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冷链及其物流

www.bysj580.com / 2023-07-30
冷链及其物流
      作者:Jean-Paul Rodriguez 博士 和 Theo Notteboom 博士
1.概观
    虽然全球化使世界小得多的地区之间的相对距离,这些地区的物理分离仍是一个非常重要的现实。更大的物理分离,更可能的货运可以在一个复杂的运输业务涉及损坏。有些货物可能会被损坏受到冲击,而有些人可以不让的温度变化而损坏。对于易腐物品,特别是食品标示的商品的范围,他们的质量下降,因为他们保持率可大多较低温度下减轻化学反应随着时间的推移。这需要时间的协调,有效地移动货物,每延迟可以产生消极后果,特别是如果这是易腐货物。以确保货物不会成为损坏或破坏整个过程中,在制药,医疗,食品等行业的企业正越来越多地依靠冷链技术。
    冷链是指温度敏感产品的运输,以及通过热和冷藏包装方法的供应链和后勤规划,以保护这些货物的完整性。
专业化,导致许多企业不仅依靠重要的航运服务提供商,如美国联合包裹服务公司(UPS)和联邦快递,但也更集中的行业专家已经开发出一个利基周围的温度敏感产品的运输后勤专长的潜力,以了解当地的规则,海关和环境条件,以及估计的长度和时间的分布路线,使它们在全球贸易中的重要因素。因此,物流业经历了几个潜在的利基市场,在全球商品链中的冷链运输的专业化和分割的增长水平。整个分销业的新的细分市场一直很活跃,以优势的双重发展空间扩展的供应链全球化和各种货物流通的重要支持。从经济发展的角度,的冷链使许多发展中国家采取易腐产品在全球市场的一部分。从地理的角度,冷链有下列影响:
•全球。专业化的农业功能,允许对温度敏感的食品运送到遥远的市场。使疫苗和其他药品或生物制品的分销。
•区域。可以支持的功能和规模经济,如专门的实验室,专业化的。
•地方。及时分发到最终消费者,即杂货店和餐馆。
2.冷链物流的兴起
    虽然全球商品链是相当现代的扩张,在交通运输行业的冷藏温度敏感货物运动是一种实践,可以追溯到1797时,英国渔民使用天然冰,以保护鱼类桩。这个过程也被看作从农村到城市的消费市场,即乳制品食品运动在19世纪末期。冷库也是一个殖民国家和他们的殖民地之间的食品贸易的重要组成部分。例如,在19世纪70年代末和1880年代初期,法国开始接收来自南美洲的大型冷冻肉和羊肉尸体出货量,而英国进口冷冻牛肉从澳大利亚和新西兰的猪肉及其他肉。到1910年,60吨冻肉被带到大不列颠独自。被美国食品公司在1903年推出的第一冷藏船的香蕉贸易。这使香蕉从异国情调的水果,有一个小市场,因为它抵达太成熟的市场,为世界上最消耗的水果之一。
    温度控制的药品和医疗用品的运动是比冷藏或冷冻食品的运输更加现代化的交通选项。 20世纪50年代以来,后勤第三方公司开始出现和研究所的新方法,成功地运送这些全球性的商品。它们的出现之前,冷链流程大多在内部管理。在美国,食品和药物管理局限制和问责措施,在稳定冷链煽动许多这些公司的专业快递,而不是依靠他们的供应链设施彻底检修。因此诞生了一个专门的行业。在冷链保存昂贵的疫苗和医疗用品的价值才开始被认可时,这些后勤供应开始出现。作为意识开始恢复增长,也为高效的冷链管理的需要。
    对冷链的依赖将继续受到重视。比如制药行业,例如,在很大程度上依赖于药物试验,生产和运动控制和无与伦比的出货量转移。一个的沿冷链移动的医药产品大部分是在实验或发展阶段。临床研究和试验,是一个业内人士认为,花费数百万美元的重要组成部分,但也经历了80%左右的失败率。据医疗配送管理协会,接近200亿美元的药品流通,约10%是对温度敏感的药物。负责运送近20亿美元的投资,这使得冷链。如果这些货物应该遇到任何意外曝光变温度水平,他们成为无效或病人的甚至是有害的运行风险。
    在装运食品的温度控制是继续与国际贸易的必要性上升的行业的一个组成部分。越来越多的国家作为重点围绕食品出口的经济和生产的生产,需要长时间保持新鲜这些产品已获得重要性。提高收入水平创造改变,其中包括越来越多的新鲜水果和价值较高的食品,如肉类和鱼类食欲的饮食。具有较高的社会经济地位和更多的经济手段的人更容易消​​费的蔬菜和水果,尤其是新鲜的,不但数量较高,但也更多样化。随着购买力的消费者已经成为健康饮食的斤斤计较,因此,生产商和零售商的异国情调的新鲜水果,来自世界各地的数组回应。
    任何杂货店世界各地的主要是来自南非的柑橘,来自新西兰的苹果,来自哥斯达黎加的香蕉,芦笋可能携带来自墨西哥。因此,冷链产业已经成为这些商品链服务。 2002年,估计有1200亿美元的食品价值400,000(冷藏船)冷藏集装箱船队运输。仅此一项,美国进口水果和蔬菜的约30%和20%的食品出口,可以考虑易腐烂。这种食品的无与伦比的质量和安全往往是理所当然的,尽管出售食品的能力背后的主要原因。冷链供应长时间和消除疑虑的食品质量保持食物新鲜的功能。在所有与它有关的供应链,冷链物流的青睐,因为保持温度的完整性,所有的过程控制需要更高层次的更高的集成度。它甚至可能煽动第三方物流供应商的供应链获得时间和其他性能因素是最重要的元素,甚至养殖。这可能涉及收购农产品农场(如柑橘),以确保供电的可靠性。
3.提供受控环境温度
    依靠冷链行业的成功归结知道如何船舶与航运的情况下适应温度控制产品。不同的产品需要不同的温度级维修,以确保其在整个旅行过程中的完整性。例如,最常见的温度标准是“香蕉”(13℃),(2℃)的“寒意”,“冻结”(-18℃)和“速冻”(-29℃)。住在此温度下沿供应链和装运易腐,它使以确保最佳的货架寿命的完整性是至关重要的。任何分歧可能会导致不可撤销的和昂贵的损害;产品可以简单地失去任何市场或有用的价值。
    能够确保货物的温度范围内保持一个较长时期的主要类型的容器,使用和制冷方法。过境时间等因素,装运的大小和经历的环境或外界温度是重要的决定需要什么样的包装类型。它们的范围可以从小型的需要干冰或凝胶包,滚动容器,53页脚它有自身的供电制冷机组的冷藏保温箱。冷链技术主要涉及:
•干冰。固态二氧化碳,大约是-80℃,是能够保持长时间的冷冻装运。它特别用于药品,危险品和食品的运输。干冰不会融化,相反,它升华时,它在与空气接触。
•凝胶包。制药和药用出货量大股归类为冷冻产品,这意味着他们必须在2至8°C的温度范围内的存储提供这种温度的常用方法是使用凝胶包,或包包含相变物质,可以从固体到液体,反之亦然,以控制环境。根据对航运的要求,这些包可以开始在冷冻或冷藏的状态。沿过境过程中,他们融化的液体,而在同一时间捕捉逃脱的能源和维持内部温度。
•共晶板。原理是相似的凝胶包。相反,板充满液体,可多次重复使用。
•液态氮。一个特别寒冷的物质,约-196°,用来保持了相当长的时间内冻结的包。主要用于运输货物的组织和器官,如生物。它被视为有害物质运输的目的。
•被子。绝缘货运以上或周围放置充当缓冲温度变化,并保持温度相对恒定的作品。因此,冷冻货运将维持较长一段时间内冻结,往往足够长的时间没有理由使用更昂贵的制冷设备。被子也可用于室温保持在温度敏感的货物,而外部条件可以显着变化(例如,在夏季或冬季)。
•冷藏船。温度控制的容器,它可以是一辆面包车,小货车,半或ISO标准集装箱的通用名称。这些容器,绝缘,是专门设计,以便保持一个附加的和独立的制冷设备厂的温度控制空气流通。一词越来越多地应用到冷藏四十英尺国际标准集装箱。
易腐或温度敏感的物品进行冷藏集装箱(称为“冷藏”),该帐户的份额越来越大,被世界各地的运输冷藏货物。而在1980年,集装箱海运冷藏运输能力的33%,这一比例迅速攀升到47%,在1990年,68%在2000年和2010年的90%。 2009年被用来冷藏约1.69万个标准货柜单位。所有冷藏漆成白色,增加了反照率(份额的入射光被反射;高反照率意味着更少的表面吸收的太阳能)占主导地位的40个高立方体页脚的大小(45R1的规模和类型的代码)。例如低反照率容器可以有其内部的温度升高到50°C,当外界温度达到25°C,而在一个阳光灿烂的日子高反照率容器在相同条件下其内部的温度升高到只有38°C间。
    制冷机组的冷藏要求在运输过程中和在集装箱堆场的电力来源。定期货柜船有10%至20%的调整,进行冷藏,一些船只有高达25%的插槽致力于其插槽。重要的是要强调,制冷机组的设计,保持前缀范围内的温度,而不是它冷却下来。这意味着必须把装运前被装载到冷藏,这就需要专门的仓储和装载/卸载设施所需的温度。新一代的冷藏来上网,配备有一个有效的温度监测和关闭不必要的冷却装置,当传感器阵列。这使以提高温度控制的可靠性,以及延长冷藏自治。
    联运冷藏增长已越来越多地需要运输码头,港口,专用堆场冷藏。总的终端能力的1%至5%,但与此帐户可以是较高的转运枢纽。堆叠的要求仅仅涉及到相邻的电源插座,但任务是更多的劳动力密集每个容器必须插入和拔出手动和温度进行定期监测,因为它是码头运营商的责任,以确保冷藏保持其在预设范围内的温度。这也可能禁止使用高架龙门吊暗示冷藏堆放区,可以通过不同的设备提供服务。即使冷藏涉及终端成本较高,他们是非常有利可图的,因为他们运输高价值的商品。
4.冷链的设置和组织
    移动整个供应链的货物,没有受到任何挫折或温度异常,需要建立一个全面的物流过程中保持货物的完整性。这个过程涉及几个阶段,从编制出货量最终核实的交货点的货物的完整性:
•装运准备。当温度敏感的产品正在移动,先评估其特点是至关重要的。一个关键的问题是关于货物的温度调节,这应该是已经在所需的温度。冷链设备的设计通常以保持温度恒定,但不带运到这个温度,所以他们将无法充分履行职责,如果货物不准备和条件。其他问题包括货物的目的地,并为这些地区,例如,如果货物运输沿线将暴露极端寒冷或炎热的天气条件。
•模式的选择。几个关键因素发挥如何将迁往装运。原产地和最终目的地(通常包括一套中介位置),大小和货物的重量,所需的外部环境温度和产品的任何时间限制,所有的效果可用的运输选项之间的距离。短距离可以处理与一辆面包车或卡车,而可能需要一个较长的行程飞机或集装箱船。
•自定义程序。如果货物越过边界,海关手续变得非常重要,因为冷链产品往往是时间敏感和更受比普通货运(如药品和生物样品)检验。这个任务的难度不同而不同国家(或经济集团)和网关上,因为有程序和延迟变化。
•“最后一公里”。最后一个阶段是到其目的地的货物,物流常常被称为“最后一公里”的实际交付。重点考虑的不仅是目标,但时间安排最终交付的关注。卡车和货车,交通这个阶段的主要模式,必须满足必要的规格,传输冷链装运。同样重要的是最终转移货物的仓储设施,有违反诚信的潜力。
•完整性和质量保证。已交付货物后,必须在任何温度记录装置或已知的温度异常记录,并作出已知。这是后勤的过程中,建立信任和问责的一步,尤其是如果发生损坏的货物的赔偿责任。如果确实发生问题或异常现象危及货物,必须作出努力,查明来源,并找到纠正措施。
    因此,冷链的设置和操作,是依赖于有关的供应链,因为每个单元进行货物有不同的需求,负载完整性和运输完整性的要求。
5.食品运输
    有香蕉会计与世界上最重要的食品冷链运输的所有海运冷藏贸易的20%的商品运输食品的各种方法。所有的陆地,海上和空中模式有不同的结构,为保持食物新鲜整个运输链。在包装,水果和蔬菜的涂层,生物工程(控制成熟),减少食品变质的其他技术创新有帮助托运人扩大易腐产品的范围。对于食品,如水果和蔬菜,时间对他们的货架寿命,因此有一批货物可能产生的潜在收入的直接影响。随之而来,新的传输技术已获准在更长的距离装运易腐产品。例如,改善道路和沿非洲海岸的联运连接减少食品的运输时间从10天至4天到欧洲市场。
    某些国内或跨国供应链可能只需要一个运输模式,但多次地面运输交通工具的组合中的一环。这使得换乘冷链的关键。联运的出货量通常使用20或40页脚冷藏集装箱的能力,最多可容纳26吨粮食。货柜装卸周期短,不容易遇到损坏。目前,在这些容器中的环境是通过插入到船或卡车上的一台发电机或电源电子控制,但早期的食品出货量将循环空气保持干燥或潮湿的冰商店食品冷藏。冷链物流的效率允许的冷藏设施的整合。
    移动冰制冷,允许更大的旅行和距离,大大增加了全球粮食市场的规模,使许多发展中国家,捕捉新的机遇。运送食品的另一种有效的模式是空中旅行。虽然这是一个旅游的首选形式高度易腐和贵重物品,由于其移动更长的距离,更快的能力,但它确实缺乏对环境控制和传输的地面和海上运输方便。另外,在飞行过程中的货物存放在15℃ - 20°C的环境,但接近80%的时间,包被暴露在外部的天气,而等待被加载到飞机或移动和机场。这是困扰考虑食物的价值和背后的质量和新鲜度的重视。为了使这种形式的粮食运输的经验,在市场用户的增长,更不妥协的策略和法规将要拥抱和制定。
    粮食运输是一个已经完全适应冷链,尽管与航空运输的问题,可以被认为是最有活力,特别是因为大部分的食品临时运输温度变化的耐受性有一个更好的产业。因此,小错误可以加剧没有关注不可逆转的损害。例如,为运输生产中,每隔一小时延迟预冷的出货量,同等之一保质期一天的损失,必须占。冷藏集装箱的使用,特别是帮助,因为他们占所有运输冷藏货物在世界上超过50%。源负载是一个重要因素,冷链产品的货架寿命延长,因为它被装在冷藏直接在生产地点,无需额外处理。例如,源加载到冷藏可以扩大冰鲜肉类的保质期由25天左右,从传统的方法(从30-35天55-60天),从而大大扩大了产品的市场潜力。
    温度控制交通的效率和可靠性已经达到了一个点,这使得食品行业采取全球季节性变化的优势,这意味着,在冬季的南半球易腐货物出口到北半球,而相反的贸易,一般规模较小在暑假期间举行。如智利等国已大大得益于此,在冬季主要服务北美市场,而且还与几个利基市场,如酒已开发出一种积极的农​​业和粮食转化产业。类似的问题涉及一些已经开发出一种新鲜农产品和花卉产业,餐饮业在欧洲市场的非洲国家,如肯尼亚。快餐业是冷链​​物流的活跃用户,每一个插座都可以被视为一个工厂,几十个工人的时间表和班次,库存管理和组件的供应链(其中许多是对温度敏感),这是生产质量控制和大批量产品的装配生产线。

The Cold Chain and its Logistics
                     Authors: Dr. Jean-Paul Rodriguez and Dr. Theo Notteboom
1. Overview
While Globalization has made the relative distance between regions of the world much smaller, the physical separation of these same regions is still a very important reality. The greater the physical separation, the more likely freight can be damaged in one of the complex transport operations involved. Some goods can be damaged by shocks while others can be damaged by undue temperature variations. For a range of goods labeled as perishables, particularly food, their quality degrades with time since they maintain chemical reactions which rate can be mostly mitigated with lower temperatures. It takes time and coordination to efficiently move a shipment and every delay can have negative consequences, notably if this cargo is perishable. To ensure that cargo does not become damaged or compromised throughout this process, businesses in the pharmaceutical, medical and food industries are increasingly relying on the cold chain technology.
The cold chain refers to the transportation of temperature sensitive products along a supply chain through thermal and refrigerated packaging methods and the logistical planning to protect the integrity of these shipments.
Specialization has led many companies to not only rely on major shipping service providers such as the United Parcel Service (UPS) and FEDEX, but also more focused industry specialists that have developed a niche logistical expertise around the shipping of temperature sensitive products. The potential to understand local rules, customs and environmental conditions as well as an estimation of the length and time of a distribution route make them an important factor in global trade. As a result, the logistics industry is experiencing a growing level of specialization and segmentation of cold chain shipping in several potential niche markets within global commodity chains. Whole new segments of the distribution industry have been very active in taking advantage of the dual development of the spatial extension of supply chains supported by globalization and the significant variety of goods in circulation. From an economic development perspective, the cold chain enables many developing countries to take part in the global perishable products market. From a geographical perspective, the cold chain has the following impacts:
Global. Specialization of agricultural functions permitting the transport of temperature sensitive food products to distant markets. Enables the distribution of vaccines and other pharmaceutical or biological products.
Regional. Can support the specialization of functions and economies of scale, such as specialized laboratories.
Local. Timely distribution to the final consumer, namely grocery stores and restaurants.
2. Emergence of Cold Chain Logistics
While global commodity chains are fairly modern expansions in the transportation industry, the refrigerated movement of temperature sensitive goods is a practice that dates back to 1797 when British fishermen used natural ice to preserve their fish stock piles. This process was also seen in the late 1800s for the movement of food from rural areas to urban consumption markets, namely dairy products. Cold storage was also a key component of food trade between colonial powers and their colonies. For example, in the late 1870s and early 1880s, France was starting to receive large shipments of frozen meat and mutton carcasses from South America, while Great Britain imported frozen beef from Australia and pork and other meat from New Zealand. By 1910, 600,000 tons of frozen meat was being brought into Great Britain alone. The first reefer ship for the banana trade was introduced in 1903 by the United Food Company. This enabled the banana to move from an exotic fruit that had a small market because it arrived in markets too ripe, to one of the world's most consumed fruit.
The temperature controlled movement of pharmaceuticals and medical supplies is a much more modern transit option than the shipping of refrigerated or frozen food. Since the 1950s, logistical third party companies began to emerge and institute new methods for successfully transporting these global commodities. Before their emergence, cold chain processes were mostly managed in house by the manufacturer. In the United States, Food and Drug Administration restrictions and accountability measures over the stability of the cold chain incited many of these companies to rely on specialty couriers rather than completely overhauling their supply chain facilities. A specialized industry was thus born. The value of the cold chain in the preservation of expensive vaccines and medical supplies was only beginning to be recognized when these logistical providers started to appear. As awareness began to grow, so did the need for efficient management of the cold chain.
The reliance on the cold chain continues to gain importance. Within the pharmaceutical industry for instance, the testing, production and movement of drugs relies heavily on controlled and uncompromised transfer of shipments. A large portion of the pharmaceutical products that move along the cold chain are in the experiment or developmental phase. Clinical research and trials is a major part of the industry that costs millions of dollars, but one that also experiences a failure rate of around 80%. According to the Healthcare Distribution Management Association, of the close to 200 billion dollars in pharmaceutical distribution, about 10% are drugs that are temperature sensitive. This makes the cold chain responsible for transporting a near 20 billion dollar investment. If these shipments should experience any unanticipated exposure to variant temperature levels, they run the risk of becoming ineffective or even harmful to patients.
Temperature control in the shipment of foodstuffs is a component of the industry that has continued to rise in necessity with international trade. As a growing number of countries focus their export economy around food and produce production, the need to keep these products fresh for extended periods of time has gained in importance. Increasing income levels create a change in diet with amongst others a growing appetite for fresh fruit and higher value foodstuffs such as meat and fish. Persons with higher socioeconomic status and with more economic means are more likely to consume vegetables and fruit, particularly fresh, not only in higher quantities but also in greater variety. Consumers with increasing purchase power have become preoccupied with healthy eating, therefore producers and retailers have responded with an array of exotic fresh fruits originating from around the world.
Any major grocery store around the world is likely to carry tangerines from South Africa, apples from New Zealand, bananas from Costa Rica and asparagus from Mexico. Thus, a cold chain industry has emerged to service these commodity chains. In 2002, an estimated 1200 billion dollars' worth of food was transported by a fleet of 400,000 refrigerated containers (Reefers). Alone, the United States imports about 30% of its fruits and vegetables and 20% of its food exports can be considered perishables. The uncompromised quality and safety of this food is often taken for granted, despite being the main reason behind the ability to sell the food. The cold chain serves the function of keeping food fresh for extended periods and eliminating doubts over the quality of the food products. In all the supply chains it is concerned with, cold chain logistics favor higher levels of integration since maintaining temperature integrity requires a higher level of control of all the processes involved. It may even incite third party logistics providers to acquire elements of the supply chain where time and other performance factors are the most important, even farming. This may involve the acquisition of produce farms (e.g. oranges) to insure supply reliability.
3. Providing Temperature Controlled Environments
The success of industries that rely on the cold chain comes down to knowing how to ship a product with temperature control adapted to the shipping circumstances. Different products require different temperature level maintenance to ensure their integrity throughout the travel process. For instance, the most common temperature standards are  "banana" (13 °C), "chill" (2 °C), "frozen"  (-18 °C) and "deep frozen" (-29 °C). Staying within this temperature is vital to the integrity of a shipment along the supply chain and for perishables it enables to insure and optimal shelf life. Any divergence can result in irrevocable and expensive damage; a product can simply lose any market or useful value.
Being able to ensure that a shipment will remain within a temperature range for an extended period of time comes down largely to the type of container that is used and the refrigeration method. Factors such as duration of transit, the size of the shipment and the ambient or outside temperatures experienced are important in deciding what type of packaging is required. They can range from small insulated boxes that require dry ice or gel packs, rolling containers, to a 53 footer reefer which has its own powered refrigeration unit. The major cold chain technologies involve:
Dry ice. Solid carbon dioxide, is about -80°C and is capable of keeping a shipment frozen for an extended period of time. It is particularly used for the shipping of pharmaceuticals, dangerous goods and foodstuffs. Dry ice does not melt, instead it sublimates when it comes in contact with air.
Gel packs. Large shares of pharmaceutical and medicinal shipments are classified as chilled products, which means they must be stored in a temperature range between 2 and 8°C. The common method to provide this temperature is to use gel packs, or packages that contain phase changing substances that can go from solid to liquid and vice versa to control an environment. Depending on the shipping requirements, these packs can either start off in a frozen or refrigerated state. Along the transit process they melt to liquids, while at the same time capturing escaping energy and maintaining an internal temperature.
Eutectic plates. The principle is similar to gel packs. Instead, plates are filled with a liquid and can be reused many times.
Liquid nitrogen. An especially cold substance, of about -196°C, used to keep packages frozen over a long period of time. Mainly used to transport biological cargo such as tissues and organs. It is considered as an hazardous substance for the purpose of transportation.
Quilts. Insulated pieces that are placed over or around freight to act as buffer in temperature variations and to maintain the temperature relatively constant. Thus, frozen freight will remain frozen for a longer time period, often long enough not to justify the usage of more expensive refrigeration devices. Quilts can also be used to keep temperature sensitive freight at room temperature while outside conditions can substantially vary (e.g. during the summer or the winter).
Reefers. Generic name for a temperature controlled container, which can be a van, small truck, a semi or a standard ISO container. These containers, which are insulated, are specially designed to allow temperature controlled air circulation maintained by an attached and independent refrigeration plant. The term increasingly apply to refrigerated forty foot ISO containers.
Perishable or temperature sensitive items are carried in refrigerated containers (called "reefers"), that account for a growing share of the refrigerated cargo being transported around the world. While in 1980 33% of the refrigerated transport capacity in maritime shipping was containerized, this share rapidly climbed to 47% in 1990, 68% in 2000 and 90% in 2010. About 1.69 million TEUs of reefers were being used by 2009. All reefers are painted white to increase the albedo (share of the incident light being reflected; high albedo implies less solar energy absorbed by the surface) with the dominant size being 40 high-cube footers (45R1 being the size and type code). For instance a low albedo container can have its internal temperature increase to 50 °C when the external temperature reaches 25 °C on a sunny day while a high albedo container see its internal temperature increase to only 38 °C under the same conditions.
The refrigeration unit of a reefer requires an electric power source during transportation and at a container yard. Regular containerships have 10 to 20% of their slots adapted to carry reefers, with some ships having up to 25% of their slots being dedicated. It is important to underline that the refrigeration units are designed to maintain the temperature within a prefixed range, not to cool it down. This implies that the shipment must be brought to the required temperature before being loaded into a reefer, which requires specialized warehousing and loading / unloading facilities. A new generation of reefers is coming online, which are equipped with an array of sensors monitoring effectively the temperature and shutting the cooling plant when unnecessary. This enables to improve the reliability of temperature control and well as extend the autonomy of the reefer.
The growth of the intermodal transportation of reefers has increasingly required transport terminals, namely ports, to dedicate a part of their storage yards to reefers. This accounts between 1% to 5% of the total terminal capacity, but can be higher for transshipment hubs. The stacking requirements simply involve having an adjacent power outlet, but the task is more labor intensive as each container must be plugged and unplugged manually and the temperature to be monitored regularly as it is the responsibility of the terminal operator to insure that the reefers keep their temperature within preset ranges. This may also forbid the usage of an overhead gantry crane implying that the reefer stacking area can be serviced by different equipment. Even if reefers involve higher terminal costs, they are very profitable due to the high value commodities they transport.
4. The Setting and Organization of Cold Chains
Moving a shipment across the supply chain without suffering any setbacks or temperature anomalies requires the establishment of a comprehensive logistical process the maintain the shipment integrity. This process concerns several phases ranging from the preparation of the shipments to final verification of the integrity of the shipment at the delivery point:
Shipment preparation. When a temperature sensitive product is being moved, it is vital to first assess its characteristics. A key issue concerns the temperature conditioning of the shipment, which should be already at the desired temperature. Cold chain devices are commonly designed to keep a temperature constant, but not to bring a shipment to this temperature, so they would be unable to perform adequately if a shipment is not prepared and conditioned. Other concerns include the destination of the shipment and the weather conditions for those regions, such as if the shipment will be exposed to extreme cold or heat along the transport route.
Modal choice. Several key factors play into how the shipment will be moved. Distance between the origin and the final destination (which often includes a set of intermediary locations), the size and weight of the shipment, the required exterior temperature environment and any time restrictions of the product all effect the available transportation options. Short distances can be handled with a van or truck, while a longer trip may require an airplane or a container ship.
Custom procedures. If the freight crosses boundaries, custom procedures can become very important, since cold chain products tend to be time sensitive and more subject to inspection than regular freight (e.g. pharmaceuticals and biological samples). The difficulty of this task differs depending on the nation (or economic bloc) and the gateway since there are variations in procedures and delays.
The "Last Mile". The last stage is the actual delivery of the shipment to its destination, which in logistics is often known as the “last mile”. Key considerations when arranging a final delivery concern not only the destination, but the timing. Trucks and vans, the primary modes of transportation for this stage, must meet the specifications necessary to transfer the cold chain shipment. Also important is the final transfer of the shipment into the storage facilities as there is potential for a breach of integrity.
Integrity and quality assurance. After the shipment has been delivered, any temperature recording devices or known temperature anomalies must be recorded and made known. This is the step of the logistical process that creates trust and accountability, particularly if liability for a damaged shipment is incurred. If problems or anomalies that compromise a shipment do occur, an effort must be made to identify the source and find corrective actions.
Therefore, the setting and operation of cold chains is dependent on the concerned supply chains since each cargo unit to be carried has different requirements in terms of demand, load integrity and transport integrity.
5. Food Transportation
There is a variety of methods for the transport of food products with the banana accounting for the world's most significant commodity transported in the food cold chain with 20% of all seaborne reefers trade. Land, sea and air modes all have different structures for keeping food fresh throughout the transport chain. Innovations in packaging, fruit and vegetable coatings, bioengineering (controlled ripening), and other techniques reducing the deterioration of food products have helped shippers extend the reach of perishable products. For food products such as fruits and vegetables, time has a direct impact on their shelf life and therefore on the potential revenue a consignment may generate. Concomitantly, new transport technologies have permitted the shipment of perishable products over longer distances. For instance, improved roads and intermodal connections along the African coast reduced transport time for food to European markets from 10 days to 4 days.
Certain domestic or transnational supply chains may only require one transportation mode, but many times ground shipments are one link in a combination of transport modes. This makes intermodal transfer critical for the cold chain. Intermodal shipments typically use either 20 or 40 footers refrigerated containers that are capable of holding up to 26 tons of food. The container makes loading and unloading periods shorter and less susceptible to experiencing damage. The environments in these containers are currently controlled electronically by either plugging into a generator or power source on the ship or truck, but early food shipments would cycle air from stores of wet or dry ice to keep the food refrigerated. The efficiency of cold chain logistics permitted the consolidation of cold storage facilities.
Moving away from ice refrigeration has allowed for much greater distances to be traveled and has greatly increased the size of the global food market, enabling many developing countries to capture new opportunities. Another efficient mode for transporting foodstuffs is air travel. While this is a preferred form of travel for highly perishable and valuable goods due to its ability to move much faster over longer distances, it does lack the environment control and transfer ease of the ground and sea transports. Also, during the flight the cargo is stored in a 15°C – 20°C environment, but close to 80% of the time the package is exposed to exterior weather while waiting to be loaded onto the plane or being moved to and from the airfield. This is troubling considering the value of the food and the importance placed behind quality and freshness. In order for this form of food transport to experience growth among market users, more uncompromising strategies and regulations will have to be embraced and enacted.
Food transportation is an industry that has fully adapted to the cold chain and can, despite the problems with air transport, be considered the most resilient, particularly since a large majority of food products have a better tolerance to temporary variations of transport temperatures. As a result, small errors can be compounded without the concern of irreversible damage. For instance, for the transportation of produces, for every hour of delay in the pre-cooling of shipments, an equivalent one day loss of shelf life must be accounted. The usage of refrigerated containers has particularly helped, since they account for more than 50% of all the refrigerated cargo transported in the world. Source loading can be an important factor extending the shelf life of a cold chain product since it is loaded in a reefer directly at the place of production without additional handling. For instance, source loading into a reefer can expand the shelf life of chilled meat by about 25 days (from 30-35 days to 55-60 days) from conventional methods and thus considerably expand the market potential of the product.
The efficiency and reliability of temperature controlled transportation has reached a point which allows the food industry to take advantage of global seasonable variations, meaning that during the winter the southern hemisphere can export perishable goods to the northern hemisphere while an opposite trade, generally of smaller scale, takes place during the summer. Countries such as Chile have substantially benefited from this and have developed an active agricultural and food transformation industry mainly servicing the North American market during the winter, but also with several niche markets such as wine. A similar issue concerns some African countries such as Kenya that have developed a fresh produce and flower industries catering the European market. The fast food industry is also an active user of cold chain logistics as every outlet can be considered as a factory, with dozens of workers with schedules and shifts, inventory management and the supply chain of components (many of which are temperature sensitive), and which are assembly lines producing quality-controlled and high-volume products.
 
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