Life cycle analysis of the environmental impact of different cabinet designs

The design of refrigerated display cabinets greatly affects their subsequent environmental impact. To control this impact, a designer must primarily consider the operating efficiency of a cabinet. However, less account is taken of the materials used to make the cabinet, nor the construction techniques used. These both have a significant effect on the environmental impact of different cabinets outside the use phase of their life cycle. Initial construction impact, remanufacturability and recyclability are all affected. Given the ubiquity of the display cabinet in the retail sector, it is important to assess their lifetime impact in toto. This is particularly so with the increasing implementation of the WEEE directive in member states. Three typical refrigerated display cabinets are examined in this paper, all offering the same function, but manufactured with quite different constructions and materials. The mass of materials in each cabinet was determined experimentally and the methods of assembly examined. The stages in the life of each cabinet were then modelled and life cycle analyses performed. To compare the efficiency of the cabinets in terms of their environmental impact, the Eco Indicator Points/litre of refrigerated space/day were determined in each case. When combined with the energy performance (kWh/litre/day) this provides a good measure of the overall environmental impact of a cabinet and a way of choosing between different models that nominally provide the same refrigeration function. Different end of life scenarios, and improvements in the choice of materials, were also investigated depending on the type of construction

Effect of Night Blinds on Open Integral Display Cabinets

The impact of night blinds on the product temperature performance and electrical energy consumption of an integral open multi-deck cabinet is investigated in this paper. The cabinet was tested at various environmental conditions to establish the impact of ambient temperature on the effectiveness of the blind in reducing the energy consumption of the cabinet during night-time operation. The cabinet was tested over a range of temperatures between 20 °C and 35 °C at a constant moisture content. The results indicate that the use of night blinds could produce energy savings of between 10% and 22% calculated on the basis of a 24 hour period of operation with the blind lowered for 12 hours out of the 24 hours. These energy savings lead to pay-back periods of between 2 and 4 years. The savings reduced with increasing ambient temperature due to the increase in the impact of infiltration and conduction across the blind at higher temperatures

Potential for Solar Energy in Food Manufacturing, Distribution and Retail

The overall aim of the study was to assess the potential for increasing the use of solar energy in the food sector. For comparative purposes the study also included an assessment of the benefits that could arise from the use of other renewable energy sources, and the potential for more effective use of energy in food retail and distribution. Specific objectives were to: i) establish the current state of the art in relevant available solar technology; ii) identify the barriers for the adoption of solar technology; iii) assess the potential for solar energy capture; iv) appraise the potential of alternative relevant technologies for providing renewable energy; v) assess the benefits from energy saving technologies; vi) compare the alternative strategies for the next 5-10 years and vii) Consider the merits of specific research programmes on solar energy and energy conservation in the food sector. To obtain the views of the main stakeholders in the relevant food and energy sectors on the opportunities and barriers to the adoption of solar energy and other renewable energy technologies by the food industry, personal interviews and structured questionnaires tailored to the main stakeholders (supermarkets, consultants for supermarket design; energy and equipment suppliers) were used. The main findings from the questionnaires and interviews are: - Key personnel in supermarkets and engineers involved in the design of supermarkets are aware of the potential contribution of renewable energy technologies and other energy conservation measures to energy conservation and environmental impact reduction in the food industry. A number of supermarket chains have implemented such technologies at pilot scale to gain operating experience, and more importantly, for marketing reasons, to gain competitive advantage through a green image. - From installations to date in the UK the most notable are a 600 kW wind turbine at a Sainsbury's distribution centre in East Kilbride and a 60 kWp photovoltaic array at a Tesco store in Swansea. - The main barrier to the application of renewable energy technologies in the food sector is the capital cost. Even though significant progress has been made towards the improvement of the energy conversion efficiencies of photovoltaic technologies (PVs) and reduction in their cost, payback periods are still far too long, for them to become attractive to the food industry. - Wind energy can be more attractive than PVs in areas of high wind speed. Apart from relatively high cost, the main barrier to the wide application of wind turbines for local power generation is planning restrictions. This technology is more attractive for application in food distribution centres that are normally located outside build-up areas where planning restrictions can be less severe than in urban areas. In these applications it is likely that preference will be for large wind turbines of more than 1.0 MW power generation capacity as the cost of generation per unit power reduces with the size of the turbine

Influence of Operation Parameters on Thermohydraulic Performance of Supercritical CO2 in a Printed Circuit Heat Exchanger

Figures & Data - https://www.tandfonline.com/doi/figure/10.1080/01457632.2024.2384157?scroll=top&needAccess=trueThe performance of recuperative printed circuit heat exchangers is critical in supercritical CO2 (sCO2) power generation applications. This article presents a three-dimensional numerical model of sCO2 flowing in a printed circuit heat exchanger and investigates its thermohydraulic performance under different operation conditions. The simulations employ the standard k-ε turbulent model, and consider entrance effects, conjugate heat transfer, real gas thermophysical properties and buoyancy effects. The heat exchanger operation parameters cover mass flux from 254.6 to 1273.2 kg/m2s, inlet temperature 50–150 °C and outlet pressure 100–250 bar on the cold side, and 300–500 °C and 75–150 bar on the hot side. Results show that increasing CO2 mass flux leads to a significantly increased heat transfer coefficient, a slight increase in temperature difference between the hot and cold CO2, as well as larger pressure drop and lower friction factor on both sides. Increasing the cold CO2 pressure, decreasing the cold CO2 temperature, and increasing the hot CO2 temperature result in a higher heat transfer rate of the heat exchanger. Increasing the CO2 temperature on each side causes increased pressure drops on both sides. Increasing the CO2 pressure on each side reduces the pressure drop on each side.(i) The Engineering and Physical Sciences Research Council (EPSRC) of the UK under research grants EP/P004636/1—OPTEMIN, and EP/V001795/1—SCOTWOHR; (ii) the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 680599—I-ThERM and Grant Agreement No. 101022831—CO2OLHEAT

Experimental study on a small-scale R245fa organic Rankine cycle system for low-grade thermal energy recovery

This work conducted an experimental investigation of a small-scale organic Rankine cycle (ORC) system at designed operating and control conditions for low-grade thermal energy recovery application. In the ORC system, R245fa was selected as working fluid while a turboexpander (turbine) with a high speed and permanent magnet synchronous electricity generator was installed to produce electric power and two-plate type heat exchangers were designed as an evaporator and condenser. The effects of condenser cooling water temperatures and R245fa superheat at the turbine inlet on the system performance were measured and analyzed. Practically, to ensure safe operation of the ORC expander, the R245fa superheat at the expander inlet is controlled to remain constant. The experimental results showed that at constant heat source parameters (temperature and flow rate), the turboexpander power output and cycle efficiency increased with lower cooling water temperatures. Under the specified test condition ranges, the maximum turboexpander power generation could achieve 5.405 kW when the cooling water temperature and the pressure ratio were set at 23.0°C and 7.3 respectively. On the other hand, at certain cooling water temperatures, the superheat at the expander inlet exerted a negative impact on the turboexpander and system performances when the evaporating pressure was kept constant. Ultimately, the superheat was found to be an important control parameter to ensure efficient and safe system operation

Modelling of plate heat exchangers and their associated CO2 trancritical power generation system

Globally, there is no shortage of low-grade waste and renewable heat sources that can be converted into electricity and useful heat using applicable thermodynamic power cycles and appropriate working fluids. As a natural working fluid, CO2 is a promising candidate for application in low-grade power generation systems but require optimised design and evaluation. Since CO2 working fluid has a low critical temperature (31.1⁰C) and high critical pressure (73.8 bar), a CO2 low-grade power generation system will most likely undergo supercritical Rankine (T-CO2) cycles. A T-CO2 system normally consists of a CO2 supercritical gas heater, expander, recuperator, condenser and liquid pump with the CO2 gas heater being a crucial component in determining system thermal and exergy efficiencies. In this paper, the models of a thermal oil-CO2 plate gas heater has been developed and validated with measurements of a 5kWe T-CO2 system test rig. The model is then integrated with other system component models to establish the system model. The system model can be used to evaluate and compare system performances at different operating conditions, including variable CO2 gas heater pressures and heat sink parameters, thereby optimising system operations.The authors would like to acknowledge the support received from GEA Searle and Research Councils UK (RCUK) for this research project

Experimental Study of a Light Commercial Refrigeration System Operating Under Frosting Conditions

Investigation the effect of frost formation on a light commercial refrigeration syste

Advanced spreadsheet based methodology for the dynamic thermal modelling of buildings

Thermal analysis of buildings was carried out using simplified design tools, prior to the widespread use of computers. Since the early 1980's, the rapid growth of computational power has lead to the introduction of many building dynamic thermal simulation software programs. The accurate performance of many of these programs has lead to the view that manual calculation methods should only be used as indicative design tools. The CIBSE admittance method is based on the fundamentals of building heat transfer, its calculations procedures being simplified for use on hand held calculators. Manual calculation methods must be developed for use on more powerful calculators, if greater accuracy is required. Such calculators are available in the form of computer spreadsheet programs. The computational power of the computer spreadsheet program, combined with suitable mathematical thermal modelling techniques, has thus far, remained unexploited. This thesis describes the development of a powerful manual thermal design method, for application on a computer spreadsheet program. All the modes of building heat transfer are accurately modelled. Free-running or plant-controlled spaces can be simulated. In the case of a single zone, the accuracy of the new manual dynamic thermal model is comparable with commercially available software programs. The level of mathematical modelling complexity is limited only by computer power and user ability. The Iterative Frequency Domain Method (IFDM) and the Adiabatic Iterative Frequency Domain Method (AIFDM) are alternative mathematical simulation techniques developed to form the core of the Thermal Analysis Design Method. In the IFDM and AIFDM, the frequency domain and numerical iteration techniques have been integrated to produce a thermal simulation method that can model all non-linear heat transfer processes. A more accurate formulation of sol-air temperature, a window sol-air temperature and an accurate reduced internal long-wave radiant exchange model is a sample of further innovations in the thesis. Many of the developments described in the thesis, although designed for the computer spreadsheet environment, may also be employed to enhance the performance of some of the current dynamic thermal models of buildings.EThOS - Electronic Theses Online ServiceDublin Institute of TechnologyGBUnited Kingdo