Design of shell and tube heat exchanger for ballast water treatment applications on ships based on simulation

Now, environmental issues are the mostly discussed issue and become a top priority in the world. Whether it’s environmental damage or environmental pollution. The issue of pollution and damage to the environment and ecology in the region, which have an impact on living organisms, both humans, animals and plants. Environmental damage and pollution can occur on land, water, and air. With various forms of damage and pollution, the methods of handling are different. This research will focus on damage and pollution in waters as well as methods of handling and prevention, especially in marine waters. This research focuses on designing a heat exchanger by varying its types, namely shell and tube heat exchanger. From the modification of model, it will be known which one is more effective in performance. Both temperature exchange, pressure drop, flow rates, dimensions and materials are simulated by software. Where these parameters are influenced by the characteristics of the ship’s power of main engine. From 2 model of shell and tube heat exchanger that are one pass-shell and two pass-shell the result for case 1 the effectiveness are 92% & 93%, case 2 are 93% & 94% and case 3 are 94% & 95%.


Introduction
Environment issues are mostly discussed issue and a top priority in many countries. The issue of pollution and damage to the environment and ecology in the region, which have an impact on living organisms. Ballast water in the world have become a major cause an ecological imbalance. The International Maritime Organization (IMO) has been actively taking regulated steps to minimize species moved, by adopting the International Convention for Ballast Water Management and Sediments Control in 2004.

Water Ballast Treatment
In research on ballast water treatment using heat, or thermal treatment, several have been done. As has been done by R. Balaji and O. Yaakob in 2011 with a case study research on the application of Ballast Water Treatment on MT vessels. Bunga Kasturi with engine power of 25090 kW by utilizing heat from the main engine and from a generator with a power of 1020 kW x 3 sets. Resulting in research, the total heat recoverable is 16924.59 kW during sailing. Total heat available 43844.39 kW (unloading). Total heat available 7453.4 kW (loading). [1] The research was developed in 2014 by R. Balaji and O. Yaakob. One treatment method is heat, which sterilizes ballast water from marine species. Systems that utilize waste heat from ships will provide an economic solution for ballast water treatment. Based on the analysis of waste heat available on existing crude oil tankers, although heat availability is visible, complementary treatment methods are required for high volume treatment. So, combined filtering and heating systems can be combined. Seawater circulating as secondary coolant in the engine is filtered and heated by taking heat from the engine system, rejection steam and exhaust gases. The planned system is a combination of taking heat from multiple sources on board and filtering can be optimized. By considering the components in the IOP Publishing doi:10.1088/1757-899X/1052/1/012035 2 system, it can be ascertained that the specific processes associated with each of them (ie heat exchangers and filters) for species mortality / isolation can be carried out. [2] Then another research, namely the use and utilization of heat from machines to kill microorganisms based on tests and IMO requirements conducted by R. Balaji and O. Yaakob in 2015 resulted in an average heat recovery from exhaust gases, namely between 15% to 33% of the input energy. Tests on species showed > 95% will die (mortality) in the temperature range 55 C to 75 C. [3] R. Balaji and O. Yaakob then began to conduct research on the design of a heat exchanger to be more optimal in the ballast water heating process in 2017. Optimization of the heating design, using engine exhaust gas as a uid fluid, and ballast water as a uid process, was achieved by using the Lagrangian method, the annual cost is an objective function. Limiting the number of variables, the optimal value is calculated by considering the cost for the utility fluid. In total, four optimal designs and three comparative designs were developed. Heat balance data of the tanker, specific fuel consumption values and fuel costs are considered design variables. Designs are compared based on annual costs, optimal exit temperature and optimal mass from the side of the heat exchanger. The heater design for ballast water treatment uses flue gas for the purpose of retrieving waste heat for ballast water treatment, scope for further improvement includes shell and tube side uids and tubular finned heat exchanger design. The availability and flow limitations of heat depend on the type of vessel, and designs can be worked on for other types of vessels. The increased realization of waste heat will provide a competitive advantage for heat treatment methods, not only in cost but also in increasing the treatment potential of the system. [4] Research was continued in 2017 by R. Balaji and O. Yaakob regarding the use of heat for ballast water treatment, namely the utilization of waste heat from ship engines as a potential source for heating ballast water. Similar to the schematic arrangement of a ship, a laboratory-scale heat exchanger collects waste heat from jacket water and exhaust gases to test mortality rates for marine species. The result is that mortality is in the range of 80-95% for phytoplankton, zooplankton and bacteria, which can be achieved by maintaining a temperature of 60-65 C for 60 seconds. In addition, the effect of centrifugal pump impellers can also increase the mortality of some species. [5] After that in 2018 by R. Balaji and O. Yaakob regarding the economic level of heat utilization from the main engine, the utilization of waste heat from ship engines could be a potential source for heating ballast water. Similar to the schematic arrangement of a ship, a laboratory scale heat-engine exchanger that collects waste heat from jacket water and exhaust gases to test species mortality rates. Heat treatment is proven to increase mortality in microorganisms and is more economical because it can save costs. [6]

Microorganism on Water Ballast
In the 1897, biologists had shown that marine plankton (deep-drifting organisms, most of which are microscopic) could pass through pumps into ships' seawater systems and survive. In 1908 it was reported that in Asia in the North Sea and northern Europe there was an invasion by Chinese mitten crabs believed to be the result of discharging ballast water. It wasn't until the 1970s that scientists began directly sampling the organisms in the ballast water. Many studies have shown that ballast tanks usually contain many species of animals, plants, protozoa, bacteria and viruses, even in quite large numbers. [7] Small planktonic organisms can be easily pumped in and out of the ballast tank. Plankton can be characterized as holoplankton, meroplankton or tychoplankton. Holoplankton spend their entire life floating in water, and include a variety of bacteria, protozoa, unicellular plants (phytoplankton), and small animals (zooplankton). The latter mainly consist of copepods, mysid shrimp, arrowworms and comb jellies in brine, water fleas and rotifers in freshwater. Meroplankton spend part of their life cycle drifting away in plankton, and include the larvae or eggs of various worms, shellfish, snails, crabs, starfish, fish, and other organisms. Tychoplankton are organisms that usually live on the bottom. Certain other organisms which in the narrow sense are not planktonic can be associated with planktonic hosts, such as certain viruses and nematodes, parasites and flatworms. In addition, some organisms that are non-planktonic in nature can be brought into a ballast tank attached or attached to

Ballast Water Treatment Method
From year to year, ballast water treatment technology has developed and many kinds. Related companies have even carried out mass production to meet market needs. In this research, ballast water treatment will be carried out using heat, so that it is included in the mechanical method category.

Literature review and collecting data
Problem identification is carried out based on problems that occur in the field, in this case, the problem of pollution due to ballast water. Then from this problem then conduct a literature study and data collection. With the aim of obtaining basic knowledge and data from previous studies that can be used as a reference for further research. At this stage, a study of references contained in papers, journals, proceding, conferences and supporting books is carried out. The collection of various kinds of references serves to strengthen the theoretical basis of thermal ballast water treatment.

Heat exchanger modeling
The next step after conducting a literature study and gap analysis is to model the heat exchanger with the collected data. Data related to ship engine power and ship speed, this data is used for the input of heat exchanger modeling, so that it will be seen which heat exchanger has the best performance.

Heat exchanger simulation
After the calculation and modeling process has been carried out, a simulation can be performed.
Simulations are carried out based on the data obtained and mathematical calculations.

Data analysis
The final step is to analyze the result data from heat exchanger modeling. The variable of concern is the performance of the heat exchanger based on thermal efficiency and pressure drop.

Results and Discussion
Before doing modeling, there are several things that need to be done first, namely the simulation design. In this case there are 2 calculations, that are for one pass-shell and two pass-shell. Calculation for energy conservation and heat transfer rate equation: The total of heat transfer rate from hot to cold fluid is: Whereas the following is a formula for finding the Log mean temperature difference: Based on calculation and simulation can be the following results were obtained.

Conclusion
Based on calculation and simulation, can be take conclusion that: One pass-shell With an engine power of around 1000 kW, to get effectiveness 92%, the dimensions of the length of the heat exchanger are 4 meters with 150 tubes. With an engine power of around 2000 kW, to get an effectiveness 93%, the dimensions of the length of the heat exchanger are 5 meters with 150 tubes. With an engine power of around 3000 kW, to get effectiveness 94%, the dimensions of the length of the heat exchanger are 6 meters with 150 tubes. Two pass-shell With an engine power of around 1000 kW, to get effectiveness 93%, the dimensions of the length of the heat exchanger are 4 meters with 150 tubes. With an engine power of around 2000 kW, to get an effectiveness 94%, the dimensions of the length of the heat exchanger are 5 meters with 150 tubes. With an engine power of around 3000 kW, to get effectiveness 95%, the dimensions of the length of the heat exchanger are 6 meters with 150 tubes.