The Economic Thickness of Insulation for Steam Process Distribution Pipelines

Steam pipes are very important in engineering application and are widely used. Thermal insulation is one of the most effective energy-conservation measures in hot pipes. One of the primary purposes of insulation is to conserve energy and increase plant profitability by reducing operating expenses.  In existing plants, the planned and conscientious maintenance of insulated hot pipes is required to minimize financial and thermal losses. This seems like a statement of the obvious, and it is. Although an increase in the amount of insulation applied will raise the initial installed cost, but it will reduce the rate of heat loss through the insulation. This paper aims to confirm whether there is an optimal insulation thickness appropriate to the minimum total cost, and to see what the values and facts affecting the value of the minimum cost are. An optimization model is performed depending on Life Cycle Cost analysis. For this purpose, a computer program has been prepared based on the flow chart of the operation procedure overviewed in this paper. The results of Calculations carried out by the computer have given a new concept that is termed as “the critical thermal conductivity of insulation material”, the exceeding of which makes the insulation of pipe a factor that contributes to increase of total cost (ΣC) but not the opposite. The study carried out on steam pipe with outside diameter of 0.1m, steam temperature of 120 °C, steam price of 0.005 $/kg and insulation material price of 175$/m3 shows that the critical thermal conductivity of insulation material is 0.21 w/(m. °C), the  exceeding of which will not cause  decrease in the expected total cost of steam pipe insulation and the   optimal insulation thickness  can not be achieved. When the thermal conductivity of the insulation material used is less than that of the critical thermal conductivity by 0.10 w/(m.°C), the total cost drops from 9.69 $/(m.year) without insulation to minimum total cost of  5.184$/(m.year)  with the thermal insulation thickness  of 0.092m. The outside temperature of insulation material drops from 117 to 34.4 °C. The effect of the price of steam generation, the price of insulation material, pipe diameter and temperature of steam on the optimal insulation thickness and critical thermal conductivity of insulation material are overviewed in this paper. Keywords: Optimum insulation thickness, steam pipe insulation, thermal conductivit

Reducing the Cost of Pumping High Viscosity Fluids for Jordanian Industry

All industrial facilities have a network of piping that carries liquids. The frictional power required is dependent on rate of flow, pipe size (Diameter), overall length of pipe, pipe characteristics (surface roughness, material, etc.) and properties of the liquid being pumped. Heating high viscosity liquids leads to drop in their viscosity. As a result,    pressure loss resulting from friction deceases, and these pressure losses result in low cost of pumping. But nevertheless, the heating operation demands additional cost that increases progressively with the increase of    heating temperature degree. This paper aims to find out the effect of heating temperature degree on cost of pumping and heating, and eventually on the total cost (heating plus pumping). In addition, the paper aims to confirm whether there is an optimal heating degree topt appropriate to the minimum total cost ?Cmin, and to see what the values and facts affecting the value of the minimum cost are. For this purpose, a commuter program has been prepared based on the flow chart of the operation procedure overviewed in this paper. Calculations carried out by the computer show the effect of price change of electrical energy $/(kW.h) on the optimal heating temperature degree, and the  effect of the price of steam generation  demanded   for the heating operation,$/kg on the optimal heating temperature degree as well , in addition to the effect   of flow rate change of  the liquid which will be pumped, kg/s. The results also show that the heating optimal degree occurs at the transitional moment from laminar to turbulent flow. When checking the effect of diameters of the used pipe on the optimal heating degree, the results have given a new concept that is termed as “the critical diameter”, the exceeding of which makes the heating operation a factor that contributes to increase of total cost, ?C but not the opposite. The optimal heating degree appropriate to the minimum total cost (heating plus pumping) only occurs when diameters of the pipes used are less than that of the critical diameter. The study carried out  on sugar syrup shows that the critical diameter of pipes is dcr=0.046 m, the  exceeding of which will not cause  decrease in the expected total cost of   the heating operation , and the   optimal heating degree  can not be achieved. When the diameter of the pipes used is  less than that of the critical diameter by 15mm, the total cost drops 1.5 $/hour with the heating temperature degree  increases from 20-29°C when the   liquid flow rate is   6 kg/sec ,  the electrical energy price is  0.081$/kW/h , and the demanded steam price is 0.0055 $/kg. The effect of the liquid flow, electrical energy price, and diameters of the pipes used on the  optimal heating degree and the critical diameter  are overviewed in this paper

Selection of Thermal Insulation Thickness of Cold Store Enclosures

This paper aims to set  a mechanism   in order to calculate the  economical  thickness of  thermal insulation layer of  external walls of cold storage plant  based on a comprehensive  techno-economic analysis  of  thermal insulation cost, in addition to the cost related to the production of necessary refrigeration  to compensate for heat flow through the exterior walls into the cold storage and conservation plant. Some research  that dealt with this topic provided techno-economic analysis for the  cost of thermal insulation and the  production of refrigeration based on  exterior  walls area of the cold storage plant,  which  does not  make  sense,  and that it  is difficult to determine the effect of the operational expenses. Therefore, the present study stems from the idea that the cold storage and conservation plant is dedicated to prolong the period of food conservation, so the course of techno- economic analysis has been shifted to take into account one ton of  food stuff  stored in cold storage and conservation plant  to be refrigerated and conserved  instead of considering the   external walls area. In addition, this paper provides a more accurate formula to calculate the specific cost of refrigeration equipment bx in order   to skip the percentage of mistake used to occur in calculating the overall standard heat transfer coefficient of external walls caused by applying the weighted average value of the specific cost of refrigeration equipment bxa. The obtained results resulting from the   use of a   computer-programmed method in   techno-economic analysis of the cost   enhanced the fact that the impact of cold storage plant capacity and specific cost of refrigeration equipment on the economical thickness of the insulation layer is correct. This  justifies  the concept   proposed  in this paper that associates  the  techno- economic analysis of costs to be  the capacity of the cold storage plant  instead of the   exterior walls area unit, where obvious decease  in the values ??of the operational  cost Oc , Od and the minimum cost ( Pmin ) with the   increase cold storage  and conservation plant   capacity. The results also show  that economically optimal thermal resistance (  Ro.ec )  of  heat  transfer through the exterior walls and the economic thickness of insulation layer  have been effected by  the specific cost of refrigeration equipment . It has been noticed that bx decreases from 0.94- 0.54 with increase of the cold storage plant capacity from 400 to 5000 ton. This leads to 6% decrease in economically optimal thermal resistance and the economical thickness of the insulation layer. Keywords: thermal insulation, economical  thickness, techno-economic analysi

Textural Quality and the loss in Nutrients of Potatoes and Carrots Affected by Blanching and Storage Conditions

As potatoes and carrots are important horticultural products and an important raw material for the food processing industry, so inevitably it is stored in fridges in order to be available all year long. Texture is a critical quality factor for vegetables. Successful production of acceptable products requires serious attention to textural changes and attaining of this aim involves a good knowledge of the factors that influence texture. Both the textural and the loss in nutrients of processed vegetables are influenced not only by variety and maturity at harvest, but by processing and storage conditions as well. Blanching combined with cold storage is an excellent preservation method to extend vegetables shelf-life. While many of the researchers in this area investigated the properties of those of thermally processed (sterilized, dehydrated, frozen) products, little attention has been given to the interactive nature of the stages in the various processing operations or to variations within a particular stage. The objective of this study was to investigate the effects of different blanching and storage conditions on textural and loss in nutrients of potatoes and carrots. Before Potatoes and carrots were frozen using plate and air blast, the samples were blanched using water and steam blanching with time variations within each method. The physical properties of interest were hardness, cohesiveness, and loss of sugar. The loss in sugar determined and the texture changes in the products during processing are illustrated. Keywords: loss in nutrients of potatoes, blanching, storage condition