Waste Heat Recovery from Exhaust Gas and Cooling Water as Water Heater on Domestic System of a Cruise Ship 48 meters

Cruise ship is a ship used for recreational and entertainment purposes. As a means of vacation and entertainment, the design of this transportation equipment requires more attention. The design of the ship itself must be able to make it comfortable for the passengers. One way to increase comfort for cruise ship passengers is by adding heating water to the domestic system. Will need a large amount of electrical energy if you use an electric heater. While in the engine room there is exhaust heat that can be utilized. The purpose of this final project is to plan the utilization of waste heat contained in the exhaust gas and cooling water system (high temperature) as a water heater on the domestic system. The method used is analysis of calculations and references from other sources. From the results of the calculation analysis it was found that the hot water requirements of this vessel were 3409 liters/day and needed a heat 167.12 kJ/s to increase the water temperature from 25 0 C to 66 0 C. From the calculation results, the 50% load engine has a heat 469 kJ/s, 75% load engine has a heat 645 kJ/s, 80% load engine has a heat 729 kJ/s, 100% load engine has a heat 781 kJ/s, while in cooling water system (high temperature) has a heat 252 kJ/s. Tank insulation using glasswool with thickness 610 mm. While the insulation on the pipe uses glasswool with thickness 50 mm. By replacing electric water heater by utilizing heeat waste can be minimize the cost up to Rp. 245,211.833 per day or Rp. 7,356,355.008 per month.


I. INTRODUCTION
The cruise ship is a ship that is used specifically for recreational and entertainment purposes. As a means of vacation and entertainment, the design of this transportation requires more attention. The design of the ship itself must be able to make it comfortable for the passengers. One of them, to increase comfort for cruise ship passengers is by adding heating water to the domestic system. In obtaining hot water on domestic systems on ships there are several ways by using electricity, gas, and solar power.
Electricity consumption for the operation of electric water heaters on ships requires a large amount of energy and costs are expensive. Whereas if using solar power the cost that must be spent is far more expensive than using an electric water heater.
While in the engine room there is wasted heat formed from the engine and other components. At present day there are many technologies that utilize waste heat energy to be used as the turbocharger, refrigeration, and desalination. So to obtain hot water without using electric water heater and solar power, it is a planned system that exploits waste heat for a domestic system in a ship. By utilizing this waste heat indirectly we can reduce the need for electricity usage [1][2][3][4].

A. Waste Heat
Waste heat recovery is one example of energy savings which aims to improve the efficiency of fuel use. In diesel engines, there are 3 main heat sources that can be utilized, including exhaust heat generated from jacket water, exhaust gas, and also from cooling water [1][2][3][4]. Factors affecting Waste Heat Recovery as follows: 1) Heat Quantity Heat quantity is the amount of heat energy contained in waste heat.

2) Waste Heat Temperature
Waste heat temperature is a factor that determines whether the temperature of the exhaust heat can be utilized.

3) Waste Stream Composition
Waste stream composition is a chemical content found in waste heat, which can affect the material and recovery process. 4) Minimum allowable temperature limit

B. Heat Transfer
Heat transfer is the process of transferring heat or heat caused by temperature differences. Where heat will move from high temperatures to lower temperatures. This transfer process will continue until there is a temperature balance in both media [5][6][7][8][9][10]. The process of heat transfer can be divided into three, namely as follows: 1) Conduction Conduction heat transfer is heat transfer that occurs on a solid medium, or on a silent fluid. Conduction occurs due to temperature differences between one surface and another on the media.

2) Convection
International Journal of Marine Engineering Innovation and Research, Vol. 3(3), Mar. 2019. 84-92 (pISSN: 2541-5972, eISSN: 2548-1479 85 Convection is the transfer of heat that occurs to a silent fluid to a fluid that flows, and vice versa which occurs due to differences in temperature.

3) Radiation
Radiation heat transfer can be said to be the process of transferring heat from one medium to another due to temperature differences without the need for intermediate media.

C. Heat Exchanger
The heat exchanger is a device used to exchange heat between two fluids, both of which have different temperatures. In general, heat exchangers used in various applications, for example, are used as heating and air conditioning systems in homes, used as chemical processes and as power plants [11].
Heat transfer in a heat exchanger usually involves two heat transfer processes, namely convection in each liquid and conduction through a wall separating two liquids [12]. The heat transfer rate between two fluids in a heat exchanger depends on the amount of temperature difference that varies along the heat exchanger. The types of heat exchangers vary greatly and can be classified as follows [13][14][15]:

1) Number of streams
Most processes of heat transfer between fluids involve only two different types of fluid. Such as water with water, steam with water, steam with sea water, and so forth 2) Transfer Process According to the transfer process, the heat exchanger is divided into two, namely direct contact and indirect contact. The definition of direct contact itself is the transfer of heat transferred between the cold fluid and hot fluid through direct contact, between these fluids there is no dividing wall. While the understanding of indirect contact heat transfer process between these two fluids is limited by a dividing wall. Hot fluids and cold fluids flow simultaneously while heat energy is transferred through the separation wall.

3) Construction geometry
The geometry of construction for the heat exchanger is divided into three types, namely tubular, plate, and extended surfaces.

4)
Heat transfer mechanism Basically, the heat transfer mechanism is used to transfer heat energy from the fluid that is on one side of the heat exchanger to the separation wall. There are several types of heat transfer mechanisms, namely: The next classification of heat exchangers is based on the area of the contact area between inter-fluid heat transfer. The parameters used in this classification are the large unit surface area of contact in each heat exchanger volume. The more surface area of the contact area of heat transfer per unit volume, the greater the heat transfer efficiency obtained. But this must also pay attention to the type of working fluid used. The greater the particle content in the fluid, the lower the need for the surface area of the heat transfer contact area in the heat exchanger.

D. Selection of Heat Exchanger
There are many criteria in choosing a heat exchanger, but the main criteria are the type of fluid that must be handled, operating pressure and temperature, heat energy, and cost. While the fluid involved in heat transfer can be categorized into temperature, pressure, phase, physical properties, toxicity, corrosivity, and fouling tendency. The operating conditions for heat exchangers vary in a very wide range, and a broad spectrum of requests is imposed for their design and performance. All of this must be considered when assessing the type of unit to be used. When choosing a heat exchanger the following points must be considered [14]. 

E. Calculation of Heat Exchanger
The research method is based on the following calculations [11,12]

F. Domestic System
Domestic system is a system that aims to serve the needs of fresh water and sea water for the passengers of the ship during the voyage. Domestic systems are used in some rooms for example:  Bathroom  Washing place  Kitchen In the domestic system is divided into 2 systems, namely the fresh water supply system, and seawater supply system, where the components of the system are as follows: 1. Sea chest is a place for the entry of seawater for the needs of a seawater supply system on board. 2. Seawater pump functions to move sea water from sea chest to hydrophore. 3. Seawater hydrophore is a place to store seawater before being distributed for domestic purposes on a ship. 4. Freshwater tanks are a place to store fresh water on a ship. 5. Freshwater pumps a tool used to move fresh water from the fresh water tank to hydrophore. 6. Freshwater hydrophore is a place to store fresh water before being distributed for domestic system needs.

A. Data collection
Data collection for this research is the main dimension, the specifications of the engine on the 48meter cruise ship, the need for fresh water for the domestic system on a 48-meter cruise ship.

C. Tank Insulation
In determining the thickness of the insulation the author uses the Jimmy Kumana and Samir Khotari methods in the Predict Storage Tank Precisely Heat Transfer paper. Table 5 until table 9 are calculation result in water tank and insulation.

IV. CONCLUSION
Based on the results of calculations from data analysis in utilizing waste heat like a heater (water heater) for domestic systems, it can be summarized as follows: 1) Fresh water needed for the supply of hot water in the domestic system is 3409 Kg/day and requires heat of 167.12 kJ / s to increase the temperature from 25 0 C to 66 0 C. 2) From the calculation results, the heat output from the exhaust gas is 469 kJ / s when the engine loads 50%, 645kJ / s when the engine loads 75%, 729 kJ / s when the engine loads 80% and 781 kJ / s from the 100% load engine. While the heat generated in cooling water (HT) is 252 kJ / s. 3) From the calculation results that have been planned, the heat exchanger used is shell and tube type with the following specifications Shell outer diameter 15.25 in, number of baffle 4, number of pass on shell side 1, while inner diameter on tube side 1 in, number of pass on tube side 2, distance between tubes 1.25in, length of tube 8 ft, number of tubes 68, and distance between baffles 3.05 in. 4) Tank insulation thickness of 0.2 ft or 610 mm using glass wool material, within 24 hours the temperature of fresh water drops to 63.16 0 C. While the insulation of the pipe is 50 mm with glass wool material, the temperature in 24 hours drops from 66 to 65.14 0 C. 5) By utilizing waste heat as a substitute for an electric water heater for domestic needs on a 48-meter cruise ship, it can minimize the expenditure of Rp.