of insulation materials which may prolong the ageing period of insulation and also the shelf life of fresh raw fruits. Keywords: composite sheets, refrigerated vehicle, energy conservation, fossil fuel, climate change

Heat Transfer Reduction Across the Walls of Refrigerated Van Trailers by the Application of Phase Change Material

The purpose of this thesis is to present the results obtained by incorporating phase change materials (PCMs) into the conventional insulated walls of commercial refrigerated van trailers (herein referred to as "refrigerated trucks"). The idea was to apply a building insulation technology (inclusion of PCMs) that was developed previously, at the University of Kansas, in the walls of refrigerated trucks. Although the technology had been applied to buildings, the concept is a novel one within the automotive industry. Although transportation experiences more dynamic challenges compared to its building counterpart, this analysis can open an interesting window for an innovative solution to an area of energy used in the transportation sector. In this research endeavor, two similar van trailer simulators were constructed and used to test the proposed technology under stationary environmental conditions. Both simulators were outfitted with the same number of measurement devices in the exact same locations. The technology was tested in similar days in terms of temperature and solar insolation. The relevant variables that were monitored were the heat flux across the walls of the simulators and temperatures, including surface and indoor air temperatures. Other relevant data, such as weather parameters (e.g., insolation) were also measured and recorded. The primary observation was how the peak heat flux and the total heat flow responded for the two simulators. The results obtained suggested that the van trailer simulator outfitted with PCMs had lower peak heat transfer rates by approximately 42.4% and total heat flow over a period of time one day by as much as 27.7%. Month-long results suggested that the reductions produced by the proposed technology were 43.8% for peak heat transfer rate and 26.3% for total heat transfer. The refrigeration units that cool the insides of refrigerated trucks do so by burning fossil fuel, usually diesel. Any decrease in the refrigeration load requirements would eventually result in lower fuel consumption. The reduction in heat transfer rate (i.e., peak load) would assist in reducing the size of the cooling equipment, which could also result in cost savings

Phase Change Materials (PCMs): an Opportunity for Energy Saving in the Cold Chain

Mantenere la qualità e la sicurezza degli alimenti lungo tutta la catena del freddo, rappresenta una delle principali sfide per il settore della refrigerazione. Allo stesso tempo, garantire una temperatura costante lungo la filiera del freddo determina un elevato consumo energetico, comportando elevate emissioni di CO2 in atmosfera. A tale proposito l’attività di ricerca è stata finalizzata alla sperimentazione di diverse possibilità di utilizzo dei materiali in passaggio di fase (PCMs), per ottimizzare le prestazioni energetiche dei sistemi di trasporto e stoccaggio refrigerati. Inizialmente l’attività di ricerca si è focalizzata sull’applicazione del PCM nell’involucro di un container refrigerato, al fine di ridurre e sfasare temporalmente il carico di raffreddamento. Tale tecnologia è stata valutata mediante approccio numerico e sperimentale, consentendo pertanto di validare il modello numerico. In un secondo momento, sono stati valutati i benefici energetici legati ad uno scambiatore di calore contenete PCM posizionato in prossimità dell’evaporatore di una cella frigorifera. Gli obiettivi di tale attività sono stati quelli di ridurre il consumo di energia elettrica in condizioni di regime stazionario ed il tasso di incremento della temperatura all’interno del vano in caso di black-out. Inoltre, al fine di aiutare le compagnie di trasporto refrigerato ad implementare le giuste misure di efficienza per la produzione del freddo è stato prodotto un tool di calcolo. Infine, l’attività di ricerca è stata focalizzata sull’applicazione del PCM nelle pareti interne del vano refrigerato di una cella frigorifera, allo scopo di ridurre il picco di temperatura dell’aria ed il consumo di energia elettrica durante differenti aperture della porta. Complessivamente i risultati ottenuti hanno evidenziato come l’applicazione dei PCM nelle diverse tecnologie refrigerate, determina una interessante riduzione dei consumi di energia elettrica e delle emissioni di CO2 in atmosfera.Ensuring both food quality and safety to the global population through the cold chain is the major challenge for the refrigeration sector. At the same time guaranteeing, a constant temperature throughout the entire cold chain determines a high-energy consumption and related CO2 emissions into the atmosphere. Therefore, in this dissertation, different approaches aimed at improving refrigerated storage and transport systems performance by Phase Change Materials (PCMs) application have been investigated. The first study have focused on the application of PCM layer to the external side of a refrigerated container envelope, in order to reduce and shift the cooling load in comparison with a conventional enclosure. To that end, the proposed technology was evaluated using a numerical and experimental design study. The calculation results were compared with the experimental values in order to validate the mathematical model. In the field of refrigerated storage, the application of a PCM air heat exchanger near the evaporator of a cold room was experimentally investigated. The study purposes were to reduce the cooling energy consumption during normal operating conditions and the rate of temperature increase throughout the course of a power failure event. Moreover, in order to help refrigerated transport companies to define and implement the right efficiency measures for cold production by using PCM, a calculation tool has been developed. The final study have focused on the application of PCM layer to the internal compartment walls of a storage cold room, in order to reduce the peak air temperature and energy consumption during different door openings. To that end, the proposed technology was evaluated using an experimental design study. The overall dissertation results highlighted that the PCM addition in the proposed refrigerated technologies can lead to interesting reduction in both energy consumption and related CO2 emissions into the atmosphere

Application of computational fluid dynamics (CFD) in refrigerating chambers: review and perspectives

Trabalho de Conclusão de Curso (Graduação)Advances in the food sector allows people to have at their home a variety of food, but for this to happen, in a country as large as Brazil, sometimes the food needs to be transported a long way in a road by a truck. The cold chain, is used to maintain the quality and increase the shelf life of perishables foods. In order to keep the cold chain, the trucks need to maintain the optimal temperature throughout the transportation. Therefore, the aim of this study was to make a literature review of the use of Computational Fluid Dynamics (CFD) to simulate a refrigerated truck. CFD simulations can be performed to solve many refrigeration problems, such as to analyze the refrigeration unit, inlet and outlet positions, airflow, temperature, cargo design and air curtains. For this purpose, characteristics of the system and consequently the truck must be well known to determine the governing equations, boundary and initial conditions and others parameters needed. Furthermore, studies showed that software FLUENT (ANSYS, Inc.) is the most used in the simulations of refrigerated trucks. Altogether more studies can be made with loaded trucks, different configurations and including more external factors. Studies showed that the maintainance of cold chain still have deficiencies and the use of CFD can help to improve the positioning of inlet, outlet and air courtains, the refrigeration unit and the cargo configuration inside the truck

Derivation of walk-in cooler and freezer Performance Standard equations as they pertain to the ANSI/AHRI Standard 1250 and 1251

Title from PDF of title page, viewed on January 2, 2012VitaIncludes bibliographic references (p. 469-478)Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2012Thesis advisor: Bryan BeckerThe ANSI/AHRI (American National Standard Institute (ANSI)/ Air-Conditioning, Heating, and Refrigeration Institute (AHRI).) Standard 1250/1251 Performance Rating of Walk-In Coolers and Freezers strives to standardize refrigeration equipment performance rating. According to the Standard, refrigeration equipment is tested in a laboratory setting using a defined test method. An existing algorithm is used to calculate the Annual Walk-in Energy Factor (AWEF) which serves as a comparison of energy efficiency between equipment. In this work the algorithm was modified in an attempt to more closely approximate actual refrigeration system operation. To calculate the AWEF, a walk-in box load profile and a ratio of the equipment capacity to the refrigeration load are assumed by the Standard. An extensive literature review of ninety-eight articles was performed to address these assumptions. Information was categorized and analyzed for each load component, including lighting, occupancy, product, infiltration, conduction, and miscellaneous loads. Additional information was collected on refrigeration system design and operation. A model load profile was developed from which a revised AWEF algorithm was obtained. Simulations were performed on four walk-in refrigeration units to validate the revised calculation method. Raw results show improved correlation of compressor runtime, because a specific compressor runtime was targeted, reducing variation between hourly simulations and the 1250 calculation from -29.9% with the AHRI 1250 calculation (Becker et al. 2011) to 1.1% with the Proposed 1250 calculation. AWEF correlation between hourly simulations and the 1250 calculation degraded from -7.4% with the AHRI 1250 calculation (Becker et al. 2011) to 15.9% with the Proposed 1250 calculation. Plotting the results for the AWEF and compressor runtime correlation versus variation in the box load, between the hourly simulation and Proposed 1250 calculation results, revealed an issue with the compressor runtime calculation. At a box load variation of zero, the Proposed 1250 AWEF correlation is improved to -2.4%, and the Proposed 1250 compressor runtime correlation is degraded to -14.6%. If a specific compressor runtime had not been targeted, the AWEF correlation for each simulation set would have been improved. To summarize, the Proposed 1250 equations yield an improved AWEF calculation but do not accurately calculate the corresponding compressor runtime.Introduction -- Review of current work -- Literature review and industry investigation -- Development of proposed model load profile -- Development of proposed AHRI Standard 1250/1251 equations -- EQuest simulations -- Proposed 1250 calculation method discussion -- Conclusion

Energy demand and environmental impacts of food transport refrigeration and energy reduction methods during temperature-controlled distribution

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonThe growing demand for temperature-controlled food distribution is driving the growth of transport refrigeration units (TRUs). The majority of these TRUs are powered using auxiliary diesel engines of less than 19 kW power output. These engines are currently not covered by European regulations on emissions. The emissions from TRUs are instead regulated by the Non-Road Machinery (NRMM) standard which is considered insufficient to adequate control emissions. The reliance of most TRUs on diesel fuel which contributes to both greenhouse gas and particulate emissions has heightened the need for more energy efficient and low carbon alternatives. In this work, a model has been developed to determine the fuel consumption and GHG emission of auxTRUs for the distribution parameters obtained from a survey study conducted as part of research to quantify the energy usage and emissions associated with auxiliary engines for transport refrigeration units in London. Using the model, different alternative technologies have been investigated, which include, cryogenic systems using LN2, cryogenics systems using LCO2, all-electric TRU and hydrogen fuel cell powered TRU. Both production and operation related GHG emissions were considered for the studies. The production related emissions for electricity are lower than the emissions from the production of hydrogen and cryogenic fluids by almost 60%. For this reason, the all-electric TRU was found to be the most suitable alternative to diesel auxTRU in respect to GHG emissions and current infrastructure. The infrastructure for both hydrogen and cryogenic fluids does not exist as yet to support frequent refilling of the transport vehicles. Infiltration of ambient air during door openings has been identified to be a major source of refrigeration load in multi-drop temperature controlled food distribution. Plastic strips curtains are inconvenient to use as they impede loading and unloading. For this reason, even when they are fitted on the vehicle they are not utilised by the drivers. Air curtains can avoid the use of a physical barrier but have not been previously investigated sufficiently for this application. For this reason, extensive experimental and numerical investigations were performed to establish the effectiveness of air curtains to reduce air infiltration into the refrigerated space of distribution vehicles. The air curtain discharge velocity was identified to be an important design parameter for the air curtain. Optimising the discharge velocity and angle has shown to produce an energy savings of 50% in distribution vehicles.RCUK Centre for Sustainable Energy Use in Food Chains (CSEF

Deputy Director

Nonresidential Buildings to be effective on July 1, 2014 now include the following Energy Commission approved and adopted Nonsubstantive errata

Energy and economic analysis of Vacuum Insulation Panels (VIPs) used in non-domestic buildings

The potential savings in space heating energy from the installation of Fumed Silica (FS) and Glass Fibre (GF) Vacuum Insulation Panels (VIPs) were compared to conventional expanded polystyrene (EPS) insulation for three different non-domestic buildings situated in London (UK). A discounted payback period analysis was used to determine the time taken for the capital cost of installing the insulation to be recovered. VIP materials were ranked using cost and density indexes. The methodology of the Payback analysis carried out considered the time dependency of VIP thermal performance, fuel prices and rental income from buildings. These calculations show that VIP insulation reduced the annual space heating energy demand and carbon dioxide (CO2) emissions by approximately 10.2%, 41.3% and 26.7% for a six storey office building, a two floor retail unit building and a four storey office building respectively. FS VIPs had the shortest payback period among the insulation materials studied, ranging from 2.5 years to 17 years, depending upon the rental income of the building. For GF VIPs the calculated payback period was considerably longer and in the case of the typical 4 storey office building studied its cost could not be recovered over the life time of the building. For EPS insulation the calculated payback period was longer than its useful life time for all three buildings. FS VIPs were found to be economically viable for installation onto non-domestic buildings in high rental value locations assuming a lifespan of up to 60 years

NASA technology utilization survey on composite materials

NASA and NASA-funded contractor contributions to the field of composite materials are surveyed. Existing and potential non-aerospace applications of the newer composite materials are emphasized. Economic factors for selection of a composite for a particular application are weight savings, performance (high strength, high elastic modulus, low coefficient of expansion, heat resistance, corrosion resistance,), longer service life, and reduced maintenance. Applications for composites in agriculture, chemical and petrochemical industries, construction, consumer goods, machinery, power generation and distribution, transportation, biomedicine, and safety are presented. With the continuing trend toward further cost reductions, composites warrant consideration in a wide range of non-aerospace applications. Composite materials discussed include filamentary reinforced materials, laminates, multiphase alloys, solid multiphase lubricants, and multiphase ceramics. New processes developed to aid in fabrication of composites are given

Technology applications

A summary of NASA Technology Utilization programs for the period of 1 December 1971 through 31 May 1972 is presented. An abbreviated description of the overall Technology Utilization Applications Program is provided as a background for the specific applications examples. Subjects discussed are in the broad headings of: (1) cancer, (2) cardiovascular disease, (2) medical instrumentation, (4) urinary system disorders, (5) rehabilitation medicine, (6) air and water pollution, (7) housing and urban construction, (8) fire safety, (9) law enforcement and criminalistics, (10) transportation, and (11) mine safety